This circuit was found in a 1965 Electronic Design. The transistors are of the time, but the circuit applies to modern equivalent transistors.
We found this circuit in the magazine Eletcronics Now of July 1994. The power supply is according to...
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...
We found this circuit in a 90's Radio Electronics. The low power circuit activates a 12 V relay...