Relay true bypass power Consumption

[anotherjim]

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 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.

[Rob Strand]

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

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:

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.

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.

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?

Definitely,  no point messing with the relay circuit.   The exact mechanism causing it isn't clear as there can be many causes.

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.

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.

[amptramp]

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.

[jackwithoneye]

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

Make sure you have the resistor (R26) and cap (C15) at the input of your circuit as mentioned before in this post:

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.

done

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

[antonis]

It just started from a humble power consumption query..

[jackwithoneye]

It just started from a humble power consumption query..

Well, that escalated quickly 

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:

[Rob Strand]

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
...
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.

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.

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.

[Rob Strand]

The 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).

[jackwithoneye]

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)

The 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?

[amz-fx]

- 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. 

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

[bluelagoon]

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