Mihai contacted me by e-mail and he sent the circuit he designed, based on a PIC
with my program inside.
He has added the regulation of the input voltage, a check for low voltage (battery low)
and a variable frequency oscillator, to change the CW tone monitor.
To work properly with the external monitor circuit, you must download a slightly
modified version of the keyer program, v2.2a.
Download the YO7LHC circuit
along with IK0WRB keyer program v2.2a (adapted to this circuit)