DIY Power Resistor





Introduction: DIY Power Resistor

First , hello , I am glad to be here on

This is my first instructable.

This is one simple way to create power resistor at home.
I needed 0,33 ohm resistor with some larger wattage so I decide to create one, instead of buying one. I always say, creating is much more fun then buying.

Step 1: Video

I created small video with these steps

Step 2: Coating Mass

You will need jointing filler to create mass for coating, to protect resistor wire from oxidation, and to provide heat transfer from wire to environment.

Step 3: Prepare Wires

You need one old high wattage resistor ( I had one 10W 100 ohm ) to use wire from it.
You will have to destroy it, and take high resisting wire of desired length-resistance. You also need some copper wire as connectors.

Step 4: Prepare Mold

Also you will need small piece of tin to create mold.

Step 5: See Results

This is semi finished, and finished resistor after drying.



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    16 Discussions

    This is very interesting! What did you make using this homemade resistor?

    3 replies

    Thanks, I am creating variable power supply so I needed it on output stage.

    ha, that's exactly how I landed here. I need 12x 0.05 ohms at 100W.

    Yes, it is possible to create any resistance and any power.If one does not have precise ohm meter it is possible to measure , let say 2 ohms wire, and calculate with the length of 2 ohm wire desired resistance. Also combining wires in parallel we can get desired resistance and higher power.

    Thanks for this one. Actually, since I don't have those old resistors/resistor wire I'll try the pencil way. It's needed for a battery tester with something around 10-20 Ohms.

    4 replies

    you're welcome, you can try with pencil graphite rod, you just have to be careful since

    graphite rod is quite fragile.

    I have just tried it out. 1cm of graphite had around 10 Ohms. I connected it to my power supply with 5 Volt. And that made the resistance drop constantly so the 500 mA increased and soon crossed 2 A with nice little smoke clouds. It looks like I need some resistor wire which does not change that much when heated.

    Sorry for this :-) I did not have time to try this with graphite rod.

    You can check this web page where this guy noted that these graphite rods are actually NTC resistor, so that why you probable got this result, I am not sure.

    Anyway, for resistor wire you can try heating elements from some old hairdryer, old electric furnace...etc. but I think the best result is when tae wire from some old resistor.

    No worries. I simply heated it until it blew off. BANG!

    I'll probably go for my distributor. I need three 17 Watt resistors at 12 Ohms. Each at about 1€. My broken hairdryer is already on the dump :-/

    Might one also use a piece of graphite rod of the kind used in mechanical pencils? Anyone know the resistance of a 0.5 mm HB pencil lead, per centimeter?

    2 replies

    I just tried a measurement. 1 cm of 0.5mm HB rod had about 50 ohms, so it seems that one would need a very short piece, or a much wider rod, or a thin layer between 2 conductors.

    I did not try this, but the principle would be almost the same, except that we would have different way of connecting of resisting element to the connecting copper wire.

    Anyway, I don't if it is allowed, but I will give you link to a page where one guy tested pencil graphite on electrical resistance:

    When there are no electronics suppliers nearby, this is very handy to know. Thanks.

    1 reply

    You're welcome, and you are right, in my town there is no electronics shop, I wold have to drive 30-40 km ( and spend 10 euros ) just to by some of these.

    But I also like to make(and destroy :-) ) things , so this was both useful and fun to me.

    I hope this idea will be useful someone sometimes.

    I admire your determination and problem solving abilities in creating this custom power resistor, well done, it looks very profesional.

    1 reply

    Thank you,

    I needed few of these resistors 0,33 and 0,1 ohm and thought to buy them, but then I asked myself "can I make them?" and started to think about that and this is the result.