A Lab Bench Power Supply is a crucial piece of equipment for any electronics workshop. It is great for testing components, motors, devices and circuits which require a particular voltage to operate without frying them. Having a need for a power supply which had a large voltage range 1~15V DC with an acceptable least count and high current delivery capability, I tried but could not find one readily available that would fit in my expense. Hence, I decided to make one myself, which uses a high power buck-boost converter for the variable voltage output.
The supply is based on a high current transformer, which steps down the mains AC voltage to 12V AC, which is then rectified and filtered through a bridge rectifier and a series of capacitors. The voltage is then fed into the buck-boost module, the output of which is connected through a digital ammeter+voltmeter combo to the banana connectors in the front, which allows easy connection to a variety of connectors. The output voltage is controlled through a high-precision, wire wound potentiometer, which gives a lot of control accuracy. Though there are two pots in the front, one of them was meant to control the constant current output, however it would start varying under high current loads. Hence, it was disconnected and is left only to maintain symmetry.
A fan was added along with a heat-sink to the buck-boost converter, as a safeguard against things getting too hot and damaged.
Multiple fuses, one for the mains supply on the input and one on the output were used to prevent from short circuits. This also ensured that if the power supply got short and left unattended, the fuse would blow thereby preventing any kind of hazard.
The enclosure for the power supply is a repurposed UPS (uninterrupted power supply) enclosure, which was shortened in length. Some L channel was bent and added around the front and back to act as a garnish and guard from the rough edges.