We found this circuit in the October 1996 Electronics Now magazine. The circuit uses LDRs as sensors and drives relays. The relays must have voltages according to the power supply.
This circuit was found in the ON Semiconductor thyristor manual of the 1980s. As the drive is done by...
This simple preamplifier was published in Radio Electronics magazine in February 1958. The battery...
This circuit can use 20 to 100 mA relays with a general-purpose transistor such as the BC538. The...