1-minute delay (CB21408E)

This circuit with PUT is from a 1967 General Electric manual. The relay must have voltage according to the supply.

RIAA Transistor Amplifier (CB19171E)
This circuit, from the 90's, is intended for operation with vinyl record players of the time, as...
Instrument Scale Modifier (CB4159E)
Using a zener diode it is possible to change the linearity of the scale of an analog instrument by...
Chime delay (CB9679E)
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...