This alarm circuit was found in April 1975 Radio Electronics magazine. The circuit uses a 12 V power supply and relay but can be modified to work with other voltages.
This relay driver or shield was found in a 1960 Sylvania transistor manual. The circuit is for...
This circuit is from an 80's documentation. The circuit makes use of a component of the era, the...
This modulated siren has frequency adjustment and modulation in the trimpots. For 220V use 1N4007 as...