Switching between pots

[Clayford]

Is there practical way to have 2 gain and 2 volumes on the Chunk Chunk? Accessible by a single foot switch? Think channel 1 and channel 2. Yeah it'd be the same tone, but you could setup a crunch preset and then a distortion one. I know I've seen switchable Gain and switchable volume on different pedals. I know you can switch and indicate a single pot swap thanks to Dano over at Bevisaudio. I know that we can go with 3 3pdt switches - Effect On/Off Gain1/2 MVol1/2, all indicated. My box for the Chunk could handle that and that might be more useful.

But now my curious mind wants to know, can you rig a single switch that swapped between the 2 sets (2 V 2 G) and had an indicator? It seems you need a 3pdt to get a pot and an LED - So a 4pdt could swap 2 sets of pots but give no indication (unless there's a way?)
 

[Matt]

The only thing I can think of that might possibly work would be to wire a pot as a resistor and connect it between lug 3 of the gain pot and where lug 3 attaches to the pcb.  You would then make that switchable.   But that will only give you an option to lower the amount of gain.  Again, that's if it works.

[jkokura]

With Relays you can do it. In many relay based systems you can put several DPDT relays in parallel, so putting multiple switches on a single stomp is possible. That's probably the most efficient. I don't know that there are any 5PDT stomp switches.

Jacob

[Clayford]

With Relays you can do it. In many relay based systems you can put several DPDT relays in parallel, so putting multiple switches on a single stomp is possible. That's probably the most efficient. I don't know that there are any 5PDT stomp switches.

Jacob

I figured it would involve a relay solution - could it be done with 4 of these and a DPDT stomp? I think I'd rig it up on pad per or vero and use the switch to add or remove the voltage? I'm guessing here - I've never done much with a relay other than building a replacement stomp switch for my Amp - which was either open (clean) or closed (lead). I didn't do squat for that other than solder the switch and the RGB led up(power comes from pedal board).

This could be worth looking into further as I'd like a stomp solution for my wiener wah for the boost rather than a toggle switch

[jkokura]

You need a way to throw the switch. There are ICs and transistors you can use, but essentially many relays work like this:

- Apply a voltage to the relay's coil, the switch flips
- Apply a voltage to the relay's coil, the switch flips.

Some of them work like this:

- Apply a voltage of XV to the relay's coil, the switch flips
- Remove the voltage of XV to the relay's coil, the switch flips.

The key with relays is to solve the debouncing problem, and to make sure you keep the size and cost down. Bouncing is where the switch flips back to the previous state, instead of staying in the state you want it to.

What I suggest is that you look at some commercially available relay driven elements, or perhaps some of the DIY options, like the wicked switch. Designing from scratch yourself will take some work and prototyping, and while you may be willing to do that, there are options out there you might be able to consider using already.

Jacob

[Govmnt_Lacky]

Haven't checked the circuit before posting this but....

If the Gain control is set up as a variable resistor (and NOT a voltage divider) like the Volume control pot, then you could accomplish it with a 4PDT. The downside is that you wouldn't be able to have an LED indicator though   

[Clayford]

I'll look into TTG's wicked switch -

I think for now I'll setup my Chunk Chunk for 3 switches -
1 Effect/Bypass -
1 - Vol1/2
1 - Gain1/2
I don't grok voltage divider... It looks like it's working similar to the volume which I think is a variable resistor. Now it comes to figuring out if I need a 4pdt or 3pdt for the Gain. It does appear that pin1 for both are part of the ground plane - and 2 and 3 are in the circuit are acting as a variable resistor. If I'm wrong - please educate! I have no real EE background.

[RobA]

Volume pots are variable voltage dividers.

You would need to use a latching relay. Check out this schematic from Geofex.


That's a double latching relay used as a bypass. You could adapt it. I had to take the plus side of the relays to +V as well. I think there is a missing connection on the diagram.

The hex inverters will do your debouncing and condition the momentary switch to trigger the latching relay.

Those Tayda relays are non-latching (at least the ones I got from them were) and you have to apply voltage to them to keep them flipped. Not ideal for a pedal.

[Clayford]

So when I'm ordering parts for the pedal - will I be able to get by with 3 3pdt's or will I need 1/2 4pdt switches since I'm going to go with 3 individual switches for what I'm wanting to accomplish. The selectable vol and gain individually will actually give more options.

[jkokura]

Honestly, you don't need to do two different switches. Getting different gain settings is usually enough.

If I were you, I'd be looking at getting a Chunk going with 2 different gain settings, then running a boost after it to get a louder volume. The only reason to change the volume on the Chunk is to get a lead boost, and you get one and have more flexibility by running a LPB or SHO behind it or something like that.

Jacob

[Clayford]

There you go thinking again...
But you're right. I'd be better off switchable gain setting then a boost on it's own.
Hey wait ... I think I have one of those coming!

[ChrisM]

You could do it with a 4PDT and have no LED indicator

Or you could do it with a SPST switch, LED indicator and 2 relays.