TonyAme

No as you don't have a coupling capacitor in the audio signal path. The resistor would discharge such a capacitor when the input is disconnected.

Connections to 3PDT switch look correct. Since Teensy takes time to power up, audio won't be immediately heard when toggling bypass switch back-and-forth. If you're okay with this, no problem. Otherwise, a separate switch for power is needed...

Would using a 1M resistor here be useful for an anti-popping solution caused by a mechanical toggle switch? Thank you.

Updated the schematic with negative center power plug and 3PDT bypass switch. (I think I will just cut the trace that connects the "5V" pads to isolate the USB power from external 5V power supply.) Could use checking of my updated schematic if...

Thanks very much. I think I will do what you say; "You should isolate the regulator 5V output from the USB 5V source." I guess with a diode. And leave the Teensy/Audio shield in-circuit when programming. Extra copper or Thru-hole device is...

Okay. Removing Teensy+Audio board from circuit for programming will work. The down side of doing that is..., potential damage to Teensy. Please don't use a screw driver to pry it off a proto board (assuming it uses pins for mounting into a...

So..., how do you intend to program Teensy? Turning switch SW1 OFF is not a solution. Regulators don't like seeing 5V applied to their output pin. You should isolate the regulator 5V output from the USB 5V source.

I'll be removing the Teensy + audio board from the circuit whenever I program the Teensy. Is there something I'm not seeing in my schematic concerning the 5V input from the 7805 regulator? (I do often not notice obvious things when constantly...

Thank you. Will check out your stereo buffer, appreciate it.

A guitar with active pickups will have the buffer is already built in. Otherwise, i'd recommend a HiZ buffer. Plenty projects are available online. I've made a simple stereo buffer project which can be soldered on a perf board...

Thanks very much for that great info. I won't be using the usb port for power. This schematic is a preliminary design, but yes a bypass switch and a negative center power adapter plug is the electric guitar way to go. Appreciate the help, thank you.

@TonyAme, be aware that you can't connect 5volts from USB at the same time as 5V from regulator. They will fight each other. there are multiple solutions to this issue. You could add a jumper plug/pins to the 5V regulator output. Remove...

Really, no need for any buffer? Also, I have a passive filter circuit for the output as in the schematic attached, does it need to be connected to Out Gnd? Thanks very much, Tony

I'm experimenting. Would I need to add a pre-amp or op-amp buffer circuit before trying to connect a guitar straight into Lin of the audio shield? Would anyone know of a simple schematic for this? Sincere thanks, TonyAme