We find this circuit in a 1980s Linear Technology documentation. The circuit can be implemented on the basis of more modern equivalent components.
This simple two-transistor capacitance meter uses a 50 uA microammeter as an indicator instrument. The...
In this alarm R1 and R2 can be 10k. The SCR is any 106 Series SCR and V1 is an oscillator buzzer....
This circuit, which was common at the time, was found in the February 1973 issue of Radio...