1. The power supply was the culprit in disabling all audio signal. (It also powers my processor/preamp)Not sure theoretically how an AC audio signal would cancel the digital signal through the processor's power(maybe inverted phase cancellation?)I had to run a separate power supply to get it to work.
2. I have only been able to get any sound with ceramic disc caps. I've tried electrolytic caps back to back(+ - +), metal film caps, and polyester film caps.
3. The more resistance, the stronger the signal is. (Because its a bigger load?)
4. The capacitance didn't seem to change sound level. I used as small as a 1nf, and as much as 0.5uf with no noticable difference.
5. Multiple caps in series seemed to increase the sound level just barely. While multiple in parallel greatly decreased it.
As for the variable resistor, it seemed to not make a difference. And the RLC method is for a low pass filter isn't it? I could try an LC method, but not sure how I would incorporate the resistance. Also, I've read places that a guitar's pickup is basically an inductor in series with a cap and resistor in parallel(RLC)
The op-amp circuit you describe.. by which you mean as a buffer to keep a specific resistance? That may be a good idea to try out, but would be sensitive to different pedal layouts(different IO impedance).There also seems to not be any 20hz high pass filters available in a small package. I found this schematic however:http://www.eeweb.com/blog/circuit_projects/20hz-to-200hz-variable-high-pass-filterMay be useable, but the schematic states 15v input voltage, and the tl072 is rated ±15v.Could I just swap for a lower voltage chip, or just run this with 9v?
Thanks for the help Far-seeker, you have really helped me out so far.
I see what you mean. Better to have tried and failed than to have wondered what if. I think I may default to using a stereo cable instead of mono. I'm trying to make something that would be easy to incorporate into guitars without much circuitry. Thought I'd try if it would just be something simple like a cap in line, you know?
But as for the stereo cable, I just need to make a sensing circuit for the pedalboard so it will stop supplying 9v power to the 2nd lead on the cable if a mono is plugged in. In this way, if the 1/4" stereo plug is used with a mono cable, the 2nd lug will connect to ground. I haven't decided on which method I may use: Use arduino to sense current, resistance, or voltage(I think voltage may be the easiest), or to just use a relay that will switch itself given the ground signal returns 9v, and then it will sustain itself there, then when powered off it will reset itself, or along the lines of that..Can't really think of much else than that.
But if I used the arduino's analog input to determine the voltage(with a voltage divider of course), would the AC signal hurt the input if only for a short moment? I would like to not use an inductor if possible, unwanted distortion and low freq. loss through the arduino to ground.
But onto the communication/wireless. I picked up 4 nrf24l01+'s on ebay for <$8, so my evil idea is to communicate the ardy's with a pair(1 on pedalboard, 1 on guitar) and then transmit that directly on the audio wire rather than air. I just wonder, from the theory you have taught me thus far, I could run the 2.4ghz signal over the audio lines and the +9v line, without issue, right? Or would I be better off running it on the ground line?
Now for the possibly crazy idea. For wireless, run that into another pair of nrf24l01+'s, but with an antenna. I don't know how I would go about amplifying that signal just yet though. Off to google I go!