Hi,
i integrated a relay bypass circuit in a pedal, i'm surprised by the power drained by this circuit (more than 53mA, only from this circuit, not the effect).
I knew that using NE555P will drain a lot of power, but i expected more in the 25-30mA range.
I'm using NA5WK takamisawa, fujitsu relay.
Does it ring a bell to someone?
Thank you!
(https://i.postimg.cc/YjNhWgxM/2022-04-05-21h54-19.jpg) (https://postimg.cc/YjNhWgxM)
I looked at the data sheet for the relay...is this a 5v or 9v relay? Isn't it not 'what you expect', but what the manufacturer lists for operating current of the relay? ( voltage/coil resistance)
Quick way to know is to measure the relay's current draw when you actuate it. If it's a 5v model running on 9v expect higher draw (and probably blue smoke)!
According to datasheet https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf (https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf), your relay coil is rated at 5V where you feed it with 9V (minus a BC549 VCEsat), hence it should draw much more than 28mA current by its own..
Adding 10 - 15mA for NE555 plus LED current (?) we come close to your measurement..
Either place a coil series resistor for 4V drop (according to coil nominal current - page 3), or use a NA9WK, or live with that current consumption and a very warm relay.. :icon_wink:
edit: Sir Mike is by far faster.. :icon_wink:
Quote from: antonis on April 05, 2022, 04:30:55 PM
According to datasheet https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf (https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf), your relay coil is rated at 5V where you feed it with 9V (minus a BC549 VCEsat), hence it should draw much more than 28mA current by its own..
Adding 10 - 15mA for NE555 plus LED current (?) we come close to your measurement..
Either place a coil series resistor for 4V drop (according to coil nominal current - page 3), or use a NA9WK, or live with that current consumption and a very warm relay.. :icon_wink:
edit: Sir Mike is by far faster.. :icon_wink:
Quote from: GibsonGM on April 05, 2022, 04:29:23 PM
I looked at the data sheet for the relay...is this a 5v or 9v relay? Isn't it not 'what you expect', but what the manufacturer lists for operating current of the relay? ( voltage/coil resistance)
Quick way to know is to measure the relay's current draw when you actuate it. If it's a 5v model running on 9v expect higher draw (and probably blue smoke)!
Thanks for your answers guys
i'm using NA5WK so it's the 5V version
(https://i.postimg.cc/Pps9LH0x/2022-04-06-01h25-43.jpg) (https://postimg.cc/Pps9LH0x)
Putting a 142ohm resistor in serie with the relay coil (178ohm) to get about 5V on the coil should shift down a bit the current drained and releive the coils pain?
As i can't find any 9v relays like the NA9WK (unavailable), best choice would be to use this serie resistor to prevent the 5V relay from burning?
Seeing the constuctor datasheet above, wouldn't it be perfect to use the 12V version (NA-12WK), which is available, has a 1K coil, and has a "must operate Voltage" of 9V? Or this "must operate voltage" being too close to the supply voltage may introduce some troubles?
Powering with 9V a 12V nominal voltage relay is like continously balancing on ineffectiveness cusp.. :icon_wink:
(https://i.imgur.com/6xvbtIt.png)
A rather long but usefull text about relays:
https://media.digikey.com/pdf/Other%20Related%20Documents/Panasonic%20Other%20Doc/Small%20Signal%20Relay%20Techincal%20Info.pdf (https://media.digikey.com/pdf/Other%20Related%20Documents/Panasonic%20Other%20Doc/Small%20Signal%20Relay%20Techincal%20Info.pdf)
I should use LED + CLR(properly sized) between relay coil and BJT Collector if I was sure about LED long life..
Try a standard value of 150 for the dropping resistor, that should work. If you had to you could go a bit lower using 2 R's in series; test its operation. I'd say if you HAVE the 5v relay, use it. If you BUY one, get the 9V version. There's nothing wrong with dropping the voltage.
Running the 12V on 9V does seem too close to the minimum value, and you may not really be just at 9V..what if you have 8.2V? (I'd test the operation w/dropping R down to at least 8V to be sure it works w/low battery).
Antonis is still awake where he is - I am just waking up this morning so I am slower :icon_mrgreen:
When you run a 5V coil from 9V using a series resistor you want to match the *current* for the relay 5V spec.
If you then compare that current to the 9V coil current you will see the 5V coil + resistor requires a lot more current.
A 9V coil gets its resistance from more turns of thinner wire on the coil. The turns contribute to the pull so you need less current. In the 5V + resistor case the resistance lowers the current but it does not contribute more turns to the coil.
For ultimate low power look up latching relays. The don't use any power once they are switched to a particular state. The way you drive these relays is different.
thanks you for your answers again.
I get that the resistor in serie could cause more problem, and that the best thing is to have a real 9V relay.
The NA9WK i would need, is discontinued, and really not findable where i live (in europe), or at a decent price (i just can't pay more than 10$ for a relay...)
I have tested/breadboarded with a RY9WK i found, which have a different footprint, different pinout and is bigger. I have to do a new pcb to fit it in.
RY9WK datasheet : https://www.datasheet-pdf.info/attach/1/3098632639.pdf
NA9WK datasheet : https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf
It's working good, with a maximum current drained of 30mA, which is perfect to me.
Nasty popping is just bothering me....
nb : I found this very useful for Transistor Relay driver, full of useful datas : https://www.homemade-circuits.com/how-to-make-relay-driver-stage-in/
Quote from: jackwithoneye on April 06, 2022, 12:33:45 PM
Nasty popping is just bothering me....
If you post a schematic of circuit of interest (effect On/Bypassed) we might find a remedy.. :icon_wink:
Yes, please post the full schematic.
FYI. There is no problem with a dropping resistor; it is operating at 5V 'at the top of the relay', but since you found a 9V that will make is easier for you!
here we go!
Actually, the pop is not "That bad", it happens especially when the FX output volume is high.
It's a tone bender inspired fuzz with npn transistors.
Note that there is no pulldown resistors on the FX schematic, but there's one next to the JACK OUT switch of the relay (R7).
the FX part :
(https://i.postimg.cc/mhpQvbdc/fuzz.png) (https://postimg.cc/mhpQvbdc)
the relay bypass part (with the old relay before last day 9v relay):
(https://i.postimg.cc/5jrCPs0L/2022-04-05-21h54-19.jpg) (https://postimg.cc/5jrCPs0L)
Although 100nF shouldn't pop heavily, place a 1M resistor between R8/C3 and GND.. :icon_wink:
Quote from: antonis on April 06, 2022, 05:06:12 PM
Although 100nF shouldn't pop heavily, place a 1M resistor between R8/C3 and GND.. :icon_wink:
I tried but it doesnt reduce the pop, which is not a bassy pop, more of a "trebly clicky pop" (it's not the click from the relay ;D ;D) it's coming out from the speaker :icon_biggrin:
Does popping occur both for ON and OFF switching..??
Quote from: antonis on April 06, 2022, 05:52:14 PM
Does popping occur both for ON and OFF switching..??
yes
Quoteyes
The effects circuit (not shown) should have a resistor to ground on the FXOUT line, say 100k; you might already have this. R7 is probably not required (and is perhaps undesirable as it loads the input in bypass mode). As a precaution, you could optionally add a 1M to 2M2 from FXIN to ground.
It could be the switching circuit itself. Perhaps even caused by the relay current changing. Add a 100uF cap from +9V_PAD to ground. If you have a resistors in series with the supply rail for filtering the switching circuit (+relays) should be powered before the filtering resistors.
Make sure you have diodes across the relay coils, like in the link you gave.
i posted the effects circuit few posts above, here it is :
the FX circuit :
(https://i.postimg.cc/mhpQvbdc/fuzz.png) (https://postimg.cc/mhpQvbdc)
the relay bypass part (updated with the 9v relay, R7 became R3):
(https://i.postimg.cc/w3mVS9TT/2022-04-07-00h52-07.jpg) (https://postimg.cc/w3mVS9TT)
Quote from: Rob Strand on April 06, 2022, 06:22:58 PM
Quoteyes
The effects circuit (not shown) should have a resistor to ground on the FXOUT line, say 100k; you might already have this. R7 is probably not required (and is perhaps undesirable as it loads the input in bypass mode). As a precaution, you could optionally add a 1M to 2M2 from FXIN to ground.
It could be the switching circuit itself. Perhaps even caused by the relay current changing. Add a 100uF cap from +9V_PAD to ground. If you have a resistors in series with the supply rail for filtering the switching circuit (+relays) should be powered before the filtering resistors.
Make sure you have diodes across the relay coils, like in the link you gave.
-ok i'll try to move the pulldown resistor R3 (ex-R7) to the FXIN instead of on JOUT.
- the 100uF after the protection diode on the power supply part of the FX circuit is not enough? Should i add the small resistor you're talking about and put this 100uF cap before?
-The diode D1 is in place over the coil.
Quotei posted the effects circuit few posts above, here it is :
Sorry, I somehow missed that. It changes what I said a bit.
Quotethe relay bypass part (updated with the 9v relay, R7 became R3):
OK probably don' t need that resistor.
Also, for the FXOUT output. No need for a resistor to ground as the existing output pot on the effect already does the same thing.
Optional 1M to 2M2 resistor on the input worth a long shot (it won't hurt).
Quote-The diode D1 is in place over the coil.
OK looks good.
Quote- the 100uF after the protection diode on the power supply part of the FX circuit is not enough? Should i add the small resistor you're talking about and put this 100uF cap before?
Well these types of circuits can be very sensitive to noise on the supply.
You might try:
+9V ---diode ---- 100uF to ground [this rail to switching ckt pwr] ---> 100R ---> 100uF to ground [this rail to effect power]
If you hear some improvement then the power is likely to be the cause.
Quote from: Rob Strand on April 06, 2022, 07:12:02 PM
Quotei posted the effects circuit few posts above, here it is :
Sorry, I somehow missed that. It changes what I said a bit.
Quotethe relay bypass part (updated with the 9v relay, R7 became R3):
OK probably don' t need that resistor.
Also, for the FXOUT output. No need for a resistor to ground as the existing output pot on the effect already does the same thing.
Optional 1M to 2M2 resistor on the input worth a long shot (it won't hurt).
OK, this 1M/2M2 has to be directly to the JIN, right? not on the input of the FX circuit post-relay (that i tried, no improvement)?
Does it make a difference if i just solder a 1M/2M2 between Tip and sleeve on the Input jack connector, or it has to be as close as possible to relay on pcb?
And do you think this 1M/2M2 on the input would change the impedance or interfere with the response with the guitar volume pot, considering a fuzz pedal is -sensitive/reactive- for cleaning-up with the guitar volume pot, like a fuzz face?
Quote
Quote-The diode D1 is in place over the coil.
OK looks good.
Quote- the 100uF after the protection diode on the power supply part of the FX circuit is not enough? Should i add the small resistor you're talking about and put this 100uF cap before?
Well these types of circuits can be very sensitive to noise on the supply.
You might try:
+9V ---diode ---- 100uF to ground [this rail to switching ckt pwr] ---> 100R ---> 100uF to ground [this rail to effect power]
If you hear some improvement then the power is likely to be the cause.
Thank you a lot!!! i'll try this tomorrow (it's very late in my timezone :icon_wink:) and will tell you if it improves
Edit : i changed the transistor base resistance (R2) from 3K to 220K to match the optimal coil current (17mA at 9V) considering the Q1 HFE (550) like explained in the earlier posted link ( https://www.homemade-circuits.com/how-to-make-relay-driver-stage-in/ )
Quote
OK, this 1M/2M2 has to be directly to the JIN, right? not on the input of the FX circuit post-relay (that i tried, no improvement)?
Does it make a difference if i just solder a 1M/2M2 between Tip and sleeve on the Input jack connector, or it has to be as close as possible to relay on pcb?
And do you think this 1M/2M2 on the input would change the impedance or interfere with the response with the guitar volume pot, considering a fuzz pedal is -sensitive/reactive- for cleaning-up with the guitar volume pot, like a fuzz face?
Well, there's no real reason to have the grounded resistors on the either jacks themselves. The main reason is it loads the input unnecessarily when in bypass - kind of undermining the idea of true-bypass.
Nonetheless there's nothing stopping you doing the experiment to track down very obscure problems. In which case it doesn't matter which end of the wire you place it.
If you are going to add a resistor to the input then FXIN is the correct place to put it. Under normal circumstances shorting the input in bypass mode, like your circuit does, makes the FXIN resistor to ground redundant. If you find no improvement then that's fine. It just means it's working normally without any weird stuff happening.
FYI you can see the added input resistor on this schematic,
http://www.generalguitargadgets.com/pdf/ggg_bmp_tri_sc.pdf
Quote
Thank you a lot!!! i'll try this tomorrow (it's very late in my timezone :icon_wink:) and will tell you if it improves
On paper the noise through the supply theory is high on the list. It's very much worth trying. If it gives an improvement but does not completely remove the click that could just mean we need to do more work in that area. It can also mean there's two problems and the extra caps only got rid of one cause.
Over the years on the forum there have been a few instances where relay circuits clicked as if the switching noise on the coil was getting through to the contacts.
QuoteEdit : i changed the transistor base resistance (R2) from 3K to 220K to match the optimal coil current (17mA at 9V) considering the Q1 HFE (550) like explained in the earlier posted link ( https://www.homemade-circuits.com/how-to-make-relay-driver-stage-in/ )
That value is not really "optimal" as such. It's more a "minimal" base current / "maximum" base resistor case. What is much more common for transistor switching circuits is to use a base resistor 5 to 10 times smaller than that maximum value. So in your case that would be 220k/10 = 22k to 220k/5 = 47k. The 3k on the original is probably OK and lets you use lower gain transistors but it's probably going a bit overboard. It's not an area that needs a precise value. You might only split hairs if the circuit driving the transistor has limited output current.
As Rob said above, you use BC549 as a "switch" (Saturated - Cut-off) so you only need plenty of Base current (ON) and lack of it (OFF).
The later is easily obtainable but the former needs a conservative design (involving hFE worst case scenario, coil intial current, LED current and lowest "wasted" current..)
All the above result into an appreciably undersized Base resistor..
P.S.
Is there any possibility to feed relay switcing configuration from an independent source (like another PS or battery..), to see if click/pop persists..??
A couple of thoughts:
1. The NE555 itself is known for its current spikes when switching between high and low states. You might need more bypassing right at the IC to limit the noise from the current spike. There is a CMOS version of this device that could drive a Darlington transistor or small power MOSFET to reduce the required output current.
2. The noise from the coil itself is due to the rate at which the current rises and falls. A capacitor to ground at the switching transistor base may reduce the inductive kick when the coil turns off and the current ramp when the coil turns on. Splitting the base resistor into two equal series resistors and placing the cap to ground from their junction may let you get away with a smaller capacitor.
Quote from: amptramp on April 07, 2022, 08:11:30 AM
A capacitor to ground at the switching transistor base may reduce the inductive kick when the coil turns off and the current ramp when the coil turns on. Splitting the base resistor into two equal series resistors and placing the cap to ground from their junction may let you get away with a smaller capacitor.
+1 :icon_wink:
Thanks for all your feedbacks!
here are the results :
-Putting a 1M Resistor to ground on the FXIN doesn't change anything (for the popping)
- I had adjusted the R2 (transistor driver resistor to a lower value 10K)
- i tried to use 2 differents (basics) power supply to feed the FX circuit and the relay bypass circuit. Still popping at high level of output volume setting on the FX (but only during silence or low level playing, maybe the pop is hidden/masked when i play louder, but i don't hear it)
Quote from: amptramp on April 07, 2022, 08:11:30 AM
A couple of thoughts:
1. The NE555 itself is known for its current spikes when switching between high and low states. You might need more bypassing right at the IC to limit the noise from the current spike. There is a CMOS version of this device that could drive a Darlington transistor or small power MOSFET to reduce the required output current.
2. The noise from the coil itself is due to the rate at which the current rises and falls. A capacitor to ground at the switching transistor base may reduce the inductive kick when the coil turns off and the current ramp when the coil turns on. Splitting the base resistor into two equal series resistors and placing the cap to ground from their junction may let you get away with a smaller capacitor.
1/ you mean the ICM7555, LMC555 or TLC555 i think, interesting, too bad i have 25x NE555, i should order few ICM7555 to try
2/ what kind of cap are you thinking of? I tried with a 100nF film, that does not affect the popping thing
Try to wrap relay in grounded aluminum foil.. :icon_wink:
(99% it shouldn't work but we aim to 1%..)
Quote from: antonis on April 07, 2022, 03:35:43 PM
Try to wrap relay in grounded aluminum foil.. :icon_wink:
(99% it shouldn't work but we aim to 1%..)
:icon_lol: :icon_lol: :icon_lol:
if i wrap myself in aluminium, it helps?
A Faraday cage should be more economical.. :icon_wink:
Quotei tried to use 2 differents (basics) power supply to feed the FX circuit and the relay bypass circuit. Still popping at high level of output volume setting on the FX (but only during silence or low level playing, maybe the pop is hidden/masked when i play louder, but i don't hear it)
So are you basically saying it is better than before?
Also, is the click still happening on both changes in state ie. effect off to on and effect on to off.
If so then the supply filtering might be on the right track.
Ideally the switching circuit (the whole thing) should have its own ground which is run back to the supply input. Lookup star grounding. Its possible to get glitches on the grounds. I only 50%/50% on this as a cause though.
QuoteQuote from: amptramp on Today at 08:11:30 AM
A couple of thoughts:
1. The NE555 itself is known for its current spikes when switching between high and low states. You might need more bypassing right at the IC to limit the noise from the current spike. There is a CMOS version of this device that could drive a Darlington transistor or small power MOSFET to reduce the required output current.
2. The noise from the coil itself is due to the rate at which the current rises and falls. A capacitor to ground at the switching transistor base may reduce the inductive kick when the coil turns off and the current ramp when the coil turns on. Splitting the base resistor into two equal series resistors and placing the cap to ground from their junction may let you get away with a smaller capacitor.
1/ you mean the ICM7555, LMC555 or TLC555 i think, interesting, too bad i have 25x NE555, i should order few ICM7555 to try
2/ what kind of cap are you thinking of? I tried with a 100nF film, that does not affect the popping thing
The idea behind filtering the switching circuit is it would also filter the NE555 circuit.
(A 100nF cap is good for the NE555.)
As an ultimate isolation experiment, don't use your existing circuit at all. Get a battery and power the relay coil on its own. Leave the relay diode in and the relay series resistor. Just watch out about getting the supply around the correct way otherwise you might fry the diode. That will completely remove any artifacts from the power supply and the NE555. If it were my circuit I would doing this test. You need to get it to work with this simple set-up before you can continue.
Here's an idea which might help stop the glitches from the switching circuit getting into the audio *via* the relay. Given you can't shield the contacts from the relay structure the next best thing is to slow down the signals which switch the relay. You can see the addition of a 100nF cap (C2) across the collector and base of the relay transistor:
(https://i1004.photobucket.com/albums/af166/ronaldvdboon/Relaysbypass.png)
RG's circuit has the same idea (although for a different type of relay),
(http://www.geofex.com/FX_images/ltchrly.gif)
Quote from: Rob Strand on April 07, 2022, 06:33:12 PM
Quotei tried to use 2 differents (basics) power supply to feed the FX circuit and the relay bypass circuit. Still popping at high level of output volume setting on the FX (but only during silence or low level playing, maybe the pop is hidden/masked when i play louder, but i don't hear it)
So are you basically saying it is better than before?
Also, is the click still happening on both changes in state ie. effect off to on and effect on to off.
If so then the supply filtering might be on the right track.
Ideally the switching circuit (the whole thing) should have its own ground which is run back to the supply input. Lookup star grounding. Its possible to get glitches on the grounds. I only 50%/50% on this as a cause though.
No, sorry, it's not better with seperated power supplies
the click happen during both changes, on and off.
Quote
QuoteQuote from: amptramp on Today at 08:11:30 AM
A couple of thoughts:
1. The NE555 itself is known for its current spikes when switching between high and low states. You might need more bypassing right at the IC to limit the noise from the current spike. There is a CMOS version of this device that could drive a Darlington transistor or small power MOSFET to reduce the required output current.
2. The noise from the coil itself is due to the rate at which the current rises and falls. A capacitor to ground at the switching transistor base may reduce the inductive kick when the coil turns off and the current ramp when the coil turns on. Splitting the base resistor into two equal series resistors and placing the cap to ground from their junction may let you get away with a smaller capacitor.
1/ you mean the ICM7555, LMC555 or TLC555 i think, interesting, too bad i have 25x NE555, i should order few ICM7555 to try
2/ what kind of cap are you thinking of? I tried with a 100nF film, that does not affect the popping thing
The idea behind filtering the switching circuit is it would also filter the NE555 circuit.
(A 100nF cap is good for the NE555.)
As an ultimate isolation experiment, don't use your existing circuit at all. Get a battery and power the relay coil on its own. Leave the relay diode in and the relay series resistor. Just watch out about getting the supply around the correct way otherwise you might fry the diode. That will completely remove any artifacts from the power supply and the NE555. If it were my circuit I would doing this test. You need to get it to work with this simple set-up before you can continue.
Quote from: Rob Strand on April 07, 2022, 06:51:58 PM
Here's an idea which might help stop the glitches from the switching circuit getting into the audio *via* the relay. Given you can't shield the contacts from the relay structure the next best thing is to slow down the signals which switch the relay. You can see the addition of a 100nF cap (C2) across the collector and base of the relay transistor:
(https://i1004.photobucket.com/albums/af166/ronaldvdboon/Relaysbypass.png)
RG's circuit has the same idea (although for a different type of relay),
(http://www.geofex.com/FX_images/ltchrly.gif)
I think you've got something there!
I tried with
- a 100nF, then a 470nf => still the same pop
- 1uF => It clearly removes the trebly part of the pop.
I used an alternative routing for the cap which gave me better results :
(https://i.postimg.cc/3y5BV5gv/2022-04-08-03h45-48.jpg) (https://postimg.cc/3y5BV5gv)
I then tried with an electrolitic 10uF cap, it even better, the pop is has "almost" disapeared !
At the end, with a 47uF electrolitic, there a 0.5second release whistle, that's defenitly the limit you dont want to reach.
The 10uF electro cap win the popping race!
As it's still not perfectly silent, the switching pop is now really acceptable, far from the "click" it was!
Great tip Rob, thanks a lot!
Still have to work on the seperate ground trace for the switching circuit i guess?
QuoteI then tried with an electrolitic 10uF cap, it even better, the pop is has "almost" disapeared !
At the end, with a 47uF electrolitic, there a 0.5second release whistle, that's defenitly the limit you dont want to reach.
The 10uF electro cap win the popping race!
As it's still not perfectly silent, the switching pop is now really acceptable, far from the "click" it was!
Great tip Rob, thanks a lot!
Wow they are very large caps which will result in very slow switch times (as you have seen).
QuoteStill have to work on the seperate ground trace for the switching circuit i guess?
Quite possible this could still be the cause.
As for whistle. That could also be an indication of yet another problem. I was actually going to add this to my previous post but I held off in order to keep the post simple. However, the fact you mentioned whistle means you have this issue to some degree. What the switch time is slow the relay will take longer to close. This means the effect input is open circuit for a short time which then promotes oscillation in high gain circuits.
If you look at this schematic,
http://www.generalguitargadgets.com/pdf/ggg_bmp_tri_sc.pdf
You can see the equivalent of your FXIN line has a 100pF cap (C15) to ground. This helps prevent oscillation/whistle. So it might be wise to try adding it. A value of 47pF to 1nF is often used. It needs to be large enough to stop the oscillation but not so large as to affect the tone. Maybe try 220pF to 470pF.
You might want to check this cap value by making sure there is no whistle in your 47uF case. After that see if you can use a smaller cap to reduce the click (just in case the oscillation is causing the click, which is possible).
FYI, when you get obscure problems like this it's pretty normal to have to dig deeply into the problem. Sometimes that makes you rethink what is actually fixing the problem. There's a lot of reasons under the hood for this stuff and they aren't so easy to explain. Fortunately tracking down the problem can be helped by some experiments and perseverance.
QuoteI used an alternative routing for the cap which gave me better results
You might be better off connecting the cap to ground instead of back to the switch input.
What this is doing is slowing down the signal to the relay - it could even be doing more than that!
QuoteStill have to work on the seperate ground trace for the switching circuit i guess?
It's possible. At the moment the fix can hide many sources of the problem. I'm not exactly sure what
that source is yet.
QuoteQuote
Still have to work on the seperate ground trace for the switching circuit i guess?
It's possible. At the moment the fix can hide many sources of the problem. I'm not exactly sure what
that source is yet.
I guess what I should add is, supposed the click is due to the ground layout. Then while the things you have tried seem like they they are moving in the right direction we are actually solving the wrong problem. We are just reducing the true problem using indirect means.
Quote from: jackwithoneye on April 07, 2022, 09:24:34 PM
I used an alternative routing for the cap which gave me better results :
(https://i.postimg.cc/3y5BV5gv/2022-04-08-03h45-48.jpg) (https://postimg.cc/3y5BV5gv)
I'm not sure if NE555 would like a 10μF, with no series resistor, on its output.. :icon_wink:
With your alternative routing, you may need to use a non-polar cap because the voltage across it changes polarity. If you used a cap from coil to ground, you do not run into this problem.
Could you not just feed the relay coil +supply via an RC filter?
The R of the filter sets the hold voltage with the coil DCR when the relay needs to be on.
The C of the filter sets the duration of the relay pick pulse It will charge to the full +supply voltage when the relay is off.
The hold voltage can be lower than the relay pick voltage. 5v relay might hold as low as 3v. Hold current can be lower.
The momentarily higher +supply voltage than the coil rating when picking is probably harmless as it's only of short duration.
The current stored in the C provides the peak current to pick the relay, not the + supply.
When turned off, the C charges up again for the next pick, the R slows the charge rate avoiding a pulse of current.
Again, thanks for the brainstorming guys!
Rob, i'm sorry, i may have not explained correctly the whistle, i was talking about wasn't really a whistle, more like a Starwars light saber switch off (zzeeeewwww), maybe the discharging cap with the led struggling slowly.
I now understand that this glitch solution is not really healthy, and not sal problem source.
It's really hard for me to understand the concept of seperate ground traces, as the connect together at a point, and even if it's at the DC power connector, i don't understand how it wouldn't go to the audio Jack connectors ground. I don't get the layout technique/workflow to optimise this.
Quote from: amptramp on April 08, 2022, 08:13:33 AM
With your alternative routing, you may need to use a non-polar cap because the voltage across it changes polarity. If you used a cap from coil to ground, you do not run into this problem.
putting a C14 10uf electro cap to ground like on the below picture helps a bit on the SWITCHING OFF popping.
(https://i.postimg.cc/HVvtgmWP/2022-04-08-16h29-09.jpg) (https://postimg.cc/HVvtgmWP)
to do list :
-try using a low current LED
-try using a ICM7555IPAZ instead of the NE555, to avoid the well known NE555's current peak spike when switching state.
-use a 3PDT :icon_lol: :icon_lol: :icon_lol: :icon_lol:
Quote from: anotherjim on April 08, 2022, 08:26:31 AM
Could you not just feed the relay coil +supply via an RC filter?
The R of the filter sets the hold voltage with the coil DCR when the relay needs to be on.
The C of the filter sets the duration of the relay pick pulse It will charge to the full +supply voltage when the relay is off.
The hold voltage can be lower than the relay pick voltage. 5v relay might hold as low as 3v. Hold current can be lower.
The momentarily higher +supply voltage than the coil rating when picking is probably harmless as it's only of short duration.
The current stored in the C provides the peak current to pick the relay, not the + supply.
When turned off, the C charges up again for the next pick, the R slows the charge rate avoiding a pulse of current.
i think rob was speaking about working on the power supply part too, i have to dig into it too
NB: After testing at loud Volume and analysing, i can affirm that as soon as you got a signal in the audio path, there is no popping when switching(not even hidden in the audio signal)
Quote from: jackwithoneye on April 08, 2022, 10:39:47 AM
After testing at loud Volume and analysing, i can affirm that as soon as you got a signal in the audio path, there is no popping when switching(not even hidden in the audio signal)
If so, you need a make-before-brake switch.. :icon_biggrin:
(for signal continuously present on contact lugs)
Quote
Quote
Quote from: anotherjim on Today at 08:26:31 AM
Could you not just feed the relay coil +supply via an RC filter?
i think rob was speaking about working on the power supply part too, i have to dig into it too
You should be able to get Jim's idea to work as well. The idea behind using caps around the transistor is it requires smaller caps to achieve the same job, more or less.
Just to summarize the likely causes:
- changes in current from the relay causing glitches on the power
- change in current from the relay causing glitches on the ground
- the change in voltage on the relay coil coupling through to the contacts (inside the relay)
Slowing down the drive to the relay tends to reduce all of those but it doesn't tell you the cause.
I guess my beef is *if* the problem is noise through the ground we are solving the wrong problem. We would be putting in a heap of filtering to slow things down when really moving a few ground wires will improve things by a factor of 10 or 100. Moving the ground wires might still not be enough but it will certainly reduces the amount of filtering required.
QuoteIt's really hard for me to understand the concept of seperate ground traces, as the connect together at a point, and even if it's at the DC power connector, i don't understand how it wouldn't go to the audio Jack connectors ground. I don't get the layout technique/workflow to optimise this.
Before doing that, in order to workout if it's noise on the ground or glitches through the relay itself the best way forward is to power the whole switching circuit and relay from a separate power supply. You don't want any connections between the ground or power rails of the "new" power supply and the existing effects power. The only wires that connect between the two are the relay *contacts*. This way the switching and switch power are completely out of the picture. If you get glitches then it must be coupling in inside the relay from the coil to the contacts.
The next step would be to keep this configuration and run a single ground wire between the ground of the switch circuit and the ground of the audio circuit. No current should flow down the ground wire. What this test can do is make the coupling between the relay and audio worse (and easier to detect) but it does this without glitches on the power and ground.
If either of these tests show glitches then the coupling is inside the relay and the only hope to remove the ticks is to slow down the signals to the relay.
Continuing on, the next step is to power the switching circuit from the same supply as the audio. This is where is can get complicated because I don't know how you have your power set up.
- Can your pedal be powered from battery and external power?, or does it just have an external power jack?
- Does your input socket (or output socket) switch the effects power off?
The aim of this step is to make sure we don't make the glitch worse. We want to make sure glitches on the power and/or glitches on the ground don't change or increase the glitch. That would point to multiple causes.
QuoteRob, i'm sorry, i may have not explained correctly the whistle, i was talking about wasn't really a whistle, more like a Starwars light saber switch off (zzeeeewwww), maybe the discharging cap with the led struggling slowly.
OK got it. Sometime later it occurred to me it could be that. Relays do that when the current sits around the on/off point too long.
thanks for this great recap, it helps a lot, and my understanding is getting better :icon_lol:
One thing i may have be clear about,...again...my fault..., is that my FX circuit is breadboarded, and the switching circuit is half-breadboarded (the relay itself is breadboarded, connected with wires to a pcb i made for the 5V relay, which has different footprint). It will be easy to power up the 2 circuit with different power supplies, i've done it, by i may have missed a thing, since the audio was trash when i did that, so i was not able to really test anything. I'll redo it more carefully.
I will fully breadboard the switching circuit for the rest of the experiments.
Since i'll have no time for the next 2 days, i'll get back to you asap, with new datas!
Thanks again.
NB; Ive boxed the pcb i've done with the
The constant current draw is going to be an issue for any single-action relay. It's the problem that made me go down the path of latching relays. These are pulsed on and pulsed off, and can be made to draw no current between changes. They still have the problems associated with clicks in the circuit like single action relays do unless you go tricky. In my case, tricky meant filling a 100uF cap through a resistor to supply the pulse for on and off, and being really careful to not let any of the current in the path from cap to coil to transistor and back to cap circulate in the circuit power or ground traces. The resistor-cap isolation trick and double coil relay pretty much solves the issues with constant on-current.
The tricky part also needs a circuit to pulse the "on" and "off" driver transistors. There is an earlier version of this circuit on geofex, but today I'd use an 8-pin microcontroller. Pulse on/off relays also offer some relief on the relay voltage issue. A 5V relay can be used with a 9V pulse that goes off in a short time because they don't have time to heat up.
I should've brought that up earlier, R.G...I NEVER will use a relay for this purpose unless it's a DPDT latching variety with TWO coils. SO much easier to deal with!!! I found a type I like and bought about 20 of them, all set. They work on a pulse, very easy to control. Use anywhere...pedals, amps....
I finally found time to get back to work on this circuit, and breadboarded all the relay switching circuit from scratch.
Quick recap :
-FX circuit is a Tone bender like with npn transistors
-Switching circuit : 9V Relay (ry9wk, non-latching, 540ohm coil)+ ne555
(https://i.postimg.cc/yJvvS3YH/2022-04-13-23h50-13.jpg) (https://postimg.cc/yJvvS3YH)
Power consumption is now ok with this 9V non-latching relay (for FX+switching : more or less 39mA when switched on, and 10mA when off) and i like the fact that when the circuit/pedal is not powered, it comes back to true bypass
ISSUES :
-popping/ticking when switching when there's no audio
-bouncing/triggering
TESTS :
- I ran some tests with seperated/independant power supplies for the circuits, and it still popping when there is no audio volume. I'd seperated "audio ground" and "switching ground" as long as i could on the breadboard, until they join at the power connector. Confirming that it could come from coupling inside the relay itself or power glitches, i guess?
- i'd improve the power supply part with Rob's recommandation : +9V ---diode ---- 100uF to ground [this rail to switching ckt pwr] ---> 100R ---> 100uF to ground [this rail to effect power]
didn't improve popping
- I have a bouncing problem on the triggering (about 5-10% of the time, was a lot less when it was on pcb), tried to find the right R1/C1 combination, but 220K/220nf remain the most reliable, but not enough....
-I also tried to put some 100nF grounded cap in different places (coil, transistor base) but still, no real improvement.
I'm a little bit lost to be honest. I hesitate to startover with new schematic which would be easier to manage
or go back to 3pdt but , i really like the soft touch footswich feeling :
After spending more than 100$ in relays and ne555 and stuffs, i would appreciate to get it working
Dual coil latching relays are pretty hard to find and expensive where i live in europe. (about 6-7$ to get one).
I have no skills at all in coding a PIC (to substitute ne555) to command a relay
Upfront, I want to be very clear that the ground on the relay contact (relay pin 6) should *not* connect to the ground on Q1's emitter/C1/IC pin1. Such a connection will make it hard to separate the possible causes in the list I wrote in the summary. In fact with that connection you might not ever be able to solve the click problem. You should think of relay pin 6 as belonging to the audio/effect circuit.
It would be very helpful if you can spell-out what you had here in your tests. If relay pin 6 was on the switching circuit ground then the best thing to do would be to redo the tests with relay pin 6 connected to the audio ground.
Whatever the test configuration relay pin 6 should always be connected to the audio circuit.
QuoteTESTS :
- I ran some tests with seperated/independant power supplies for the circuits, and it still popping when there is no audio volume. I'd seperated "audio ground" and "switching ground" as long as i could on the breadboard, until they join at the power connector. Confirming that it could come from coupling inside the relay itself or power glitches, i guess?
Excluding my opening caveat that would be the conclusion. However when you say,
Quote
I'd seperated "audio ground" and "switching ground" as long as i could on the breadboard, until they join at the power connector.
It makes me think the ground wiring isn't correct.
The starting point in the test is a configuration where no grounds between the two parts of the circuit (other that relay pin 6). After that you start changing the setup.
Quote- i'd improve the power supply part with Rob's recommandation : +9V ---diode ---- 100uF to ground [this rail to switching ckt pwr] ---> 100R ---> 100uF to ground [this rail to effect power]
didn't improve popping
Using separate power supplies *should* make that filtering unnecessary. However, in the final solution (when we get there) it is almost certain a filter (or filters) will be required. The stuff RG posted is along the same lines.
The reason is the changes in current from the relay will cause voltage the *incoming* power supply to dip. No matter how perfect you do the power wiring and ground wiring you can't stop that dipping. So instead we must add filtering to the supply to hide it.
Quote- I have a bouncing problem on the triggering (about 5-10% of the time, was a lot less when it was on pcb), tried to find the right R1/C1 combination, but 220K/220nf remain the most reliable, but not enough....
I'm not convinced the time constants in the circuit are long enough to debounce the switch. You can try increasing R4 and R5. Try a very large value like 220k or 470k for each.It needs a closer look. The R4 and R5 changes aren't it.
OK, pin 4 is open. Connect it to pin 8.
Quote-I also tried to put some 100nF grounded cap in different places (coil, transistor base) but still, no real improvement.
At this point there might be bigger issues.
Editted
Quote from: Rob Strand on April 13, 2022, 07:21:42 PM
Upfront, I want to be very clear that the ground on the relay contact (relay pin 6) should *not* connect to the ground on Q1's emitter/C1/IC pin1. Such a connection will make it hard to separate the possible causes in the list I wrote in the summary. In fact with that connection you might not ever be able to solve the click problem. You should think of relay pin 6 as belonging to the audio/effect circuit.
Yes, i've been doing this, it was clear in my mind that relay's pin 6 is part of the "audio circuit ground"
Running seperated power supplies (and fully seperated grounds on two differents breadboards) for FX and Switching circuits gives me a buzz/noisy in the audio circuit. However, i just put the FX volume at zero to have silent FX output and certify there's still the pop/tick when switching. (same when the FX part is not powered at all)
Joining grounds at the DC/Jacks grounds make the Audio path clean, but still popping when switching.
It makes me think that the pop/tick is coming wether the relay contact coil coupling or the current peak on the NE555 state change.
In the ideal PCB trace routing ground for pcb design, correct me if i misunderstood, because i might not get right the concept (kind of star grounding?):
-I would use a ground plane on the pcb for the audio Path ground, including to an "Audio Ground pad", which would not extend to the part where the relay coil is, to avoid coupling.
-I would make a "Switch ground" trace joining all the switching circuit grounds (except Relay pin 6!) which would lead to a "switch ground" pad
-Connect the "switch ground pad" and the "audio ground pad" to the DC connector ground.
-Having In&Out jack sleeves connectors directly connected to the audio ground plane through dedicated pads and not to the DC connector.
I would filter the audio circuit and relay switching power supplies separately.
(https://i.postimg.cc/D02p1P10/relay-power.png)
R1 is chosen as 1/10th of the relay coil resistance. It doesn't implement reduced hold current so it doesn't affect the 555 timer latch. For reduced old current, another RC network can be inserted into the feed to the relay coil after C2.
A.J. is right - the filtering you need for the relay coil and switch transistor is different from what you need for the rest of the circuit.
With relays, it's possible to do all the usual things wrong and get clicks and pops. The relay adds two new ones. These are inducing power line and ground transients to the analog circuit power line with sudden current needs, and capacitive coupling of the (large) voltage change across the coil into the audio signal line you're running through the relay.
Let's do capacitive first. It's easiest to understand, but maybe hardest to do anything about. You want your audio signal to be without clicks and pops when there's no audio signal through it and the amps are turned up to ear-bleed volume. The wires the signal run on have impedances at each end - a 1M-ish one at the pedal parallel and the pickup at the other. We'll model the pickup as a 1H to 2H inductor paralleled by 4K to 20K of wire resistance. The fact that it's inductive (and distributed-capacitive) mean it has a high-ish impedance at the high end of audio, and that all is paralleled to the summed-up cable capacitance. That is a modestly complicated network, but we can ignore the cable capacitance and think only of the inductance sending a signal voltage to the 1M input. This is a gross oversimplification, but it's useful to understand. That cable also has a capacitance to ... everything that's conductive in the entire universe. That capacitance trails off as the inverse of the square of the distance from the signal metal to [whatever else]. It's an unwanted input capacitance.
Any voltage change on the outside of that stray capacitor gets coupled through as (oversimplifying again) a high passed signal through the small stray capacitor and the 1M/1-2H/cable capacitance/etc. In any real setup, there's a lot of attenuation, but the attenuation gets smaller as the frequency gets higher.
Run an input signal through a relay, and you're putting part of your signal wire very, very close to a coil of wire that you are going to whack with 5V to 9V of coil voltage, then release. The turn-on voltage appears full voltage, then sags for micro- or milli-seconds as the coil voltage rises. At turn off, the voltage rises semi-instantaneously from just the resistive voltage across the coil to the power supply plus the flyback voltage of the relay coil. Very fast signal edge, couples well across the stray capacitance to the signal wires in the relay.
Without a shielded relay, you're not every going to make the coupled signal go to zero. You can make it smaller until it's not noticeable by slowing down the voltage rise and fall. Ideally, you'd try some kind of current ramping up/down on the relay coil. I've tried that. It works, but it's complicated. The one-transistor integrator from the geofex circuit work well enough to suppress coupled relay coil ticks down to the units of millivolts. That turned out to be not objectionable to me, my boss, or our customers, so we went with it. You have to turn the amp up and put your ear near the speaker to hear this in most setups. A theoretically better solution would be to make the signal line impedance be much lower, as this would make the stray capacitor have to move a lot more current to get the signal voltage to change, but high impedance signal lines on inputs is what we have to have for other reasons. So lower signal impedance levels isn't really a practical answer.
Power supply transients from turning the relay coil on and off can be a little baffling. After all non one has an isolated power supply in a pedal, do they? So the relay has to share ground somewhere, even if it's just star grounded back to the power supply.
What has worked for me is a variant of what I was describing before and what A.J. was getting at - isolating the relay coil current loop.
We don't much care, within some limits, what the DC conditions are. We just want sudden current edges, both on and off, to not cause +9V (or 12, or whatever) to tick up and down, and we really don't want those same spikes to raise and lower ground, as that sends a <tick> directly into our circuit inputs. We can "isolate" our relay ground from analog/signal ground by making the relay coil current really, really want to stay in a nice tight loop from a capacitor near the coil, through the coil, and back to the capacitor - and not back to audio ground.
Take a resistor from(for instance) +9V to the + end of a cap, ground the other end of the cap. If we hook the relay coil and series switch transistor across that cap, then turning the transistor on and off operates the relay. The cap charges up to 9V when the relay is off, provides the current for the coil when the transistor is turned on, and does not suck transients from the power supply. The charge stored in the cap >wants< to go back to that cap, not the shared power supply.
When you turn the transistor on, cap voltage appears across the coil. The coil current ramps up at a rate governed by the inductor equation, V = L * di/dt. At the time just after the switch turns on, the cap voltage is still 9V, the coil voltage is 9V, but the current has not ramped up from zero. As the milliseconds plod on, the inductor current ramps up at di/dt = V/L, and the capacitor voltage, governed by I = C* dV/dt ramps down. If the cap was not there, the current would have to come through the power supply wire resistance and return through the ground path to the power supply.
With the cap there, the current into the coil is ramped up, the cap voltage is ramped down, and the difference between the analog power 9V and the capacitor voltage increases through the series resistor to the cap. So a slowly increasing current from the analog power supply voltage into the resistor/cap/relay circuit happens, and juggling the resistor and the cap you can make this voltage change on the analog power supply as slow as you want. What you want is to have this voltage change to have a frequency content below audio, or below the pass band of your pedal and amp. If that's true, you will not hear a transient.
What about the ground current? Won't it make a tick? Maybe. You can often get away with a gimmick, a low-ohms resistor in series between the capacitor negative and the main circuit ground. I've only had to do this once over the years. Setting up a nice, tight, everything-side-by-side circuit for the relay coil, switch transistor, decoupling cap and resistor(s) can often be magic. But it still won't make the transient be zero - just unnoticeable.
Well, I see I just set off typing again. Ask questions about what is muddy.
Oh, and get rid of that 555. Just do it. Use a CMOS 7555 equivalent. Just do it. Some 555 circuits can never be quieted, and I've tried.
wow, just wow
Thanks for your time, that's wonderfull to have all you guys helping me with that kind of precious knowledge.
I have to re-read all this few(thousands) times, to get back with not "too" dummy questions, because it's way above my skills. I want to learn, so i'm to trying to understand the most i can. Because right now, i just dont know how to integrate this and link it with my circuit. I'll try AJ's power setup asap
I guess that the fact that everything is breadboarded doesnt help with capacitance management.....
I'll get rid of the ne555, that i get. I'll buy a bunch of the cmos version ICM7555IPAZ. (that's the easy part :icon_lol: :icon_lol:)
datasheet : https://www.renesas.com/us/en/document/dst/icm7555-icm7556-datasheet
QuoteYes, i've been doing this, it was clear in my mind that relay's pin 6 is part of the "audio circuit ground"
OK, great.
QuoteRunning seperated power supplies (and fully seperated grounds on two differents breadboards) for FX and Switching circuits gives me a buzz/noisy in the audio circuit. However, i just put the FX volume at zero to have silent FX output and certify there's still the pop/tick when switching. (same when the FX part is not powered at all)
Joining grounds at the DC/Jacks grounds make the Audio path clean, but still popping when switching.
The buzz problem is a different issue. It's common on breadboards. There's plenty of ways to reduce it. For example, shielded wires on each of the relay contacts then connect the both shields to audio ground and only one of the other ends to relay pin 6. You can also sit both breadboards on a metal sheet (aluminum foil works) connected to audio ground. Some breadboards have an aluminum backing already - I ground this more often than not. You can experiment with these if you like as it's common issue with breadboard. However, it's more for your own interest and it's probably not to help your click (it could help a small amount).
QuoteIt makes me think that the pop/tick is coming wether the relay contact coil coupling or the current peak on the NE555 state change.
I don't think it's the NE555 but to *prove* it you can wire a switch to the base transistor resistor, the switch supply rail and ground. In effect replacing the NE555 output with a switch.
You should also try another experiment where you replace the relay contacts with a switch. The reason is it proves your current set-up can work at all. Maybe there's a problem elsewhere. This test will give some peace of mind. It would be really annoying if there's some other bug contributing to the click.
For tricky problems it is a good policy to take a step backwards and *prove* what you think is working actually does work.
Quote
In the ideal PCB trace routing ground for pcb design, correct me if i misunderstood, because i might not get right the concept (kind of star grounding?):
-I would use a ground plane on the pcb for the audio Path ground, including to an "Audio Ground pad", which would not extend to the part where the relay coil is, to avoid coupling.
-I would make a "Switch ground" trace joining all the switching circuit grounds (except Relay pin 6!) which would lead to a "switch ground" pad
-Connect the "switch ground pad" and the "audio ground pad" to the DC connector ground.
-Having In&Out jack sleeves connectors directly connected to the audio ground plane through dedicated pads and not to the DC connector.
That would all be for doing the best you can but if it's going to work then you should be able to follow the diagram anotherjim has kindly drawn up. The physical way the ground and power connections are made should follow anotherjims drawing. For experiment you could add another 100uF cap from where R1 and R2 join back to the common DC input ground at the top left. You could also try powering the LED from the from the other side of R1.
That should be enough to fix any power and ground issues. Your final circuit should keep that configuration as anything less is asking for trouble.
There is still one crack that can cause clicking and that's coupling inside the relay. That's quite possible and I'm thinking even likely. By checking and doing all the above it's essentially proving that's the only cause left to blame.
The problem is coming up with a solution. We can't modify the relay or ground the internals. The obvious solution is to slow down the signal of the collector of the relay transistor. That's kind of where we go upto very early on but we didn't have any proof that coupling through the relay was the only cause. That means adding resistors and capacitors.
Much more sinister solutions involve grounding the relay - terminal and switching the relay + terminal. That would work only for particular relays. The idea is a *particular model* of relay may have more coupling from the - terminal to contacts than the + terminal. So by switching the + terminal it reduces the coupling.
It could be worse, the same, or only a little bit better than before. You can only try it and live in hope.
You would need to change the relay drive circuit to so that. At this point I won't clutter the post with details. However as an experiment it would be easier to switch the relay off and on with a switch (as per above experiment).
Slowing down the signal on the collector is kind of forcing success since it has to at least reduce the problem.
The NE555 was a great chip for many things, and revolutionized timer chip use when it came out. But that was at a time when a few pesky current spikes on the power supply didn't matter much. The bipolar 555 can draw >an amp or more< directly from power to ground at the instant it switches. It's kind of a current-mode Molotov %^&*tail.
This might be your problem, or, since there is almost never only one problem, it might only be an accomplice to the crime.
As Rob notes, using a pair of wires to connect/disconnect the relay coil would eliminate the 555's contribution. It's a quick, cheap test. Your description of the click as being very trebly, tick-not-pop, weighs in favor of the stray capacitance inside the relay, again as Rob notes. You could also (sneakily...) disconnect just the input and then just the output and switch it to isolate whether it's from the input signal switching (I found this was more frequently the issue) or the output switching. Or both, equally.
Be very sure that the ticking is not an artifact of a small DC level difference on the output of the pedal, input of the amp, and maybe try different amps. Yep, found that issue before too.
Not to help with jackwithoneye's problem, but for general info:
The April 1967 issue of Electronics World is all about relays. Even Frye's column.
https://worldradiohistory.com/Archive-Electronics-World/60s/1967/Electronics-World-1967-04.pdf
https://worldradiohistory.com/Electronic_World_Master_Page.htm
I realize the schematic drawn by anotherjim is somewhat simplified, but there has to be a base resistor from the timer to the transistor. An R-C network or better yet, an R-C-R network from the timer to the transistor with the C grounded may slow the current rise and fall enough to get rid of some of the problem.
Quote from: amptramp on April 15, 2022, 08:53:23 AM
an R-C-R network
I was interpreting last R as a typo 'till realize you refer on it as cap shunt discharge resistor, Ron.. :icon_redface:
I wasn't interested in the 555 circuit so I didn't show any of it, but I had to show the BJT as it's attached to the relay. The base drive is inside the "Timer" block, natch.
Thing is, the audio circuits are discrete class-A so prone to passing supply rail noise via bias networks into the audio path & amplifying it - so, unless battery powered should have an independently filtered DC supply - relay or no relay.
I'd guessed that Jim's schematic was focused on the power supply & filtering part, with the "timer circuit" as it was set to the bjt. I haven't any results to give yet, cause i fried some part doing other tests due to breadboard glitches. but i will get back to it.
i draw this, based on the Jim's power and grounding supplies drawing
(https://i.postimg.cc/87K8KWXt/2022-04-16-01h51-45.jpg) (https://postimg.cc/87K8KWXt)
How do i choose the R-C-R(R2) values (pink square on the schematic) for slowing current rise?
Correct me if i'm wrong, as far as i understand, i have to do a seperated trace for VD (switching circuit ground) which lead to a pcb pad, connected to the DC connector ground (as for the Audio ground) right?
I'm using Eagle, and it doesn'nt recognize any difference, as GND and VD is the same net, so i have to remove the Audio ground plane on the pcb design where the switching circuit is, to be able to route VD to a seperated pad without ratnest messing this routing.
Quote from: jackwithoneye on April 15, 2022, 08:08:12 PM
Correct me if i'm wrong, as far as i understand, i have to do a seperated trace for VD (switching circuit ground) which lead to a pcb pad, connected to the DC connector ground (as for the Audio ground) right?
I would if I were you.
But I would suggest a BFC* as close to the relay as you can get it, and the switch transistor bridging the gap between the negative side of the relay coil and the negative side of the BFC. Any catch diodes go from the collector of the switch transistor to the positive of the BFC. This circuit lump needs to be as close together and compact, with the shortest possible traces connecting pieces. Don't go all loopy on the traces. A resistor to the general power supply, ideally leading back to the positive pin for power coming onto the PCB and no.where.else. would be a vast help.
*Big Freaking Capacitor
Quote
I'm using Eagle, and it doesn'nt recognize any difference, as GND and VD is the same net, so i have to remove the Audio ground plane on the pcb design where the switching circuit is, to be able to route VD to a seperated pad without ratnest messing this routing.
I don't use eagle, but I have run into this before. Do this: define a dummy component "resistor.ground.isolation" and put it between the general analog ground and the negative side of that BFC. Label the negative side of the BFC something poetic, like "relay ground". The other side of the "resistor" is general power ground, but you will route the trace from the resistor to the board negative power input pad without touching anything along the way.
"resistor.ground.isolation" can be any value, from zero (soldered in wire) to many megs. If you never, ever plan to put a resistor there, you can at the very end of layout when the traces are all done remove the resistor and hard-connect the two "grounds". I would suggest leaving it in and experimenting with values from soldered wire up to 10 or 22 ohms.
But it still might be relay capacitance clicking...
Quote from: anotherjim on April 14, 2022, 01:27:40 PM
I would filter the audio circuit and relay switching power supplies separately.
(https://i.postimg.cc/D02p1P10/relay-power.png)
R1 is chosen as 1/10th of the relay coil resistance. It doesn't implement reduced hold current so it doesn't affect the 555 timer latch. For reduced old current, another RC network can be inserted into the feed to the relay coil after C2.
For info, the relay i use, RY9WK, has, as far i as i know a non-polarized coil, there no particular + or - coil pins on the datasheet
The timer is still NE555, as i haven't received the cmos version yet.
Test 1 : Powered the relay coil independantly, without the timer circuit, straight from an independant power supply+ momentary switch, without filtering
=>still got the tick+pop when switching
Test 2 : I applied strictly, on my breadboard, Jim's power supply filtering above's schematic for the switching&FX, fed from one power supply.
=> Good improvement, stability, buzzing is a lot better.
The switching tick/pop is definitly better, the "tick" is almost gone, but there's still a real pop going through the FX circuit (i can filter it with the high pass in the audio FX circuit)
when switching ON, only.
Power consumption is all good with 24mA when on and 9mA when off.
test3 :
I had tried (maybe in a bad way, due to my misunderstanding? see below schematic) RG's BFC:
tried (in both direction) 100uF,47uF,10uF
It's actually slowing down the relay release (switching off), and making the "Zeeeew" light saber sound during this release, but doesn't affect the switching ON pop.
(https://i.postimg.cc/f3qPRbzR/2022-04-16-19h39-24.jpg) (https://postimg.cc/f3qPRbzR)
i did not implement yet any RCR (like amptramp said) to slow down current rise as i don't have a clue of the values needed, and it might still depend of cmos ne555 (ICM7555IPAZ) that i'll try, right?
And again, big thank you all for helping!
QuoteTest 1 : Powered the relay coil independantly, without the timer circuit, straight from an independant power supply+ momentary switch, without filtering
=>still got the tick+pop when switching
Test 2 : I applied strictly, on my breadboard, Jim's power supply filtering above's schematic for the switching&FX, fed from one power supply.
=> Good improvement, stability, buzzing is a lot better.
Those results don't make sense as jim's circuit doesn't change the switching times. It separates the power and test 1 already *is* separating the power. In test 1 did you have a diode on the relay?
As a sanity test you should try replacing the relay entirely with a normal switch. If that ticks/pops you have another issue which cannot be solved by playing with the relay circuit.
Quotetest3 :
I had tried (maybe in a bad way, due to my misunderstanding? see below schematic) RG's BFC:
tried (in both direction) 100uF,47uF,10uF
It's actually slowing down the relay release (switching off), and making the "Zeeeew" light saber sound during this release, but doesn't affect the switching ON pop.
That connection works better for switching off. When switching on the transistor shorts out the cap so the on-time is fast. The turn-on speed is limited only by the transistor's ability to pass current (set by the base resistor). So basically this circuit has extreme asymmetry in the turn on and turn off times.
To filter both on and off you need different configuration. Unfortunately most simple circuits like that one will end-up with the turn on being somewhat faster than the turn on. You can for example add a resistor in between the relay+diode+added cap and the collector of the transistor. The larger the resistor the slower the turn on time. However, due to voltage drops, the resistor can't be too larger otherwise the relay won't turn on correctly. The other way to make the turn-on time longer is to increase the added cap. However that will also increase the turn-off time. This is where the asymmetry in the on and off times becomes hard to work around.
If you still have the 10k base resistor, it might be worth trying a cap across the base and collector of the transistor again.
Out on a breadboard, I think any switching contacts that are not screened from radiated noise might create clicks in the audio. This can even happen if the noise isn't audible. If there is any stray signal present there is a short time when if the contact voltage is non-zero it gets transferred between paths as stray capacitance holds it momentarily as some random DC level. Ordinary PCB relays don't usually have any screening of the contacts and they are sticking up inside the plastic case like aerials.
(https://electrical4u.net/wp-content/uploads/2020/09/relay-internal-circuit-1.png)
This is the general layout in a PCB relay. Differences might be the coil is rotated 90deg. The contact operating part should be electrically insulated from the armature otherwise the contact capacitance will change between states.
If the coil is in the middle, like the following illustration, it should probably not be used for audio as the common contact is more prone to noise pickup and capacitance changes between states.
(https://i0.wp.com/pi-plates.com/wp-content/uploads/2015/11/NC-RELAY.jpg?resize=768%2C436&ssl=1)
Quote from: anotherjim on April 17, 2022, 10:02:46 AM
Out on a breadboard, I think any switching contacts that are not screened from radiated noise might create clicks in the audio. This can even happen if the noise isn't audible. If there is any stray signal present there is a short time when if the contact voltage is non-zero it gets transferred between paths as stray capacitance holds it momentarily as some random DC level. Ordinary PCB relays don't usually have any screening of the contacts and they are sticking up inside the plastic case like aerials.
(https://electrical4u.net/wp-content/uploads/2020/09/relay-internal-circuit-1.png)
For this relay, if you grounded the right most contact (NC) it would act as a shield. Connecting the terminal to a low impedance output would achieve a similar result. However connecting that terminal to a high impedance input would make things worse. This is along the lines of what I was trying to get at at the end of Reply #47. Except that was aimed at stopping the junk getting out.
The take home message is different relays, different contact choices and different circuits can make or break the performance of the build.
QuoteTest 1 : Powered the relay coil independantly, without the timer circuit, straight from an independant power supply+ momentary switch, without filtering
=>still got the tick+pop when switching
Test 2 : I applied strictly, on my breadboard, Jim's power supply filtering above's schematic for the switching&FX, fed from one power supply.
=> Good improvement, stability, buzzing is a lot better.
Those odd results point to something more going on. If it were mine I'd probably try to unravel the mystery, however, these subtle issues never get solved on forums. Perhaps a better plan is this: In the case where you have separate supplies the idea is the circuits behave independently. For any of the tests, even for the separate supply, add a 100uF to the power supply rail on the audio circuit and a 100uF cap to the power supply rail on the switching circuit. The caps shouldn't be necessary but they should help suppress any secondary weird issues which mess with the results. At least that way we can go forward.
Quote from: Rob Strand on April 16, 2022, 06:57:32 PM
QuoteTest 1 : Powered the relay coil independantly, without the timer circuit, straight from an independant power supply+ momentary switch, without filtering
=>still got the tick+pop when switching
Test 2 : I applied strictly, on my breadboard, Jim's power supply filtering above's schematic for the switching&FX, fed from one power supply.
=> Good improvement, stability, buzzing is a lot better.
Those results don't make sense as jim's circuit doesn't change the switching times. It separates the power and test 1 already *is* separating the power. In test 1 did you have a diode on the relay?
As a sanity test you should try replacing the relay entirely with a normal switch. If that ticks/pops you have another issue which cannot be solved by playing with the relay circuit.
I've tested with a classic mechanical DPDT switch in place of the relay contacts (except the coils contacts of course), it's still getting the tick/pop, even louder than with the relay i think, and during Switching on and off with the mechanical DPDT
I've tested with the "audio" relay contact reverted (meaning that when the relay's coil is not powered- relay in idle position-, the effect is on, and when it's powered, the fx is bypassed). in this position the led is lit when fx is bypassed. Swithching On the fx (coil changing status from powered to unpowered) is still when the pop happens.
Considering these two tests, i tend to think that the relay (and timer circuit) is not generating the tick/pop by itself, when it's changing status, but it would be more likely the effects circuit INPUT changing from grounded(when bypassed) to Jack IN (when FX on) that would generate the pop. Am i wrong in my deduction?
I'm still thinking that some of my false or "make no sense" tests results analysis might be corrupted by the fact that i'm using a little bit "cheap" breadboard and non shielded wires.
Quote
Quotetest3 :
I had tried (maybe in a bad way, due to my misunderstanding? see below schematic) RG's BFC:
tried (in both direction) 100uF,47uF,10uF
It's actually slowing down the relay release (switching off), and making the "Zeeeew" light saber sound during this release, but doesn't affect the switching ON pop.
That connection works better for switching off. When switching on the transistor shorts out the cap so the on-time is fast. The turn-on speed is limited only by the transistor's ability to pass current (set by the base resistor). So basically this circuit has extreme asymmetry in the turn on and turn off times.
To filter both on and off you need different configuration. Unfortunately most simple circuits like that one will end-up with the turn on being somewhat faster than the turn on. You can for example add a resistor in between the relay+diode+added cap and the collector of the transistor. The larger the resistor the slower the turn on time. However, due to voltage drops, the resistor can't be too larger otherwise the relay won't turn on correctly. The other way to make the turn-on time longer is to increase the added cap. However that will also increase the turn-off time. This is where the asymmetry in the on and off times becomes hard to work around.
If you still have the 10k base resistor, it might be worth trying a cap across the base and collector of the transistor again.
Tried differents low values resitors between collector and relay-diode without very good improvements, until the resistors gets too big (above 200R) and begin to mess up with the relay's coil activation.
Tha cap between transistor's base and collector doesn't really help, as it slows down the Switching off, but doesn't reduce switching on's pop. (tried different values, the only thing that changes it the switching of time length)
QuoteConsidering these two tests, i tend to think that the relay (and timer circuit) is not generating the tick/pop by itself, when it's changing status, but it would be more likely the effects circuit INPUT changing from grounded(when bypassed) to Jack IN (when FX on) that would generate the pop. Am I wrong in my deduction?
I don't think you're wrong. The only real way to prove it is to build it and wait and see how it goes in an enclosure. There should be less stray noise around things then.
Don't leave out your power filtering though, it's still wise to protect against possible noise from the DC power feed.
QuoteI've tested with a classic mechanical DPDT switch in place of the relay contacts (except the coils contacts of course), it's still getting the tick/pop, even louder than with the relay i think, and during Switching on and off with the mechanical DPDT
OK, so that has to be solved. There's no hope of getting the relay version to work until that is done. As a double sanity check you could try another DPDT switch. You could try grounding the metal parts of the switch as well. This result pretty much nullifies any testing with the relay because it points to a bigger issue. The puzzling thing is why some of the relay configurations have an effect (perhaps multiple problems are present).
The question is what is causing it. (BTW, I'm not surprised with the result since a lot of these hard to solve problems end up being something else. That something else generally being something that's a pain in the butt for newbies to diagnose.)
This type off issue tends to be caused by DC. It can also be cause by oscillation. Even RF issues.
Make sure you have the resistor (R26) and cap (C15) at the input of your circuit as mentioned before in this post:
QuoteIf you look at this schematic,
http://www.generalguitargadgets.com/pdf/ggg_bmp_tri_sc.pdf
You can see the equivalent of your FXIN line has a 100pF cap (C15) to ground. This helps prevent oscillation/whistle. So it might be wise to try adding it. A value of 47pF to 1nF is often used. It needs to be large enough to stop the oscillation but not so large as to affect the tone. Maybe try 220pF to 470pF.
Maybe the things you are connecting to the input or output have a small amount of DC. Try plugging into something else. For example if you have any pedals which have buffered input and outputs (not true-bypass), like Ibanez and Boss, you can set-up the test like this: Commercial Pedal (bypassed) ---> Your Pedal ---> Commercial Pedal (bypassed).
Bad caps can cause DC issue. Either on your board, or inside whatever you are plugging into. Connecting to phones and PC's can put DC on certain pins. The DC used to power the condensor mic.
QuoteI've tested with the "audio" relay contact reverted (meaning that when the relay's coil is not powered- relay in idle position-, the effect is on, and when it's powered, the fx is bypassed). in this position the led is lit when fx is bypassed. Swithching On the fx (coil changing status from powered to unpowered) is still when the pop happens.
Considering these two tests, i tend to think that the relay (and timer circuit) is not generating the tick/pop by itself, when it's changing status, but it would be more likely the effects circuit INPUT changing from grounded(when bypassed) to Jack IN (when FX on) that would generate the pop. Am i wrong in my deduction?
Definitely, no point messing with the relay circuit. The exact mechanism causing it isn't clear as there can be many causes.
QuoteI'm still thinking that some of my false or "make no sense" tests results analysis might be corrupted by the fact that i'm using a little bit "cheap" breadboard and non shielded wires.
It's quite possible. If you have a lot of interference above the audio range you can't hear how bad the interference is but when you switch it creates a large discontinuity in the waveform and you hear a tick. Same goes for an oscillating circuit. Given the amount of buzz you are reporting that should be put high on the list.
Adding the input cap above and putting a 100uF cap on the power rails can help knock down oscillation. However, there's plenty of other areas for example wires to pots and switches on you pedal can cause oscillation to occur, especially if they aren't shielded.
A big one is it to make sure all your wiring is correct, especially the grounds. If your breadboard has strips on the edges for power makes sure the power is getting through to all parts. Some breadboards have a break in the two side strips at half the way point and you need to add jumper to make the power connect through.
Something that's a little weird to me, and perhaps it's a clue, when you set the output pot to zero you are still getting pop. Setting that pot to zero should prevent DC issues at the output, it stops many oscillation causes, and it reduces the level of interference signal at the output. So that might mean something weird is going on at the input. You could see what happens when you short the input to effects circuit and/or the input while you have the output pot set to zero. See what combination helps if at all.
At this point:
- test with the DPDT switch
- try buffered pedals before and after your pedal.
- Add the input resistor if your don't already have it
- Added input cap
- 100uF on effects power rail
- check power wiring on breadboard
- set output pot to 0
- try shorts on input socket and/or input of effect pedal
You can start grounding the metals parts of pots and ground the aluminium base-plate of the breadboard. These things can only help.
EDIT: I fixed a few typos.
If you do find you are getting problems from the relay coil, it would be interesting to use something like a power door lock actuator for a car to control a toggle switch or microswitch because the coil can be mounted far away from the switch. Added bonus: a power door lock can push and pull, so you could get the effect of a latching relay just by driving the coil in opposite directions. This means you have to use series R-C snubbing across the coil because diodes would short out the drive in one direction. Some mechanisms have two coils to be able to use flywheel diodes across them.
i tried to improve groundings on the breadboards, sometimes it's getting better, sometimes it's still buzzy, i think i'll have to wait until i pcb'd it to really have a clear overview of the situation, because the breadboarding testing results are showing so much inconstancy that i can't give you clear datas to help you helping me ;D ;D
Quote from: Rob Strand on April 18, 2022, 06:16:58 PM
Make sure you have the resistor (R26) and cap (C15) at the input of your circuit as mentioned before in this post:
QuoteIf you look at this schematic,
http://www.generalguitargadgets.com/pdf/ggg_bmp_tri_sc.pdf
You can see the equivalent of your FXIN line has a 100pF cap (C15) to ground. This helps prevent oscillation/whistle. So it might be wise to try adding it. A value of 47pF to 1nF is often used. It needs to be large enough to stop the oscillation but not so large as to affect the tone. Maybe try 220pF to 470pF.
done
Quote
At this point:
- test with the DPDT switch
- try buffered pedals before and after your pedal.
- Add the input resistor if your don't already have it
- Added input cap
- 100uF on effects power rail
- check power wiring on breadboard
- set output pot to 0
- try shorts on input socket and/or input of effect pedal
done all this without clear improvements or variations
I've received the NE555 cmos version, using the ICM7555IPAZ.
It's reducing even more the power consumption, the whole circuit drains only 22mA when ON and 4mA when bypassed.
This timer swap changes the behaviour of the circuit when you plug the power connector.
The relay routes are connected in a way that when the pedal is unpowered (dc connector unplugged) or the pedal is off (coil not powered), the pedal stand in bypass mode.
With the NE555, when you plugged in the power connector (or power your pedal board), the pedal stand in bypass mode until you press the footswitch.
With the ICM7555IPAZ timer, it still automatically switches to bypass when you remove power, but when you plug the power connector back (or switch on you pedalboard power supply), the timer instantly feed the transistor-relay, and power on the effect (which is not really user friendly)
To solve this, i had to remove the pin 8 (V+) and 4(reset) timer junction, as when it was before Rob's #42 posts, which helped for false triggering with the NE555, but not anymore with this cmos version.
I'll make a feedback about buzzing, popping and triggering when i'll have it boxed in about 15 days.
Still, thank you for your support ;)
It just started from a humble power consumption query.. :icon_cool:
Quote from: antonis on April 23, 2022, 11:33:39 AM
It just started from a humble power consumption query.. :icon_cool:
;D ;D ;D ;D Well, that escalated quickly ;D ;D ;D
To resume : The power consumption query had been solved using a higher coil resistance relay and get rid of the ne555 for a more power efficient cmos version.
The rest is just great dedication from all the participants and this great community, teaching me a lot, and (still) helping me understand and improve my circuit. :heart:
Quote from: jackwithoneye on April 22, 2022, 06:01:11 PM
i tried to improve groundings on the breadboards, sometimes it's getting better, sometimes it's still buzzy, i think i'll have to wait until i pcb'd it to really have a clear overview of the situation, because the breadboarding testing results are showing so much inconstancy that i can't give you clear datas to help you helping me ;D ;D
...
done all this without clear improvements or variations
You can wait and see. If the problem is related to your breadboard-build then the PCB will solve that in one foul swoop. The problem then is if it doesn't then there's going to be some patches on the board. It's even possible the problem is external to your build.
The click/pop was still present when you tested with only the switch. That points to something not related to the relay switching circuit. However the fact you can make changes to the relay circuit and it changes the click/pop goes against that conclusion. Weird behaviour like this is a sign there's bigger issues involved.
You would need to start from a very dumb simple circuit then gradually build it up. If that doesn't work then you have to wire up an even simpler circuit. You need to starting point which least works no matter how stupid it looks. Then make small changes. When it breaks work out why. It's lot easier to see problems in a ridiculously simple circuit. In the full circuit there's too many things to "blame".
For example,
- test with mechanical switch, no relay.
- remove the pedal part all together
- instead of connecting switch wire to the input of the pedal circuit connect it to ground.
- instead of connecting switch wire to the output of the pedal circuit connect it to ground.
Obviously, there will be no effect but the what we are looking for is not click/pop.
Next,
- try wire those switch to different ground points. Is there any change?
- instead of connecting the input wire to ground, wire the input to ground via a 1M resistor
- any change?
- connect input wire back to ground
- now, instead of connecting the output wire to ground, wire the output to ground via a 100k resistor
In theory these dumb connections should be OK, if not ... you have some problems to sort out. Try playing with the resistor values. Lower should have less problems. Measure the DC across them (even 1mV will cause a pop).
After that you could for example replace the pedal with a simple one transistor buffer and see if you
can switch that in and out without click/pop. (You will need anti-pop resistors on the input and output.)
The process of building up the circuit continues until it breaks.
QuoteI've received the NE555 cmos version, using the ICM7555IPAZ.
It's reducing even more the power consumption, the whole circuit drains only 22mA when ON and 4mA when bypassed.
This timer swap changes the behaviour of the circuit when you plug the power connector.
The relay routes are connected in a way that when the pedal is unpowered (dc connector unplugged) or the pedal is off (coil not powered), the pedal stand in bypass mode.
With the NE555, when you plugged in the power connector (or power your pedal board), the pedal stand in bypass mode until you press the footswitch.
With the ICM7555IPAZ timer, it still automatically switches to bypass when you remove power, but when you plug the power connector back (or switch on you pedalboard power supply), the timer instantly feed the transistor-relay, and power on the effect (which is not really user friendly)
To solve this, i had to remove the pin 8 (V+) and 4(reset) timer junction, as when it was before Rob's #42 posts, which helped for false triggering with the NE555, but not anymore with this cmos version.
As for the power-up state, on-paper I don't think that circuit can be guaranteed to power up in a particular state. Normally 555 circuits have caps which force the state at power up but that circuit is in a 'hanging' state from the start. From what I can see there's nothing in the NE555 or the ICM7555IPAZ datasheets mentioning the power-up state. Unofficially, there may be something about the chips that does make them power-up in a particular state. On the other hand you might be able to get 10 NE555's from different batches and manufacturers and they all power-up in different states.
As for the bouncing, that seems weird. The pin 4 to pin 8 connection is required to ensure reliable behaviour on both Bipolar and CMOS 555's. The basic behaviour of the switching circuit should not show more tendency to bounce on either type of device. One difference between the Bipolar and CMOS is the impedance on pin 5. The CMOS devices typically have a higher impedance making it more susceptible to noise. My only suggestion is to try adding cap, say 10nF to 100nF fro pin 5 to ground.
This problem with the 555's might be also be related to your click/pop issue. If you have an enormous amount of noise in the circuit you will be getting all sort of strange behaviour. Click/pops on the audio, bouncing on the switch circuit. Your problem could even be related to the power supply you are using. Noise can come in from the mains through to the power supply output. Also some power supplies can oscillate at high frequencies under light loads - that would cause all sorts of headaches.
There's always plenty of speculative theories with this stuff and you can only carrier out a lot of tests and measurements to put a tighter box around the possibilities. A lot of the weird problems that come-up from time to time are extremely difficult to visualize and debug - almost impossible for a newbie.
QuoteThe basic behaviour of the switching circuit should not show more tendency to bounce on either type of device.
Actually there's one major difference between the between the Bipolar NE555 and the CMOS ICM555, that's the output swing on pin 3. The high output on the Bipolar 555 swings to less than full supply whereas the CMOS 555 swings to full supply. The CMOS version should act more symmetrically in this respect whereas the Bipolar version might bounce different when going on to off compared to off to on. (I wrote down some detailed equations for that circuit a while back. They would help quantify things but I don't think it's going to explain the behaviour).
Hi
Thanks Rob for your last posts ( i haven't been through the different tests worflow you're suggesting yet)
Here is the situation today :
I've pcb'd and boxed the circuit with the Clean bifurcated and filtered power supply mentionned before. FX and Switch Ground traces isolated.
So far, it changes a lot of things comparing to my cheap breadboards setup:
- The circuit is super quiet, no buzz, noise, parasites. It's really really clean (the fx circuit is a tonebender-like, i used to hear a lot more noise in this kind of circuit). Even when i put the guitar volume pot at zero (which Tonebender circuits usually don't like) and it's really silent. Super happy with that.
- The switching noise problem is a lot better than on the breadboard,
no pop at all (tried different amps and guitars),
only a very little tick when switching off mostly (relay coil unpowering).
- Trigger Bouncing is rare, and happens mostly when i press the momentary footswitch very slowly through the contact point of the switch, but sometime even when it quickly pressed by foot. Hard to determine if it's a mechanical switch bouncing, or an electronical source.
- Power consumption initial problem is handled, with differents changes we talked earlier (low consumption timer and higher relay coil resistance)
Quote from: Rob Strand on April 26, 2022, 07:57:40 PM
QuoteThe basic behaviour of the switching circuit should not show more tendency to bounce on either type of device.
Actually there's one major difference between the between the Bipolar NE555 and the CMOS ICM555, that's the output swing on pin 3. The high output on the Bipolar 555 swings to less than full supply whereas the CMOS 555 swings to full supply. The CMOS version should act more symmetrically in this respect whereas the Bipolar version might bounce different when going on to off compared to off to on. (I wrote down some detailed equations for that circuit a while back. They would help quantify things but I don't think it's going to explain the behaviour).
interresting, i'll try to grab some oscilloscope screenshots of these differences on the pin3 output, it might confirm that right?
Quote from: jackwithoneye on April 27, 2022, 09:45:40 AM
- The switching noise problem is a lot better than on the breadboard, no pop at all (tried different amps and guitars), only a very little tick when switching off mostly (relay coil unpowering).
The tick noise is probably the relay's movable contact changing positions. It is a mechanical noise and is always going to be there. I don't know of any way to get rid of it other than soundproofing the relay package itself. :icon_eek:
The noise should be very small and I don't even notice it any more when using relay-switched pedals.
More reading material: http://www.muzique.com/lab/pop.htm
Best regards, Jack
Here's 2 related links to a great article on the very best Relay Driver alternative to the MCU. Should solve all your non MCU relay woes -
https://www.freestompboxes.org/viewtopic.php?f=13&t=13295&p=278062&hilit=mictester#p278062
https://www.diystompboxes.com/smfforum/index.php?topic=118021.msg1097598#msg1097598
Cheers, Trevor