This is an amplifier circuit intended for modulating transmitters. The 5-tube circuit is from an American manual from 1947. The power supply uses a transformer.
Vz determines the trigger point for this protection circuit. The SCR doesn’t need to be mounted on a...
Varicap or varactor is the basic component used in this circuit of an American 80's documentation. The...
In this alarm R1 and R2 can be 10k. The SCR is any 106 Series SCR and V1 is an oscillator buzzer....