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.
We found this circuit in a 1977 radio documentation. The circuit uses TTL frequency dividers from...
In figure we have a three-phase AC motor control for voltages up to 600 V or 1200 V depending on...
The oscillator shown in the figure can generate signals up to 500 kHz and has good stability. Coil...