Q: using jacks for switchable components?

[circa1988]

Hello,
I have a question that's been gnawing at me...is it possible to attach components to 1/8 or 1/4 jacks, in order to make them switchable? I'm thinking something like little pods where you could swap things like pots (obviously this is done in a way when there is an expression pedal jack), but also capacitors, transistors, diodes, etc... easily and from the surface of the pedal rather than having them socketed on the inside. Would this create a shielding nightmare or some other problems (perhaps it would affect the resistance)? I know this will probably seem absurd to some folks, but it could also be really useful, and I have never heard of any company doing this...so I have been wondering if it's possible or if it would cause too many issues. As an example, the idea originally occurred to me when trying to decide between a potentiometer and a photo resistor in a design...I couldn't decide what size photoresistor I would like to use &/or whether to twist two or more together. & then I thought of switchable expression pedal jacks and wondered if I could just solder the photoresistor directly to a jack & use it. I suppose I could just do trial and error, but I would rather seek some advice about how this will actually affect the circuit....thoughts? If this is quite problematic, is there any way to address potential pitfalls?

[EBK]

The main potential problems I foresee are cosmetic.

Use a tip/ring/sleeve plug so you have two non-grounded terminals to work with if you need them.

The only technical problem that jumps out at me is the momentary shorting of the contacts that would occur as you are inserting or removing the plug.  Think this one through a bit. 

As for shielding, cover your add-on components in foil or conductive tape electrically connected to the sleeve contact of your plug, and you'll be fine. 

[RickL]

The old TC Electronics TC XII Phaser used this method to change the range of the phasing. A 1/4 inch plug let you change the capacitor that set the range. Mine doesn't have any issues with noise. I wonder if it would work on a chorus/flanger to give different delay ranges?

[GibsonGM]

Worked for Ma Bell.....

[EBK]

Worked for Ma Bell.....

A little too well....

[Mark Hammer]

The old TC Electronics TC XII Phaser used this method to change the range of the phasing. A 1/4 inch plug let you change the capacitor that set the range. Mine doesn't have any issues with noise. I wonder if it would work on a chorus/flanger to give different delay ranges?

Hah!  That is exactly the first thing that sprung to mind when I saw the subject of the thread. 

On the one hand, you have to wonder why it wasn't adopted more.  On the other hand, pedalboards have gotten so cluttered and tight, I'd imagine that anyone owning one of those TC pedals  likely keeps it off the pedalboard.

[bool]

The old TC Electronics TC XII Phaser used this method to change the range of the phasing. A 1/4 inch plug let you change the capacitor that set the range. Mine doesn't have any issues with noise. I wonder if it would work on a chorus/flanger to give different delay ranges?

I still have mine (pedal). But lost the plugs somewhere/somewhen.

Which precisely is the main drawback to the method as I see it.

[Fender3D]

TC XII's plugs allow you to change LFO's waveform (sine / hyper-sine) and its depth.
You may use them to sync the pedal with another sibling, or use a "manual" pedal control.

https://tcelectronic.zendesk.com/hc/en-us/article_attachments/212851588/TC_XII_owners_manual.pdf

[circa1988]

Thanks for not laughing me out the door, heh, I appreciate the responses. I don't necessarily see this having huge commercial appeal, if any, just thought it would be a cool concept for those of us who like to experiment with sounds at whim. I didn't consider the issue with shorting and the possibility that this could actually cause damage if it happened while the pedal was powered, so that is helpful to think about. Ideally, the components would only be swapped while the power is off. And of course, it would be tastefully done aesthetically if possible...I was thinking perhaps of using small tubes or canisters, either made from metal or with some form of foil wrapping. I don't know why this idea appeals to me so much, when one could also just use internal sockets...perhaps it's because the things I have built thus far ended up in cramped enclosures and taking them apart is sometimes messy business. I think I like the idea of the basic pedal being in a stable "if it's not broke don't fix it" state, with a few of the components being ever changeable. I sort of also liked the idea of building things with a window into their workings...for example, mounting the transistors and/or diodes in a distortion circuit in a clear glass or plastic bubble (which would especially be cool in the case of LED diodes which glimmer as they distort). But I'm not sure if this can be done without creating shielding problems?