Or just replace Q503 with a small signal logic level mosfet and call it a day. Heck, even a 2n7002 would do fine there in this particular case, although it's not logic level.
Or just replace Q503 with a small signal logic level mosfet and call it a day. Heck, even a 2n7002 would do fine there in this particular case, although it's not logic level.