This circuit with three transistors was suggested in a Radio Electronics magazine from February 1963. The transistors are types of the time. Power comes from a 12 V battery.
This is a different circuit for a component from the past, the zirconium arc lamp used in...
This circuit uses a FET to drive an LED with constante currente. The current up to 20 mA can be...
This circuit uses a phototransistor as sensor. The changes in the resistance of the transistor,...