Switch Idea

[kurtlives]

I am modifying a pedal...

I want to add a switch to select between two caps and the clipping diodes...

When the switch is flipped to one side a LED is added to the clipping section and a bigger cap is added. Other side of the switch selects a smaller cap and different diodes.

My first thought was just do the switching using SPDT style...now do that but with a DPDT....Then half the switch does the diode business the other half deals with the caps...

Then I remembered the lugs were internally connected...

How could I work this out with one switch?

[cheeb]

Are you trying to get two combinations?
1. LED and Cap 1
2. Diode config 2 and Cap 2

or four?
1. LED and Cap 1
2. LED and Cap 2
3. Diode config 2 and Cap 1
4. Diode config 2 and Cap 2

[kurtlives]

1. LED and Cap 1
2. Diode config 2 and Cap 2

Basically LEDs and a bigger input cap for a FAT sound and some other combo for a different sound.

[MusicAudio]

You could always get a 4PDT. They're expensive as far as toggles are concerned; but would certainly do the trick!

[kurtlives]

Uh that's way overkill I believe...

The "centre" lugs are still internally connected anyways.

[The French connection]

Rotary switch? Take more space than a toggle.

Dan

[cheeb]

Sorry. I've thought about it, and since those things go in different parts of the circuit, I can't think of a way you can do it with one switch. I hope somebody can, though, for your sake and because I'd love to know it to save money and space!

[ashcat_lt]

Uh that's way overkill I believe...

The "centre" lugs are still internally connected anyways.

Since when?  What switches are these?

[kurtlives]

Can you explain how it works then? Thanks..

[calpolyengineer]

In a regular DPDT switch, the center lugs are not connected to each other internally. Both sides of the switch are isolated from each other. As for your switch situation. I think it would work if you connect one side of the clipping diode section to a center lug and then connect the different diodes on the outer lugs and have both diodes connect back into the circuit. And do the same thing with caps on the other side of the switch. This way, the switch will route the signal through one or the other diode/cap. It should be a bit like so:


original circuit                 new circuit

                                              |----|>|----
                                                                \
-----|>|-----                    ------ |                  ---------
                                                                /
                                              |----|>|----

this of course only shows half the DPDT but the other half would be the same except with capacitors.

-Joe

[kurtlives]

To be honest I didnt understand what you were saying at all...

If the the lugs arent connected internally that is promising... Ill need to do some experiments.

[earthtonesaudio]

If it's a DPDT the lugs shouldn't be internally connected.  If they were, that would make it a SPDT.

[kurtlives]

Of course...DOH...

Then Ill just use half the DPDT (SPDT) to switch diodes and the other half for caps...

[MusicAudio]

Ok, so I thought about this a little more and you're going to need at least a 3PDT to do this. I'll try to illustrate as best I can.



If you only used a SPDT for the diodes (what you would get from using a DPDT for the whole thing) then the anodes of diode set 1 and diode set 2 will always be connected. If I'm correct in assuming  you're using the diodes as clippers then you need a dedicated DPDT for them.

So 3PDT would work, but if you're concerned about voltage buildup and want to add pull down resistors for the capacitors then you'd need to go with a 4PDT; that bit is up to you, it may not be necessary.

Hope some of that is useful!

mike

[d95err]

I'm still not 100% what we're trying to achieve here, but I'm 99% sure DPDT is enough. The 3PDT shown above seems way overcomplicated. We can obviously throw away the middle pole and connect "input" and "output" (they're connected at all times anyway in the 3PDT above). So that leaves just two poles necessary.

Another way of looking at it:

First of all, to change input caps we only need SPST. Put the caps in paralell and use the SPST to remove one of them, or put the caps in series and use the SPST to short one of them.

That leaves us one pole to do the diode thing, and I can't think of any case where a double throw switch pole couldn't do this. Even a single throw switch may do the job here.

[MusicAudio]

I'm still not 100% what we're trying to achieve here, but I'm 99% sure DPDT is enough. The 3PDT shown above seems way overcomplicated. We can obviously throw away the middle pole and connect "input" and "output" (they're connected at all times anyway in the 3PDT above). So that leaves just two poles necessary.

Haha, you're exactly right. How did I not see that!

Please disregard all the nonsense above!

[earthtonesaudio]

More nonsense...

[yodude]

I'm not totally clear on what we're looking for here, but here goes anyway.

A DPDT has 2 rows of three poles.  Let's identify them like this:
11 12 13
21 22 23

Here are the switch positions:
Position A
11-12 13
21-22 23
Position B
11 12-13
21 22-23

So maybe you can do this?
11: feeds in front of on board clipping
12: pulls from front of on board clipping
13: goes through alternate clipping then feeds in behind on board clipping
21, 22, 23 similar
(Important note: Need a break in the on board circuit between the pads connected to 11&12 and 21&22.)

In Position A, the signal goes up to the switch and right back down to continue through the on board circuit.  (The switch is a bridge over the "break between the pads".)
In Position B, the signal bypasses the on board clipping and is forced through the alternate clipping.  There might be some capacitance or other weirdness as some signal tries to go "backwards" through the on board circuit when you switch over.

Of course, I don't really know what I'm talking about.  Anyway, food for thought.

I think we could all benefit from two schematics: one for each configuration you're trying to achieve.  Good luck.

[kurtlives]

ahh...mubo...jumbo..lions tigers and bears...

Alex understands my way of "thinking"...

That's what I was trying to explain all along and ask if it would work.

Thanks