Powering PO via modular / Will these things run on 5 volts ?

Or should I order a 3v regulator ?

I’d go with the regulator just to be safe. Though there might be a thread where someone talks about how much voltage the POs can handle, too, seems to be in the back of my mind, now.

^ Agree. There is an onboard 2.5V regulator for the codec, but the EFM32 MCU seems to be powered from the batteries through a diode only (reverse polarity protection) and it can only handle up to 3.8V.

The @punji has spoken. He probably knows the most about the POs on this board and could rival TE I imagine!

^ Reverse engineering the PO-16 without killing it was quite a challenge. I had a lot of fun doing just that, even if I never complete the custom firmware…

Thanks! couldn’t easily find a 3v regulator in through hole package, got an adjustable regulator in TO-220 figured the heat sink tab will help since its going to dissipate 9v. It’s powering my pocket operator with 2.5v via the + & - pads at top of back of pcb & is working fine.

PS*** After running on my bench for 5 minutes the regulator is really hot! I guess I will attach a little piece of aluminum to it, put some hot glue on the regulator circuit’s trimmer to protect my PO from over voltage & call it a day.