Lab Power Supply

This bench power supply circuit is suitable for your electronic experiment lab. This circuit can be built no on a piece of copper-laminate. The Bench Power Supply was designed to use old lantern batteries, “D”, and “C”. This circuit can produce at least 12v -14v from  old batteries and cells. As a heat-sink, this  circuit uses a board. To connect the components, enamelled wire is used. To keep the transistor cool, it can be bolted. Here is the schematic diagram of the  circuit:

The zener is used to regulate The output of this power supply. So, there is voltage approx 1.7v across a red LED and 8.2v between the base-emitter leads of a BC547 transistor (in reverse bias). This circuit can give 0v – 9v at 500mA depending on the life left in the cells used. To indicate the circuit is ON, LED is used. The 10k pot is used to adjust the output voltage. [Circuit’s schematic diagram source:]