This low current source without a transformer is intended for applications where insulation is not important. The circuit has a 110 V (120 V) input and was found in old American documentation.
The simple transistor test shown in the figure can be powered by a 9V battery. The test is for...
This circuit is from an American publication from 1970. It uses a coal microphone, which is...
The maximum current of this circuit is 250 mA, its purpose being to replace 9 V batteries. Diode D1...