Ian’s Bench Power Supply

This is my first attempt at documenting a project. Although this is not really a Linux project, the software application Inkscape was used running in Linux to design the layout template that was used to cut out the front panel of the power supply.

I guess one of the first ‘main’ projects of amateur electronic enthusiast is the requirement of a bench power supply. These days bench power supply’s seem very reasonably priced and it would have been all to easy to just click on the “Buy Now” button on my favorite auction site and for it to be delivered in the next couple of days. But wheres the fun and learning in that? So I decided to roll my own.

My requirements were:-

  • Three interdependently adjustable power supplies
  • Voltage adjustable / regulated
  • Current ‘adjustable’ / limited
  • Wide voltage range
  • Voltage and current indication
  • Mains powered
ItemQty
Bench case1
LCD Displays Volts and Amps 3 decimal place3
On/Off latching push button3
Banana plug sockets Black3
Banana plug sockets Red3
10K potentiometer6
M2 Nylon Hex Spacersbox >20
DC-DC Step Up Down Boost buck Converter LM2577S LM2596S – Current limiting3
Rocker switch 2-pin snap-in1
Figure 8 power socket1
Laptop power supply 19V1

Now for some pictures:-

Bench Power Supply – Front

The image above shows the front of the power supply. The red knobs control voltage and the blue the amount of current limiting. It was logical to be able to match the colour of the knobs with the panel display colours, i.e red = voltage and blue = current. The red LED above the blue knobs indicates that current limiting has been triggered.

Bench Power Supply – Back

The image above shows the back of the supply. To the left is a fuse holder and the figure 8 connector for mains power. To the right is the black power on/off switch and the three red “voltage-selection-reduction buttons” are used to limit the voltage to each power supply. When they are ‘on’ the voltage selection range it limited to ~1.3V to ~12V and when ‘off’ the voltage goes up to ~27V

Bench Power Supply – Top off

In the image above, located at the back of the left hand side of the case you can see the laptop power supply ‘brick’. This means that ‘high’ voltage is physically near ‘low’ voltage stuff I have done my best to “double insulate” all of the ‘high voltage connectors, i.e. covering them shrink wrap and other exposed parts with hot melt glue.

Bench Power Supply – In situ

That’s all folks

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