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 stable 20 MHz oscillator was suggested by the National Semiconductor's Linear Applications Handbook...
This buffer and driver is from the integrated circuit manual itself, the Linear Technology LT1206. The...
The transistors in this 1978 circuit can be BC548 and 1N4148 diodes. The electrolytic capacitors can be...