This 5-tube hi-fi amplifier was found in an American publication from 1947; The output is in class B and the circuit uses a source with transformer.
This Schmitt optical trigger with LDR was found in old documentation. The relay must be sensitive, or an...
We found this circuit in the January 1997 Electronics Now magazine. The triac determines the...
This transmitter uses a small loudespeaker (FTE) as microphone and can send the signals to...