This alarm with automatic shutoff was found in the April 1975 Radio Electronics magazine. The activation time is given by C1 and R3. The alarm uses series and parallel sensors.
This shield circuit allows recording of the signal from a serial output on a cassette recorder, with...
This Japanese radio receiver is from the 60s. It has 6 transistors and is powered by 4 batteries with...
The integrated circuit used is a voltage reference from Motorola. This configuration was obtained in...