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.
The CMOS PLL used on this circuit is not very common. The circuit can be used to take out contact...
We found this circuit in the Radio Electronics magazine of February 1993. The main integrated...
This circuit was found in Motorola documentation from 1968. SCRs can be modern equivalents and the...