This DC-DC converter was found in old RCA documentation. The circuit operates at 15 kHz. The characteristics of the transformers were not indicated.
This polarity test or indicator indicates the polarity of a power line by LEDs. The circuit is...
This is the circuit of a digital clock published in the January 1975 issue of Radio Electronics magazine....
Found in an Elektor from the 90s, this circuit can be powered directly by the power grid. The...