We found this circuit in an old documentation for radio amateurs. The circuit uses an analog indicator. The characteristics of the coils are given next to the diagram.
We found this timer for times of a few minutes in a 1974 Ferranti transistor manual. The relay is 37...
The SCR sector of this circuit can be powered by high voltage AC and instead of the LEDs we can...
This circuit was found in a 73 amateur radio magazine from the 90s. An LED extends the scale from 0...