Short Wave Converter (T987E)

The conversion range of this circuit depends on the coil. The circuit uses two tubes, and the power supply is not provided.

Polarity Test (CB14701E)
This polarity test or indicator indicates the polarity of a power line by LEDs. The circuit is...
Digital clock MM53149 (CB24361E)
This is the circuit of a digital clock published in the January 1975 issue of Radio Electronics magazine....
Powergrid timer (CB9364E)
Found in an Elektor from the 90s, this circuit can be powered directly by the power grid. The...