Here is stabilised power supply with short circuit protection. It’s an efficient 4-stage stabilized power supply unit for testing electronic circuits; and it provides well regulated and stabilized output, which is essential for most electronic circuits to give proper results. The circuit provides an audio- visual indication if there is a short circuit in the PCB under test, so the power supply to the circuit ‘under test’ can be cut-off immediately to save the valuable components from damage.

The circuit provides four different regulated supply outputs (12V, 9V, 6V and 5V) and an unregulated 18V output, which are selectable through rotary switch S2. The selected output is indicated on the analogue voltmeter connected to the outputs rails.
Source: Authorized by D. Mohan Kumar, ELECTRONICS FOR YOU, July 2004