1-At-A-Time 3 pedal switcher

[aviherman5]

Hi all!

I'm building a preamp pedal with a 5150, SuperLead, and Brownface in it, but for obvious reasons, I don't want two to be on at once.

I plan to use soft switches and relays to make this happen, but I have no idea how to ANALOGLY make it so that one turns on, the rest turn off. I'd also like the ability to have none on at all.

Is there any way to do this with logic gates driving a transistor driving a relay, or do I need to code this?

Thanks!

[Kevin Mitchell]

I don't want two to be on at once.

Signal or power wise?
You can definitely use logic switching for the signal - no relay needed.
You'll need something to act as a DP3T. A pair of CD4051 chips can do this for ya! - One for input, one for output.
You may also also want a latch for the button switch, such as a CD4013.

Edit: I actually found a better chip after looking at the datasheet. CD4052 can act as an analog 2P4T switch. Perfect!

Was going to draw a sim but nervermind.
You can use R.G.'s CD4053 bypass as a guide if you need help understanding how these work.
http://www.geofex.com/article_folders/cd4053/cd4053.htm

Just keep in mind the CD4052 uses 2-bit binary to determine the switch position. The easiest thing to do is to use a click counter IC. Though a 2-bit click counter circuit is rather simple - especially with other logic ICs.

[Mark Hammer]

Another approach is to use a "sequential" switching arrangement.  That is, a single momentary switch steps across however many options you have, in round-robin fashion.

http://www.muzines.co.uk/articles/build-a-quad-sequential-switch/5287

[ElectricDruid]

Further to what Kevin said, since the 4013 is a dual flip-flop, it's ideal to use as a two bit counter.

So a 4013 and a 4052 and you're there!

[Kevin Mitchell]

Further to what Kevin said, since the 4013 is a dual flip-flop, it's ideal to use as a two bit counter.

So a 4013 and a 4052 and you're there!

Indeed using two channels of a 4013 in series will act as a 2-bit counter! However, you'll need something extra for it to reset after position 3. Also something to light 3 LEDs sequentially if desired - such as a nor gate when byte 00 is set. Or even a CD4051 which would also use the same counter bits - just drive the LEDs with transistors.

[Kevin Mitchell]

You could try this if you want to go the 4052 route. Like I had suggested above, a CD4051 would be ideal for LED indicators but you could also use the 4th position to trigger the latch's reset - keeping it bound to 3-throws only!
The two D-type latches are a single 4013 and the demultiplexer would be a CD4051. No sim for the CD4052 but it's rather trivial to include.

[ElectricDruid]

Indeed using two channels of a 4013 in series will act as a 2-bit counter! However, you'll need something extra for it to reset after position 3. Also something to light 3 LEDs sequentially if desired - such as a nor gate when byte 00 is set. Or even a CD4051 which would also use the same counter bits - just drive the LEDs with transistors.

Honestly, my solution to that would be to think of something to do with the fourth position! Either wire it straight through so there's a "preamp bypass" position as well, or think of something else to stick in there (simple buffer? treble booster).

It's a lazy solution I know, but it's the weekend already!

[aviherman5]

Thanks for all the suggestions! Will process and get back!

[PRR]

... wire it straight through...

+1

[Processaurus]

Another approach is to use a "sequential" switching arrangement.  That is, a single momentary switch steps across however many options you have, in round-robin fashion.

http://www.muzines.co.uk/articles/build-a-quad-sequential-switch/5287

I had the Sansamp Tri-OD that was a 3 channel thing, or 2 channels and bypass, done sequentially with one footswitch, and trying to use it onstage cured me of ever wanting to do a sequential switch on any homemade pedals- it sounds simple but it was easy to overshoot the desired setting or otherwise mess up while trying to do everything else in a performance. It was a little puzzle every time you wanted to turn your distortion off and on.

Only way I could see it working for live use is if there was a bypass switch, and then the sequential switch you could mess with in between songs.  The version they made after it, the Tri-AC had 3 footswitches for the 3 channels and was sooo much easier to operate.