Remote FX switching

[DLR Guitarist]

I've been toying around with the idea of building a remote FX switching unit.  I've read the articles at Geofex, and they seem kind of complicated.  I was wondering if a simple solid state relay (DPDT) could be used instead of complicated circuitry.  I was thinking about having the relaxed state be the FX pass, and the switched state be the FX in the loop.  That way, I could simply apply a voltage to the relay by a remote DPDT latching footswitch.  I don't really care about having an LED lit up on the FX part, and it would be easy to wire an LED on the remote control. 

[d95err]

A mechanical relay would work of course (that's how switchers like Lehle do it).

I'm interested too about solid state relays - does anyone have any experience with those? I'm thinking that SS relays should require less power and therefore be easier to run quiet without hum or clicks.

[R.G.]

There are reasons that the commercial stuff doesn't use solid state relays. It has to do with the ways in which all switches are non-ideal.

Mechanical switches are good from the signal switching standpoint. They are very low resistance when on, very high resistance when off. But they are big, heavy, complicated to use, expensive and they have extraneous noise and bounce. However, they are the professional choice because they don't degrade the signal.

Modern solid state relays keep getting better, but in terms of signal quality, they are still not as good as mechanical switches or CMOS switches. They are not as "off" when they're off, and when they're "on" they have signal distortion issues. Or the good ones are too expensive by the time you get through with cobbling up enough of them to fake a relay.

Besides - if SS relays were as good or better, didn't you think there would be info at GEO about them?   

[Mark Hammer]

If you have any commercial pedals that use FET switching, you can switch these remotely simply by sinking a small hole in the box, installing a mini (1/8") phone jack, and running a cable from there to a second remote switch that parallels the onboard momentary.  This has been discussed here frequently so perhaps a search would deliver up all the needed particulars.

And since we're both on at the moment, "hey" there in Texas.

[R.G.]

Y que tal, amigo?

I have a fencing company putting up fence right now. It's doubled my Spanish in a couple of days.

'Course, getting from two words to four is easy.   

[DLR Guitarist]

Thanks for everyones help.  I found another method of switching at Geo. 

http://www.geofex.com/Article_Folders/cd4053/cd4053.htm

I'm not sure how I missed it before, but I was able to find 7 CD4053 ICs on ebay for $4 including shipping.  So, I'm going to give that a try.

As for using the FET switching already in the pedals, I thought about that too, but there are pedals that I want to take out of the signal chain due to added noise, even when they're in the OFF state.

[Arfman]

Thanks for everyones help.  I found another method of switching at Geo. 

http://www.geofex.com/Article_Folders/cd4053/cd4053.htm

I'm not sure how I missed it before, but I was able to find 7 CD4053 ICs on ebay for $4 including shipping.  So, I'm going to give that a try.

As for using the FET switching already in the pedals, I thought about that too, but there are pedals that I want to take out of the signal chain due to added noise, even when they're in the OFF state.

Doing this very thing is high on my wish list. I want to get the pedals off the floor, have everything true bypass and overall shorten the entire length of the signal chain. I thought the remote footswitch board article on geo is great. I think I figured out a simple way to add program switches and I'm just wrestling with how to make sure everything gets to the correct state when I push a program button that is to turn multiple, selected pedals on. Right now I'm narrowing in on a circuit that would send out a pulse to the bypass all and then a delayed pulse via a LM555 timer to the selected program. It's looking good in Spice...see how it does in real life. I learned a long time ago in using Spice for these type of switching circuits to simulate a very bouncy mechanical switch...

Anyway, good luck and hope to see more posts on this...

[DLR Guitarist]

Would it be safe to power 5 or 6 CD4053 chips with a singld power source designed for a 9V pedal (9V, 200 ma), or should there be more???

[DLR Guitarist]

Also, I found an alternate scematic, which looks a little simpler, includes an LED display for the FX switching box, and has a schematic.  Does anyone see any problems with this switching method?

[R.G.]

Would it be safe to power 5 or 6 CD4053 chips with a singld power source designed for a 9V pedal (9V, 200 ma),

That's fine.
A

lso, I found an alternate scematic, which looks a little simpler, includes an LED display for the FX switching box, and has a schematic.  Does anyone see any problems with this switching method?

Maybe there's a reason it's simpler. 

Actually, if you read my article on switching with the CD4053 at GEO you already know the answer. The reason the GEO circuits are more complicated is that they bias the inputs at near the middle of the DC supply for the CD4053. Doing this suppresses clicking in the 4053 to a very great degree.

Finally, Laurier's circuits sometimes tend to be... um... less well thought out and tested sometimes from comments I've heard. I have not built this specific one.

[DLR Guitarist]

Thanks.  I was assuming that the Geo version was better, but I wasn't sure if the other diagram had been biased in another fashion.  Thanks.

[DLR Guitarist]

Sorry if I'm starting to bug anyone yet with the questions, but I have another one. 



in this diagram, there is a 1M resistor to ground before the capacitor.  Is this filtering, or does it serve another function?

[R.G.]

No, it's not for filtering. It's a pull-down resistor to pull the outside ends of the in/out caps to ground.

You might save yourself the next seventeen questions by reading the rest of the articles at GEO. They're probably in there.

[David]

Also, I found an alternate scematic, which looks a little simpler, includes an LED display for the FX switching box, and has a schematic.  Does anyone see any problems with this switching method?

DLR:

DON'T WASTE YOUR TIME ON THIS ONE!  Trust me, I already tried it.  No go, dude!

[DLR Guitarist]

Thanks for the warning.  I'm going to use RGs method.

[David]

Thanks for the warning.  I'm going to use RGs method.

Good plan.  You'll save yourself a lot of grief that way.