Interesting project, I’m not sure if the vactrol route will work out definitely want to see if it works. I’ve been thinking a lot about doing similar with a dsp approach. But if you want to stay fully analog, and you are doing the switching with relays, a quick and dirty solution might be to just turn the pots with servos?
I have the vactrols now and have made a prototype. I plan to film it when I try it with audio signals. At the moment I am trying to get the PWM/resistor values right so I get a reasonable simulation of a potentiometer. It may not turn out to be the most audiophile of solutions, but the journey should be fun and educational :-)
@@offbeatinstruments hope it works out. Another approach might be to use a PGA2311. It’s a hifi quality dual digital pot, which has built in zero crossing detection to get around the noise issue, and also op amps to get over the noise floor. It’s used in some high end equipment (I think there’s a quad version too). I might get an evaluation kit from eBay and check it out.
@@seanhayes2998 I did try before with digital pots and I got a lot of digital noise on the signal and they didn't handle the weak AC signal well. I am sure I was doing it all wrong and selected incorrect digital pots, but it's a long time since I have done any electronics (I used to be a video game repair man in the 80's). Vactrols are used in synths for signal modification and also in tremolo circuits, so I am hopeful it will work out.
@@offbeatinstruments Looking forward seeing your results with the vactrols. Yes with a digipot you’d need an op amp in there to match the pup impedance and a zero crossing system to avoid the digital noise (the ti chip includes both). Plus you would need separate digital and audio grounds.
I don't think Raspberry Pi wouldn't really suit this particular project, because it only has 4 hardware PWM pins, so controlling a number of vactrols would need using the software PWM, which is less accurate. My Arduino Mega has 16 hardware PWM pins, more than enough. My other reason for using Arduino is that I originally built it several years ago before the Pi, and I like the coding platform. If I were starting again I might evaluate Raspberry Pi, but I still think that Arduino is better for this type of embedded project, as it is more of a microcontroller, not a computer. Where an Pi might have the advantage is processing speed, that would help with the tuning algorithm
Not really, it was an unfinished guitar and the internals are impossible to find, so there was no way to make it original again anyway. It wasn't really saleable before and it probably isn't now, so nothing lost, nothing gained. Even fully complete originals aren't worth that much, they are too out there for most guitarists who just want their Strat/Les Paul/PRS/Tele In any case, everything I have done can be removed, and I haven't touched any of the fundamental parts that were there before.
@@offbeatinstruments interesting, i have occasionally seen parts for Electraglides for sale, including the motherboard, but only very occasionally. More often you see fretboards and pickups from them for sale. I've followed the prices for complete examples for a while (in the hope of acquiring one), at the moment, they go for around 1k if they have a working psu. Which is out of my league at the moment! How's the fretboard on yours? Iirc they develop intonation problems as the board wears
Interesting project, I’m not sure if the vactrol route will work out definitely want to see if it works. I’ve been thinking a lot about doing similar with a dsp approach. But if you want to stay fully analog, and you are doing the switching with relays, a quick and dirty solution might be to just turn the pots with servos?
I have the vactrols now and have made a prototype. I plan to film it when I try it with audio signals. At the moment I am trying to get the PWM/resistor values right so I get a reasonable simulation of a potentiometer. It may not turn out to be the most audiophile of solutions, but the journey should be fun and educational :-)
@@offbeatinstruments hope it works out. Another approach might be to use a PGA2311. It’s a hifi quality dual digital pot, which has built in zero crossing detection to get around the noise issue, and also op amps to get over the noise floor. It’s used in some high end equipment (I think there’s a quad version too). I might get an evaluation kit from eBay and check it out.
@@seanhayes2998 I did try before with digital pots and I got a lot of digital noise on the signal and they didn't handle the weak AC signal well. I am sure I was doing it all wrong and selected incorrect digital pots, but it's a long time since I have done any electronics (I used to be a video game repair man in the 80's). Vactrols are used in synths for signal modification and also in tremolo circuits, so I am hopeful it will work out.
@@offbeatinstruments Looking forward seeing your results with the vactrols.
Yes with a digipot you’d need an op amp in there to match the pup impedance and a zero crossing system to avoid the digital noise (the ti chip includes both). Plus you would need separate digital and audio grounds.
There are enough new raspberry pi options for this that I'm not sure I'd bother with Arduino.
I don't think Raspberry Pi wouldn't really suit this particular project, because it only has 4 hardware PWM pins, so controlling a number of vactrols would need using the software PWM, which is less accurate. My Arduino Mega has 16 hardware PWM pins, more than enough.
My other reason for using Arduino is that I originally built it several years ago before the Pi, and I like the coding platform. If I were starting again I might evaluate Raspberry Pi, but I still think that Arduino is better for this type of embedded project, as it is more of a microcontroller, not a computer. Where an Pi might have the advantage is processing speed, that would help with the tuning algorithm
@@offbeatinstruments Well I was actually thinking of the Pi Pico. which is a microcontroller board.
Kind of interesting, but i suspect you've taken about 800 bucks off the value of the guitar.
Not really, it was an unfinished guitar and the internals are impossible to find, so there was no way to make it original again anyway. It wasn't really saleable before and it probably isn't now, so nothing lost, nothing gained. Even fully complete originals aren't worth that much, they are too out there for most guitarists who just want their Strat/Les Paul/PRS/Tele
In any case, everything I have done can be removed, and I haven't touched any of the fundamental parts that were there before.
@@offbeatinstruments interesting, i have occasionally seen parts for Electraglides for sale, including the motherboard, but only very occasionally. More often you see fretboards and pickups from them for sale.
I've followed the prices for complete examples for a while (in the hope of acquiring one), at the moment, they go for around 1k if they have a working psu. Which is out of my league at the moment!
How's the fretboard on yours? Iirc they develop intonation problems as the board wears