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 circuit, from the 90's, is intended for operation with vinyl record players of the time, as...
Using a zener diode it is possible to change the linearity of the scale of an analog instrument by...
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...