This circuit keeps a set of lamps permanently on, even when there is a power cut. The circuit can be adapted to use LEDs and the 12 V battery can also be changed according to the lamps or LEDs.
This configuration is from a 1987 publication, but it can be easily assembled today, as the...
This is a simple source indicated for powering low voltage projects on the bench. The circuit is...
This circuit is from Philips' 70s documentation. Transistors can be replaced by modern...