Power Supply With PWM Generator and Load Switch

Hi guys, today I want to show you, how easily I made useful power supply for my hobby electronics projects using power supply modules. It doesn't require much knowledge of electronics to put it together and that's why it's also a good project for beginners.

It has an output up to 30V and it's capable to provide 5A of current to supply your circuits. I also added signal PWM generator module with various outputs and in combination with a MOSFET it can produce modulated power signal. With that kind of signal you can control DC motor speed, dimm an LED, etc.

Now that I told you everything about it, it's time to build it! :)

To make this power supply I used the following tools:

• cutting pliers
• dremel tool
• hobby knife
• soldering iron and soldering wick
• thermal laminator (not necessary)

Also you'll need these modules and materials:

• Digital adjustable power supply module
• Adjustable Signal Generator Source
• Switching Power Supply which has 36V 6A output
• DC-DC Buck Converter Step Down Module
• Banana plug socket

• Terminal Power Socket with Fuse Holder (and a fuse of course)

• Electronics enclosure of your choice (pick the right measures to fit everything in; I chose

  260 x 190 x 85mm because of power supply size)

• MOSFET transistor (has to handle at least 5A at 30V and 10V (or less with additional resistor) at gate pin; SSR which is in the picture is not the right choice)

• Thermal laminating pouches (not necessary)

• Double sided tape (not necessary)
• Some wires, screw terminals and crimp connectors

FRONT PLATE:

At first I cut out the panel plate. You need to take measures of your instruments, make cutouts for your them and drill holes for banana plugs. I made my task simpler by drawing panel in Microsoft PowerPoint. There are some helpful features in PowerPoint, that help you draw in scale when inserting a shape. Draw everything you need with typing in the right measurements (holes for instruments and plugs). Print it and stick it on the plate with easy removable glue or tape. Since every printer has different settings you'll have to find out the scale in which your printer should print your page. In my case it was 116%. After that, cut openings with dremel tool, drill the holes and peel of the template.

Optional: I also made a panel cover with designations on using template for cutting. Some designations were added and colour was changed (refer to the picture). Then I inserted template into thermal laminating pouches and let them through laminator. Then stick panel cover to the plate with double sided tape, cut unnecessary edges and make some holes. Mine turned out pretty well :)

BACKPLATE: Draw the shape of power connector to backplate and use the dremel tool again. The connector should fit, simple as that :)

After you finish front and backplate you can start putting components together. The first thing to do is to set up the power supply. You have to prepare power input cables, put crimp connectors on and screw them in terminals of supply; If you're new to power cable management look at the picture which explains current IEC standard.
When you secure power cables to terminals add different crimp connectors on the other side and connect them properly to power plug. You'll also need cables on DC terminals of that same supply to power up modules.

Next thing to prepare are banana plug sockets. Solder some wires to plugs and make sure, that you put plastic parts off so they won't melt during soldering.

Then you can fit those, switching power supply, adjustable supply module and signal generator on the plate. I also secured the big DCDC supply with some screws, other components just latched in.

Run wires from + terminal of switching power supply to + terminal of adjustable supply module. The same thing is with negative one (-). Make sure that you don't use too thin cables, since 5 amps could flow through them. The signal generator module works on 10V so I put DCDC step down module between it and main power supply output. With a flat screwdriver you can adjust the output of stepdown module to around 10V, which should be okay. I also soldered stepdown module on FR-4 breadboard alongside to some screw terminals for easier assembly. I additionaly adjusted main supply output from 36V to 32V, because supply module is specified for that voltage.

Don't forget to connect your banana plug sockets to prefered outputs of your modules!

Load switch: To use MOSFET transistor as a load switch for PWM generator refer to schematics in the gallery. You want to drive the MOSFET through PWM terminal from generator so you must connect it to the gate pin. The other wiring depends on what type of trasnistor you have (P-type or N-type); again, refer to the picture of schematics. I also screwed on a heatsink in case it heats up while supplying more consumable loads.

After that, check all of your connections and make sure that everything is connected right. For the best measure it with multimeter. Then you can turn on the power supply and connect your first circuit to test it.

P.S.: I didn't make any schematics or plan, I made all of wiring on the spot. But if you're not so confident in your knowlegde, I'm attaching a simple and colorful wiring diagram with photos :)

If everything went well during testing and you don't see any smoke you've done a great job!

The only thing left to do is to put everything in its place and secure the enclosure with belonging screws :)

Afterthoughts: I think that this power supply is great for beginners at electronics, because it doesn't require too much of complicated knowledge to make and it's easy to operate. Another reason is that it cost me around 70€ ($85), which is not much for a variable supply and PWM generator in one enclosure!

The only thing I would change is power supply module and replace it with an upgraded one. It has USB and bluetooth connection, so it can be controlled via PC. Here's the link.

I hope I made this instructable understanding and you enjoyed in it :)