This is the circuit for the HM-10ª, an instrument sold by Heathkit. The circuit is from a Radio Electronics from May 1963. The indication is by an analog instrument.
This circuit is suggested by National Semiconductor and is based on the LM3900, a quadruple...
This circuit for the radio amateur also includes the beep effect when changing. The circuit is...
We found this circuit in Radio Electronics from October 1968. The circuit drives headlight bulbs...