It's been like fifteen years since I got out of the big truck and lost track of my CB sets, but I still miss listening to the cosmic wind all night long, and I almost regret that I didn't record a whole lot more of the incredible noisescapes that came out of that little speaker. I spend hours tweaking knobs and applying processes and never end up with the subtlety and complexity of some of what I heard when I just turn the squelch all the way down, volume all the way up and switch to channel nobody's talking on. Like, barreling down the road in the middle of haven't send civilization in hours and listen to the universe vibrate around me...
Anyway, I got to thinking that a radio tuner is not a particularly difficult circuit to build, and could easily fit into a pedal, but you need an antenna. Well, a guitar cable can act as an antenna. I'm thinking for safety's sake what we do is use an isolated input jack. We connect the tip to nothing, and the sleeve to wherever the antenna is supposed to go. Now all of the "shielding" of anything it's plugged into becomes part of the antenna, too. Plug it into a guitar and the pickups add to it. I wouldn't be surprised if you managed to get some string noise out of it even. But we're not listening to the 60 cycle hum that you would expect if you plugged this into an amplifier. We're going to demodulate that signal and listen to what's happening up in the CB band. Hopefully.
Then I got to thinking it would be fun if we could tune the thing with a foot pedal. Then I remembered I have a kind of broken VPJr around here somewhere and if the pot doesn't help us, the mechanism might.
And that's about where I'm at in the "design process"...
No, I'm not gonna get into all the nutz and boltz of how to do what you're contemplating - it's already been done to death, all over the web. I'll answer specific questions, but I'm not gonna anticipate, and spew a bunch of unnecessary blather all over these pages. But what the hey, I'll just suggest that you search on "how to build a radio", and see if that doesn't get you further along your path.
But I have to wonder..... why not just hit a pawnshop for a used CB radio? I'm not too sure just what you need a foot pedal for, but surely you can figure out a way to couple a foot volume control to the appropriate spot on a CB's circuit board, no?
And to cap it all off, remember - different radio modulation methodologies result in entirely different "background" sounds for each corresponding receiver. You might wanna check out things like CW, FM, FSK, SSB, QAM, any of the pulse modulation methods, etc.
Rule #1: All Lives Are Final. Make sure that the life you have just been issued is appropriate for your needs, before departing the womb.
Rule #2: In case you don't like the life you have, see Rule #1.
Most of the reason I wanted it in a pedal is that it would a compact, durable box with a 1/4" output that could go to guitar amps or other pedals or whatever without special cables or messing around. Plus, I was kind of interested in the idea of using the cable and/or guitar itself as an antenna, though I'm not really sure how or even if it would make a real difference. Then I thought about the volume pedal cause I have on sitting here and thought I might be able to use it as a tuning or at least fine tuning control to make it do different things.
It probably would be a lot easier to grab a used CB and hack into it. The push-to-talk microphone is a whole other toy of its own. Then I start to want two so I can make stereo recordings, but that's a whole other set of questions...
When I worked at Mother Clucker's (half block off Bourbon St), back in the kitchen there was this crappy little boombox. I would set it to the classical music (FM radio) station, but then it would drift a touch, and if each of the metal doors was positioned just right it would get to this point where IDK for sure what was happening, but it was distorted and modulated and seemed like side ands from nearby stations might have been fighting with the orchestral music and it turned into beautiful cascades of noise like nothing I've heard before or since. One day a new hire came back while I was elbow deep in raw chicken and "fixed" it for me by dialing it back into the actual station. I didn't yell at him too long, but most of it was language we don't use around here. He didn't understand, but he never touched that radio again.