two effects in one box, toggled by switch, shared volume knob

[Juppstein]

So, I have a Tonebender MkII I with a voltage inverter that did some time ago. Now there is some wee bit of space left in the enclosure that would allow a one knob fuzz to go in there as well (Coloursound Fuzz) but there is no space for an additional footswitch.

Is there a way to have a small toggle switch that alters between either the Tonebender or the Coloursound and the Volume pot is shared between the two? So that the only thing I have to add is the Coloursound plus a swtich and some wires?

[Focalized]

I suppose a 3 pole on/on between the stomp switch and the two effects. If you want an LED for each effect it would get more complicated and you say there's no room for a stomp sized switch. Let somebody else confirm that.

Also not sure about a shared volume but if that's possible by just wiring both to the pot you might find the volume will differ between the two fuzzes. Is there room for another pot?

EDIT. Don't know what layout for you tone bender is but that usually has a 100k volume and the one knob has a 500k.

[idy]

the different values for volume pots is probably not critical.
You would only need a two pole switch, unless you want to add an LED for the two circuits.
You will have a volume knob with its wiper feeding your existing stomp switch. Your DPDT will select whether the wire on your stomp that goes to your circuit input goes to coloursound or TB. The other pole will feed the output of your chosen circuit to the volume knob.

[Juppstein]

Thanks a bunch to the two of you. It worked out quite nicely in the end with just the dpdt switch that needed an additional small hole in the enclosure. Tonebender and Colorsound nicely boxed and done. Thank you!

[duck_arse]

pardon my intrusion, but what year was that photo taken, 1988?

[antonis]

I think 1989, judging from Knipex Side Cutter..

[dano12]

Volume pot is shared

One uses 100kA, the other a 500kA. If you could standardize, maybe a dual pot?

what year was that photo taken, 1988?

Those clicky IBM keyboards are hot lately. They never die and the layout has never been bettered

[PRR]

Those clicky IBM keyboards are hot lately.

Yeahbut-- that's not a "clicky IBM" keyboard. I was using the cast-off IBMs of a university well into the 21st century. Many small differences, so I don't even think it is a deliberate re-issue (they exist) or clone.
Ah, it is an Amiga, the other 1980s keyboard worth keeping.

[Juppstein]

Volume pot is shared

One uses 100kA, the other a 500kA. If you could standardize, maybe a dual pot?

Yeah also thought about it, maybe when the next parts order goes out I might add a dual gang.

[Juppstein]

Ah, it is an Amiga, the other 1980s keyboard worth keeping.

Yup, an Amiga 1200. I'm a bit into retro computing and since there's been a lot of development lately for the Amiga I decided to put mine back on the desk 😁

[Juppstein]

Looks like I ran into some trouble. I just managed to fry a 7660 and a MAX1044 and I think it might be due to me missing something important.

So my setup is in terms of singal routing a  dpdt switch that alternates between the two circuits for effect input and volume pot input. Then I have the +9V going to the Colorsound Fuzz and another lead going to the voltage inverter using the 7660S/MAX1044 where it gets flipped to -9V and going to the Tone Bender.

When I put in a new IC and plug the power, the whole thing works about 5-10 minutes, after which volume slowly starts to starve/decrease and the IC gets REALLY hot to the touch. Shortly after, the IC is dead. It doesn't go with a poof and smoke, so it wasn't even spectacular :/

Here is a box shot showing the whole debacle. Sorry for the mess in there, I was tweezing around looking for shorts and similar errors. 

[idy]

That is something I should have brought up. you are running a positive and negative ground in the same box, there could be trouble. Without a schematic of how this is being done it is hard to wrap my head around.

[Juppstein]

Yeah that was something I was asking myself as well, but due to me being a noob I obviously didn't give it enough thought.

Basically its the pcbs for the one knob fuzz and the tone bender mk II from tayda. I had a stripboard version of the Tonebender in there before but given I had the pcbs laying around catching dust I thought I'd put everthing into this box.

as per this thread, the two poles of the dpdt switch between the  circuit input / volume pot input of the two pcbs. My gut feeling is that this might be the point where the two polarities collide, no?

https://www.taydakits.com/instructions/one-knob-fuzz/pages/designators-and-components--15

https://www.taydakits.com/instructions/tone-bender/pages/designators-and-components--35

https://diyeffectspedals.com/builds/reverse-polarity-voltage-inverter/

[Matthew Sanford]

I know you already put it all together, but you could rework the positive ground (the tone bender?) with This brilliantly laid out info.. I did that with Tayda's DRM PCB, had to use a wire or two to reroute, but it turned out nicely. You shouldn't need to change too many connections.

[Juppstein]

oh nice, thanks for the link. Well ripping the PCB out should only take a minute or two. Then I'll see if my brain is able to process those instructions. I am not that far yet into electronics so it will be quite the experience I guess:D

[Matthew Sanford]

He lays it out pretty well for a fuzz face w/PNPs. Just pay close attention to what switches from -9v to ground, and what stays on ground. Remember that "ground" in a positive ground circuit is +9v to common understanding. Ground, as I've learned here, doesn't mean 0v necessarily but is arbitrarily set as the return path; the difference of 9v between the two is what matters. Ground throughout all circuits that join should be the same voltage.

Hell, it may even work to put the -9v from the positive ground circuit to ground in the other one if you don't use something to give -9v and instead wire the power supply backwards on that circuit (+9v to ground, ground to -9v - from wall wart)...but I don't know, kind of beyond me, and signal returns on the positive ground would feed in the positive supply on the other side, so scratch that.

Breadboard it once you figure it before ripping the circuit up if you have parts