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4 Voltage Bench Power Supply


I've built myself my own universal, adjustable bench power supply.

The main reason I built it is to experiment with TFT backlight panels that I use for my lightboxes.
I needed 5V and 12V to play around with the inverter boards and figure out their pin-out. I considered buying a bench power supply. But prices were too high, especially for ones with adjustable voltages. So I decided to build my own.

This one has 4 outputs. One 5Volt, one 12V and two individually adjustable outputs going from about 1.5V to 19.5V. Each can draw up to 1.5Amp with a total of 3.5A for all together. The input is a standard replacement laptop power supply 20V, 3.5A. With a stronger external power supply the total output current can be higher, up to 1.5A per output. But currently the 3.5A is more than enough.

Each of the adjustable outputs has its own little voltmeter built in.
The fixed voltage regulators are based on a 7805 for the 5V and a 7812 for 12V. The two adjustable regulators are based on one LM317 each.

And of course I just had to built an acrylic case for it. Here is the pictures of the various stages of building and the finished product.

This is the board for the fixed 5V and 12V

Starting with the adjustable regulators.

Both regulator boards finished. The smaller board is what I call the Power Distribution Board. ;-) It has the power input, connectors for the main switch and two outputs that go to the two regulator boards. It also has another small 5V regulator that provides the voltage to run the voltmeters.

This is going to be the holder bracket for the two voltmeters and two potentiometers.

The rear view of the mounted voltmeters. These were ready. I ordered them on ebay for a few quid; from Hong Kong. These are blue displays!!! ;-)

At last the acrylic for the case has arrived

Here with the threads glued in.

The thinner wires go to the voltmeters.