This circuit is better than the previous one in that the control is isolated by a transformer. The transformer has 110 or 220 V primary and 6.3 to 12 V secondary with 200 to 500 mA current.
Found in a 1990 Electronics Handbook, this circuit causes an LED to flash when the phototransistor receives...
This simple low current source for the bench was found in ancient American documentation. The...
In this circuit, a switch, reed-switch or sensor is used to control a half-wave alternating...