I read about relays and I'm more confused now then ever

[mth5044]

Seriously. After reading R.G.'s article about them, and searching around on the forum, I'm even more confused then ever.

I thought maybe learning about them would help with an idea I had. I've gotten into putting effects into other enclosures with toggle switches and putting them ontop of my amp. This worked out for a while, but the two problems I started having were 1) It's so much easier to stomp it off while playing (obviously, so dont go saying just put stomp switches and put them on the floor  ) and 2) some amps are too low to just reach over and flick it off. So I started looking into relays to put some stomp switches on the floor for the effects, kind of like rack units.

I figured it wouldn't be too hard of an endevor, just a 'relay' and a momentary switch. But after reading that, I don't know wtf to do.

Most of the effects are only on/off, which I may be able to figure out, but the other one has three different options that I wanted to put switches on the floor for.

I guess I can go into more depth, but first I have to ask if this is going to be simple enough for me to read about and do or am I going to have to get one of you helpful folks to give me some hints?

So what other readings are there that may get me on the right track? Like 'relay switching for beginners' or something along those lines.

Thanks 

[frank_p]

In the first case:
The relays are a bit like a dpdt switch, you wire them just like if it was a carlington stompswith; except for the two leads of the electromagnet.  In this situation you have to give the electromagnet a way to stay on or stay off once you touched a NO or NC switch.  Now that is proabably the difficult part : you have to do a circuit for that.

In the second:
you don't need a relay: just send the switch to the box on the floor and have one on the stompbox that is sitting on the top of your amplifier.  Wire the two of them in parallel.

Check also the electronic papers on The Tone God site, it could give you some hints:
http://www.geocities.com/thetonegod/switches/switches.html

[mth5044]

Thanks for the link. But wiring one switch in parallel with the other... wouldnt that mean running the signal all the way down to the floor through a chord.. and somehow connect it to a 3PDT switch in the ground? Wouldn't that make for some awful tone degredation?

[R.G.]

Seriously. After reading R.G.'s article about them, and searching around on the forum, I'm even more confused then ever.

I thought maybe learning about them would help with an idea I had. I've gotten into putting effects into other enclosures with toggle switches and putting them ontop of my amp. This worked out for a while, but the two problems I started having were 1) It's so much easier to stomp it off while playing (obviously, so dont go saying just put stomp switches and put them on the floor  ) and 2) some amps are too low to just reach over and flick it off. So I started looking into relays to put some stomp switches on the floor for the effects, kind of like rack units.

I figured it wouldn't be too hard of an endevor, just a 'relay' and a momentary switch. But after reading that, I don't know wtf to do.

Most of the effects are only on/off, which I may be able to figure out, but the other one has three different options that I wanted to put switches on the floor for.

I guess I can go into more depth, but first I have to ask if this is going to be simple enough for me to read about and do or am I going to have to get one of you helpful folks to give me some hints?

So what other readings are there that may get me on the right track? Like 'relay switching for beginners' or something along those lines.

I thought what I wrote WAS "relay switching for beginners." 

Let's see if we can straighten this out.
1. Switches come in two flavors - alternate action and momentary. Momentary switches stay switched only as long as you're holding them switched with your hand/foot/whatever. Alternate action switches stay where you push them, and you have to do something to them to make them switch back. For switches YOU are the actuator. Your pushing/pulling/etc. muscle power moves the contacts. It's a property of the kind of switch whether it stays where you put it or springs back when you let go.
2. Relays are switches where you have substituted an electromagnet for your muscle power in moving the switch contacts. The most common relays are momentary switches, so you have to keep the electricity flowing in the coil to keep them pulled one way. They 'relax' to the other way when you let the electricity quit flowing.
3. A very, very few relays are the equivalent of alternate action switches. That is, you can pulse the electricity into the relay coil and this moves the switch. Once it's moved, you can just stop the electricity and it will stay where it is. You then need to use electricity the other direction to move it back, just like you have to flip a toggle switch back. These are called latching relays.

It takes more than just a relay and a momentary switch to do what you want. If you have the normal kind of relays (that is, not "latching") then you have to make some kind of electronic memory to hold the relay where you put it. Your momentary switch tells the electronic memory "change now!" and it flips, changing the setting of the relay. If you have a latching relay, you can use a momentary switch to cause the relay to flip to a new state, but you still have to have some cleverness in the electronics to tell the relay which way to flip from where it is.

Let's stop there and take stock. Then we can go on.  Did that make sense to you? Where is more explanation needed so far?

[frank_p]

I am surely going to come back then, since I am working on it also, and I am not an expert.

[mth5044]

RG - Haha yes, somehow that made a lot of sense. I am well aware of the kinds of switches, but for some reason I just wan't getting the relay part of what I was reading (which was basically the whole thing), but you explaination makes a lot of sense.

After reading the link from Frank_p, I think it is probably going to be easier for me to use the Tone God's Wicked Switching doodad. I'm going with the momentary inverter switching with a 40106 and a 4066 IC. The layout looks pretty easy to follow.. a momentary footswitch, two IC's, three resistors and a cap. Not sure why this isn't used by more people... it seems to be cheaper then a $10 3PDT switch. I guess the whole "true bypass" thing sticks with a lot of people.

Thanks for your explaination RG. Even though I'm not using it, it's good to know stuff.

I'm sure ill be making a thread with questions about that in about 5 minutes  Unless I should just post them here... you guys have any experience with the wicked switch?

[mth5044]

Yah know.. the more I think about it.. the more I cant figure out how amps and stuff use 1/4 in plugs for these multibutton switching system? Don't they use something similar to the wicked switch? How am I going to get 3 momentary switches in one enclosure connected back to the effect ontop of my amp?

Sorry if this thread has turned into more of a 'spill my ideas and hope for sollutions' thread. I made so many threads today, I would feel bad for making another for such things.

Thanks for any info.

[frank_p]

It's getting late for this but I think I am going back to it next week. OkaY ?

[cheezit]

I've considered trying something along these lines going back quite a few years.  The issue has always been finding a relay that is
- not incredibly noisy (mechanically) - a giant "clack" from the relay is really annoying unless you are playing loud
- has the right switching characteristics (make before break, that sort of thing)
- cost-effective

Others have been very concerned about current draw, but I don't think that is important if you are trying to get the switching away from the 9v-power domain of floorboards.

R.G., have you found any specific relays that are particularly suited to this type of signal switching?

[R.G.]

Actually, if you read the rest of GEO, there are several articles about how to do remote switching with relays and CMOS switches too. Try reading these:

A Remote Footswitch Bypass System -http://www.geofex.com/Article_Folders/pffootsw.pdf and http://www.geofex.com/Article_Folders/remoteftsw.pdf
Remote Relay Switching - http://www.geofex.com/FX_images/relays2.gif
Electronic Switching with the CD4053 - http://www.geofex.com/Article_Folders/cd4053/cd4053.htm
A Programmable FX Switching System - http://www.geofex.com/Article_Folders/fxswitchr/fxswitchr.htm

This last one has the trick for making a momentary switch latch one-of-N switches in it, down at Figure 7. That's the key to a programmable setup done electronically. If you just want to remote switch each effect, not batches of effects, the first link shows how to use CMOS to get the alternate action from a momentary switch and then how to use an alternate action switch as a momentary switch. 

[cheezit]

I've considered trying something along these lines going back quite a few years.  The issue has always been finding a relay that is
- not incredibly noisy (mechanically) - a giant "clack" from the relay is really annoying unless you are playing loud
- has the right switching characteristics (make before break, that sort of thing)
- cost-effective

Others have been very concerned about current draw, but I don't think that is important if you are trying to get the switching away from the 9v-power domain of floorboards.

R.G., have you found any specific relays that are particularly suited to this type of signal switching?

I dug out an old Peavey Rockmaster rack preamp that has a bunch of relays for channel and effects switching, and they work well, no pops and the mechanical noise is not objectionable.   The part that is used there an Aromat DS2YE-S-12V, which is a 12V signal relay.   Mouser cross-references that with the $2.80 Fujitsu RY-12W-K---datasheet here:
http://www.fcai.fujitsu.com/pdf/ry.pdf

There are 18V and 5V versions of similar relays---5V would be best for interacting with logic circuits but there are fewer choices (such as the Fujitsu RA series).  But I think it would probably be necessary to build to a control voltage (such as 5v) and then try as many different relays as needed to find a good part.  The pinouts do seem to be similar for many of these parts.

[R.G.]

Yes, the relay business is highly competitive, and there are many sources for the commoner small relays.

My personal favorite is the NEC-made EA2 series, but Fujitsu, Omron, and many manufacturers make small DPDT relays that will fit the same footprint and hole pattern. They also make latching relays which fit the same patterns as well.

Relays come in standardized voltages: 5, 6, 9, 12, 18, 24, sometimes 48. Obviously, the 9V is what we would want, but those tend to be special order only, as a 9V battery will not last long powering a relay coil, and so makers of battery powered anything tend not to use relays. For the small relays like the EA2, a 9V coil is about 600 - 800 ohms resistance, so the current is about 15ma or more, like adding a second LED. So the manufacturers don't make it as a standard item. People who order relays in quantity order them in 5V (for driving by logic) or 12V (for driving from a transistor). Those are what the distributors stock.

Latching relays work great in pedals, even from batteries, because it only takes a pulse of current to set or reset them; however, you have to make a more or less complicated circuit to apply the pulse. Most people who read here can barely just cope with wiring an effect and a bypass switch, so having to make yet another circuit for the relay puts it out of reach.

[mth5044]

Thanks for all those links, I added them to my favorites for reference. You sure put a lot of work into that stuff, looks good  

But for me, it seems like an awful lot of work compared to the 'wicked switch'. Especially for only one external switch. But for the three switches, relays may seem more appropriate, like the other effect I am planning. I'm trying to sort out the pros and cons between the two switching systems for a 3 switch set up, and so far I have come up with this

Wicked switch

Pros - simple, low part count, I can mostly understand it, very small pcb or perf layout, cheap parts
Cons - how to get six wires out of the back of the effect and into the switchs on the ground

Relay

Pros - Easy way of connecting the bunch of wires from switches to effect
Cons - Large circuit board needed to make it, large part count, price of relays, complicated

I guess to solve the wicked switch problem, I could use one of them DB15 cables that you show in the 7. Footswitch logic. I'm trying to find away around that because I won't be drilling these enclosures, so I can't make that kind of shape.

That's all I got right now, I'm working on a perfboard version of the wicked switch with 4066 and 40106, seeing as I can't make PCB's either  

Thanks for everything so far, I look forward to anything else you got!

[mth5044]

Latching relays work great in pedals, even from batteries, because it only takes a pulse of current to set or reset them; however, you have to make a more or less complicated circuit to apply the pulse. Most people who read here can barely just cope with wiring an effect and a bypass switch, so having to make yet another circuit for the relay puts it out of reach.

Haha, well I can wire a bypass switch easily, but besides that, you are correct.

[cheezit]

So I had a thought---replacing the ubiquitous 3PDT stomp switch inside the pedal with:
- a cheaper/easier-to-source/more reliable SPST footswitch
- a 5v non-latching signal relay
- a current limiting resistor in line with the coil
- wiring the LED in line with the coil
- one end of the coil is powered, and the SPST switch grounds the other end when engaged.

This is really not much more effort or expense than the standard "blue switch" approach.  But it allows for something really cool: by simply patching in a jack, the pedal can be remote-activated. 
- the jack could be a NC/shorting type 1/8" mono jack; when a plug is present the SPST switch on the pedal is disabled, and grounding the tip to the sleeve now enables the pedal.  Run a long 2-conductor line to an SPST switch in line with an LED, and you have an instant remote footswitch.
- if this were done to all the pedals in a rig, all the relay-switching could be done at the pedals on top the amp and a set of control lines run down to a bank of SPST+LED pairs housed in a long strip.
- the lines to the strip can be replaced with a multiconductor line for a neater appearance/less stage mess.  No audio travels over these lines, but shielding is probably a good idea since higher-gain pedals may pick up noise through the power supply.  Wiring up the connectors would be a pain but standard connectors (RS-232 etc) for computers would probably work.  You just need a separate conductor for each effect.
- the strip can be replaced with something more complex that allows for sets of pedals to be defined (perhaps via DIP switches with 'vegomatic' control circuitry) and switched between.
- for the really ambitious, a MIDI interface that controls the pedals remotely using program changes would be possible.  This is like some of the commercial effects switchers.
- the pedal behaves "normally" if the control plug is removed from the jack.
- for vintage/commercial effects, this stuff can be housed in a discrete "loop" box and controlled in the same way.  Instant true-bypass.

This probably forces the pedals to be adapter-powered since most relays will eat the battery.  Then again, the relay takes up room, so there might not be space for the battery once this is done.

This is strictly a thought experiment at this point and very likely others have thought of it/tried it, and perhaps there's a fatal flaw... but I do think the idea of keeping the relay switching separate from the control logic generates a lot of interesting possibilities.

[R.G.]

I should have noted that there was no offense intended when I said that. In many ways, spending your time practicing and playing is a better choice than spending your time building pedals. I'd have done that if I had any talent as a guitarist.

There is no reason that anyone *should* be capable of more than that unless they have had some training.

@cheezit:
You're getting there. That's part of the line of thinking that led me to do the articles on remote footswitching at GEO. Here are some pointers:
- use 5V relays so there is some voltage left over for the typically 2V LED drop.
- You may need to stick in a JFET current limiter (gate tied to source) to keep things in bounds when the voltage is 9 or 9.5 instead of 7, as it is with a weak battery. If you will never use batteries, you can just put a resistor in series with the coil and LED to soak up the extra couple of volts.
- You get into problems when you want an LED out at the footswitch where you can see it AND back at the box with the effects. You run out of volts, even with a 5V relay. One way to do that is to have the footswitch have just an LED and resistor in series with it and have the circuits back at the box have a transistor which turns on the relay and another LED in the box when the footswitch is active.
- This last lends itself well to choosing groups of pedals
- For the whole nine yards of choosing groups of pedals remotely, read the remote programmable footswitch article and the ASMOP articles.
- Also read the "steel studs" articles for suggestions on where to get the materials for housing the footswitches and switching circuits.

[mth5044]

Welp, after most of the day surfing the internet and looking at relays and switching, I think I'm just going to go with the wicked switch, but connect it with three 1/8 cords running between the switch on the floor and the effect on the top of the amp. A few wire ties can clean it up i guess and the 1/8 cable can be cheap as it isn't actually carring a sound signal (I think....). It wont be the prettiest thing, but I cant find any circular jack/connectors with six or more ports to send the to and from signal for each switch.

Thanks for your helps. I favorited all the relay info and I hope to look into it some more later, but it's beyond me right now. Thanks a lot!

[kurtlives]

Seriously. After reading R.G.'s article about them, and searching around on the forum, I'm even more confused then ever.

I thought maybe learning about them would help with an idea I had. I've gotten into putting effects into other enclosures with toggle switches and putting them ontop of my amp. This worked out for a while, but the two problems I started having were 1) It's so much easier to stomp it off while playing (obviously, so dont go saying just put stomp switches and put them on the floor  ) and 2) some amps are too low to just reach over and flick it off. So I started looking into relays to put some stomp switches on the floor for the effects, kind of like rack units.

I figured it wouldn't be too hard of an endevor, just a 'relay' and a momentary switch. But after reading that, I don't know wtf to do.

Most of the effects are only on/off, which I may be able to figure out, but the other one has three different options that I wanted to put switches on the floor for.

I guess I can go into more depth, but first I have to ask if this is going to be simple enough for me to read about and do or am I going to have to get one of you helpful folks to give me some hints?

So what other readings are there that may get me on the right track? Like 'relay switching for beginners' or something along those lines.

I thought what I wrote WAS "relay switching for beginners." 

Let's see if we can straighten this out.
1. Switches come in two flavors - alternate action and momentary. Momentary switches stay switched only as long as you're holding them switched with your hand/foot/whatever. Alternate action switches stay where you push them, and you have to do something to them to make them switch back. For switches YOU are the actuator. Your pushing/pulling/etc. muscle power moves the contacts. It's a property of the kind of switch whether it stays where you put it or springs back when you let go.
2. Relays are switches where you have substituted an electromagnet for your muscle power in moving the switch contacts. The most common relays are momentary switches, so you have to keep the electricity flowing in the coil to keep them pulled one way. They 'relax' to the other way when you let the electricity quit flowing.
3. A very, very few relays are the equivalent of alternate action switches. That is, you can pulse the electricity into the relay coil and this moves the switch. Once it's moved, you can just stop the electricity and it will stay where it is. You then need to use electricity the other direction to move it back, just like you have to flip a toggle switch back. These are called latching relays.

It takes more than just a relay and a momentary switch to do what you want. If you have the normal kind of relays (that is, not "latching") then you have to make some kind of electronic memory to hold the relay where you put it. Your momentary switch tells the electronic memory "change now!" and it flips, changing the setting of the relay. If you have a latching relay, you can use a momentary switch to cause the relay to flip to a new state, but you still have to have some cleverness in the electronics to tell the relay which way to flip from where it is.

Let's stop there and take stock. Then we can go on.  Did that make sense to you? Where is more explanation needed so far?

RG why not use a normal latching SPST footswitch to break or make the connection for the relay's coil? That way you could hit the switch once and the non-latching relay would stay in one position.

[R.G.]

RG why not use a normal latching SPST footswitch to break or make the connection for the relay's coil? That way you could hit the switch once and the non-latching relay would stay in one position.

That works of course. In that case, the latching SPST footswitch is being the "memory" for the relay. I thought the article covered that. Anything you do which tells the relay "Be on now..." and holds that until you want it off, and can supply the needed current and voltage works fine. An alternate-action mechanical switch (which is the same thing as a mechanical flipflop!) works fine. A logic flipflop work. You can even make RELAY flipflops to do it.

The only really, really nice thing about using a separate flipflop from the activating switch is that if you want two or more switches to activate the relay from different places, a flipflop plus relay will do that seamlessly. Otherwise, you're always worried about the state of the other switch when you flip this here local one to make the relay change. It gets really complicated. Not impossible, but complicated. My favorite is CMOS logic to do the logical functions because they operate cleanly and clearly (or, as Spock would say, logically) and when the logic AND/OR/XOR/ETC is done, the result is a simple on/off signal to put to the relay.

But if what you want is ONE remote footswitch and NO local activator switches in the unit itself, then yes, a remote alternate action stomp switch works fine.