The circuit shown is for testing both signal diodes (low current) and rectifiers (high current). The circuit is from a 2000 Poptronics, and the transformer has a secondary winding of 100 to 300 mA.
This circuit is from a Popular Electronics from the 90s. The integrated circuit admits equivalents...
This very interesting project was obtained in a 1980 publication. It consists of a device that is...
This circuit beeps when the sensor is triggered by the opening of the freezer door or other...