Hi folks, I've been thinking about building a two-voiced guitar similar to the Godin models, except with the option of selecting pickups and tones for both outputs, and routing them both through a single stereo jack instead of dual jacks. I drew up some rough plans of the electronics on index cards, but would like some second opinions before I start in on the build.
Starting from the pickups:
Going with humbuckers in all three positions, with a small-form factor on one of them so that I can do a 24-fret re-position.
The next challenge is to split the signals into two paths, which I'll be doing with a set of MCP6004 op-amp ICs:
http://ww1.microchip.com/downloads/en/DeviceDoc/21733j.pdf
The datasheet has the schematic for a non-inverting amplifier, which I can make a unit-gain non-inverting amplifier by shorting Vout to Vin- as so:
I don't need to keep two wires after the opamps for the center pins, but I kept it twisted to make it clear what is what's double
I figure I can solder the resistors to ground directly to the pins on the back of the chip:
So now I have 2 sets of each pickup, which I can send to my control scheme of choice, a 6-way switch:
http://www.stewmac.com/freeinfo/i-0040/i-0040.pdf
I'd use a variation of the H/S/H scheme on page 5, with wires 2 and 3 of the middle pickup going to input A-2.
Which should get me two sets of selected pickups, to feed into the tone and volume knobs, using a variation of this:
http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=1h_2s_1v_2t_5w
I can keep the design clean by using concentric potentiometers:
After that I just need the supply power to the opamps, which should go something like this:
The NJU7775F is a regulator that takes a DC supply of up to 9V and outputs a 5V supply, which should be within the operational range of the opamps. The diodes on the control pin are so that it turns on when the ground of the guitar is actual ground, which should happen when-ever there's a 9V battery.
If anybody can tell me whether this would work, or suggest a way to make it so it only turns on when the cable is plugged in, that would be pretty awesome.
Starting from the pickups:
Going with humbuckers in all three positions, with a small-form factor on one of them so that I can do a 24-fret re-position.
The next challenge is to split the signals into two paths, which I'll be doing with a set of MCP6004 op-amp ICs:
http://ww1.microchip.com/downloads/en/DeviceDoc/21733j.pdf
The datasheet has the schematic for a non-inverting amplifier, which I can make a unit-gain non-inverting amplifier by shorting Vout to Vin- as so:
I don't need to keep two wires after the opamps for the center pins, but I kept it twisted to make it clear what is what's double
I figure I can solder the resistors to ground directly to the pins on the back of the chip:
So now I have 2 sets of each pickup, which I can send to my control scheme of choice, a 6-way switch:
http://www.stewmac.com/freeinfo/i-0040/i-0040.pdf
I'd use a variation of the H/S/H scheme on page 5, with wires 2 and 3 of the middle pickup going to input A-2.
Which should get me two sets of selected pickups, to feed into the tone and volume knobs, using a variation of this:
http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=1h_2s_1v_2t_5w
I can keep the design clean by using concentric potentiometers:
After that I just need the supply power to the opamps, which should go something like this:
The NJU7775F is a regulator that takes a DC supply of up to 9V and outputs a 5V supply, which should be within the operational range of the opamps. The diodes on the control pin are so that it turns on when the ground of the guitar is actual ground, which should happen when-ever there's a 9V battery.
If anybody can tell me whether this would work, or suggest a way to make it so it only turns on when the cable is plugged in, that would be pretty awesome.
