Found in the July 1994 Electronics Now magazine, this circuit drives a relay up to 12 V depending on the power supply. The transistor can be general purpose.
This circuit was found in an American 1980s documentation. It makes use of an unusual MOSFET today...
We find this circuit in American documentation from the 1980s. The accuracy of the circuit depends on the...
This circuit is from 1964 documentation but can be easily implemented based on current components....