This video is the continuation of my previous video DIY variable linear voltage power supply,if you haven’t watched it yet I recommend you watch it first as a lot of things are related.
Link of part 1:
So without further delay lets jump right into it.
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Step 1: Link for the Video !!
Step 2: Building the Enclosure
I used a pitch plywood with 5mm thickness for building the enclosure.Afterwards I marked the respective dimensions of each part on the plywood and then cut it out using a hacksaw. A band saw would be a perfect cutting tool for this project.Then I had to sand down the edges using a sanding block due to some imperfection.After that I used wood glue to stick two pieces together and continued doing that till I get my enclosure.You also use small nails to join the pieces,but I still recommend wood glue as there is no chance of splitting the wood.
Then I marked the necessary holes for the two banana plugs,the power led and a switch and drilled them out.Now it was time to fix the voltmeter on the inclined side of the enclosure.The dimension of the voltmeter was measured and transferred it to the plywood.
All of a sudden I realised that I made a very stupid mistake,I forgot to place the potentiometer. So the solution was to place it beside the voltmeter.
After all the markings were done,the cuts were also done for the voltmeter and the potentiometer. Firstly I drilled holes in the corner so that it gets a bit to cut out the rectangle piece using my handsaw.After two hours of this madness the voltmeter was a perfect fit but not the potentiometer so I used a bit hot glue.
I shortened the shaft of the potentiometer otherwise it would stick far out from the surface.
Step 3: Assembling the Electronics.
Now solder the dc output wires from the power supply module.Then take a perfboard of suitable size and place the components as per as the schematic(the schematic is in the part-1,do have a look).
Link for the part-1-(https://www.instructables.com/id/DIY-Variable-Linear-Voltage-Power-Supply-Part-1/)
Try to place the components as close to each other and try to avoid solder joints.There is one electrolytic capacitor which is polarized to make sure you place it correctly.
After that solder the potentiometer wires just along with the resistor on board so that it forms a voltage divider format and also join the voltmeter wires on the perfboard.
Now drill a hole on the back side of the enclosure so that you can feed the mains wire through it.Afterwards solder the mains input wire to the power supply module in series with a switch(ie the power switch).
Once you know everything is working the way you wanted its time to pack things up.Before that make sure to attach the heat sink to the lm317 and tag a zip tie so that mains wire don't slip out.
Step 4: The Project Is Complete !!
Now lets give it a test,place a multimeter in parallel with the power supply so that you can measure the voltages.By rotating the knob we can see the voltage is quite accurate just an error of 0.1V sometimes which is acceptable.
Now coming down to the price this power supply was made under $10.So with at this price it provides a decent performance.
I hope you enjoyed this project.
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Untill next time.