3 effects in 1 switching

[Serge]

I've seen several posts dealing with "switching between several effects in one enclosure", but I can't really find what I'm looking for... I would like to switch between 3 effects in one enclosure and want to avoid that I need to turn off one effect before turning on the other.  This means that when e.g. I would turn on effect 2, automatically effect 1 would be turned off.  Does anyone have any specific suggestions on how I can do this?

[The Tone God]

You are now entering the world of logic controlled switching so you might to look at some basic digital gate logic material.

Andrew

[Mark Hammer]

Switching between 2 effects in one box is dead easy and only involves a second stompswitch.  Step on it once and effect A is on with effect B out of circuit.  Step again, and you swap.

Switching between three effects, though, can kick the requirements up a notch.  My guess is that unless you are willing to use a toggle or something to select between two of them, and then use a stompswitch to select between the first pair or the 3rd effect, the switching will:

a) move from purely mechanical and true bypass (read: "Easy to do" not "better) to electronic, and
b) requiring some sort of logic where if A goes high, B and C go low, if B goes high, A and C go low.

It's quite feasible to do, but the added logic circuit would up the size of the board and perhaps impose too much circuitry in too little a box.

It would be nice if there was something like those old car radio switches, where pressing any button cancelled all the other buttons.  While you can certainly buy those button assemblies in surplus places, they're not for foot operation.

[Ben N]

Would this help?

http://hammer.ampage.org/files/quadsequentialswitch.pdf

I vaguely recall someone posting something simpler, using a CMOS chip to select any one of, I think, up to 11 (?) FX choices by controlling a series of CD4053 bypass circuits or relays, a la Geofex, and turning all the non-selected ones off, but now I can't find it.

Mark? RG?

Edit: Wait! Here it is: http://www.geofex.com/Article_Folders/fxswitchr/fxswitchr.htm. Not the whole project, just the use of the Octal latching switch. That would do what you want, methinks.

Ben

[R.G.]

Ben beat me to it. Methinks he's right.

The transparent latch trick with CMOS works GREAT!! It automagically gives you one-of-N latching. You can use the 74C373 for anything up to 8 switches and I think I could get this to work with two chips at a time.

[RaceDriver205]

Well Im going to post this for the third time. No one has been willing to find out if it works or not (or taken any interest in it for that matter).
Multi-fx switcher using only 3PDT relays and SPDT footswitches:

[Meanderthal]

 That's pretty interesting! The only thing that would bug me would be having to turn the top switch off to get the others on, etc... , but if ya started with the bottom switch on, switching either of the other 2 on would turn it off. 

[RaceDriver205]

The switches are momentary (push buttons).
As I recall (I drawed the circuit a while ago) it relys on the switch 'grey area' (neither on or off) being shorter than the time required for the relay to de-energize.

[Serge]

Thanks for the input so far.  The trick with the CMOS does look sexy to me   To me it seems much more practical than those bypass strips.  I wonder why there isn't more interest in this thing?  As far as I can see, RG came up with this in 2000 and there haven't been a lot of posts on this thing.  It looks great though...

[sfr]

Once you get your bypass working with with logic like the CD4053, you can do all *sorts* of neat things, because bypassing a pedal is simply a matter of sending a high or low voltage to specific point - simply by switching what pedals are attached to what latching circuitry, you can do all sorts of neat things.  I look forward to implementing it in my multi-fx unit(s), ideally to allow me to switch multiple, non-consequtive FX on and off with one switch, implement the option of momentary switching without adding an extra footswitch, and the like. 

I'm *very* interested.  I've been dreaming of fancy electronic switching for some time.  I finally began to tackle it a few months ago.  Unfortunetly, I ran into some problems with my layout based on the CD4053 based switching over at Geofex (which I'm sure are my fault).  I've been meaning to go over it again and get it working, I've just been too busy with other projects as of late.

[RaceDriver205]

Argh! My circuit has been ignored again
Nooooooooooooooooooo!

[Barcode80]

not ingored, i believe meanderthal posted on it just then. i think the reason more people haven't tried yours is the parts count/cost. a cmos chip is much cheaper than 3 spdt switches and 3 3pdt relays.

[Mark Hammer]

Not just parts cost or layout, but current requirements too.  Even highly efficient relays are not the sort of thing you could ever hope to run off a 9v battery for very long.  Doesn't make it a bad idea, just something that a great many people here simply file away for "when I do something that's only AC-powered".

[R.G.]

Argh! My circuit has been ignored again Angry
Nooooooooooooooooooo!

Well, I'd hate for that to happen.

Well Im going to post this for the third time. No one has been willing to find out if it works or not (or taken any interest in it for that matter).

I say this in all amity - no one is going to care whether your ideas work as much as you do. I've always had to go try my ideas out on my own.

That being said, there is some reason to believe it would work. I'd try it for you, but I don't have four 3PDT relays handy for that.

There is another circuit with relays that I have seen demonstrated. It relies on the fact that when coil current falls below some value a relay will drop out.

You take a relay and measure its hold current. I guess you need to measure the relays you'll be using and get the worst case of the several you'll use, actually. Then calculate the resistor you'll need to let just a bit more than the maximum hold current for your relays through with a diode in series with the coils, one diode per relay, and one pole of the relay to latch the hold current if the relay is activated.

Hook up to your power supply this one resistor, and a diode in series with each coil. Also hook up  one normally-open pushbutton switch per relay from your power supply voltage directly to the coil, around the resistor and diode.

What happens when you turn on the voltage is - nothing. No  relay is energized, and all relay latching contacts are open. When you press one pushbutton, the switch lets full voltage through to the relay coil and that relay comes on, it's latching contact connects the coil to the hold-current relay through its diode, and so the relay stays latched when you release the pushbutton.

When you press another pushbutton, that relay is forced on through its switch. Its latching contact hooks it up to the holding current, and both the previously activated relay and the new one are connected to the hold current. Half a hold current won't hold in either one, so the previous relay drops out, leaving the new one connected to the hold current. The new one then stays latched when its pushbutton opens.

It's a little fiddly setting up the relays and resistor values, but I've seen this one work.

[RaceDriver205]

I say this in all amity - no one is going to care whether your ideas work as much as you do.

Yeah, I know. I just thought that on each occasion I posted it it was perfect for what was asked for. I mean, no hard feelings or anything!

[Serge]

RaceDriver205 - I haven't ignored you.  Sorry if I gave that impression.  I'm actually willing to give your suggestion a try, if only I can find the appropriate relays...