Build a Mini Pole Pig




I thought it would be cool to make a mini distribution transformer and one day i just happened to have all the supplies to make on so i decided to make an instructable on it.

this is not a high voltage transformer, it runs off of the mains to whatever voltage/current the transformer you will be using for it.

-=there are exposed terminals so be careful, i take no responsibility for any damages=-
-=if you dont understand something look at the pictures before you ask about it=-

Step 1: Materials

you will need :
a case, i used a paper salt container. must be able to fit your transformer 
a transformer with a center tap, has three leads or more (you will only use three)
some electric fence ceramic insulators
3 medium bolts 
3 rubber washers to fit the bolts
2 small bolts or machine screws 
3 metal stripes that can screw onto the bolts 
electrical tape
white or grey paint

Step 2: Prepare the Case

Rip off all of the labels and make it clean, you can sand it down to remove any rough spots.
Then cut off the top and drill three holes for your output wires, a little bit smaller than the bolts your using so they will remain tight (space them according to the size of the washer you are using), then drill two holes on the top for your input leads just make sure they are not bigger than the insulator your using. Then paint the lid and the case white or light grey. 

Step 3: Preparing the Output Terminals

After you finish with the case get the bolts, washers, and metal strips. The metal strips should have a hole that can fit on the bolt and another smaller hole on the other side of the strip to make it more realistic, i dont know that things i used are called but they look like they are for hanging something.

Screw the metal strip on the bolt, then the washer, and then screw it into the pre-drilled holes.

Step 4: Preparing the Transformer

On this step we will insert the transformer and connect the output terminals.

You need a way to keep the transformer secure so glue it or do what I did, i found a piece of foam, i cut it to fit the case, i poked holes on aether side of the foam where the transformer will be and tied it down with cable ties. 

Now for connecting the output, connect the ground to the middle terminal and the other two wires you will be using to the free terminals. You can't easily solder wires to a bolt in a cardboard case so i twisted a soldered copper wire around the bolt and wire and soldered those so secure them.

Step 5: Preparing the Input Terminals

Your almost finished with the inside!

Take your two primary wires and feed them through the two output holes in the lid, if you dont have any reason to open it up now is a good time to wrap about 3 turns of tape around the cut. 

Next put the insulators on the input wires, on real transformers they are at a slight angle so i used some epoxy putty to fix them in the correct position. 

Next cut the protruding wires and solder them onto the small bolts or machine screws and fit them into the insulators.


Now just connect your mains to the input terminals, and just like the big ones you should be able to connect it backwards to get a higher voltage. If you want you can use a fine sharpie pen to make details an markings such as the ones in the picture.

Thanks for looking!



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    19 Discussions


    8 years ago on Introduction

    I think I'm going to have to build my benchtop PSU to look like one of these. Trade out those bolts for similar-looking knobs.... Yeah, I think that'll look awesome.


    8 years ago on Introduction

    Nice looking rig, I like when DIY tech has some style. The big guys are probably expensive because of the price of copper, and they take quite a lot. Years ago PG&E left a huge, brand new pole pig on my roadside for a couple weeks...I was SOOOO tempted to liberate the thing but I'm just not quite that depraved. It would have been great for a tesla coil input...

    1 reply
    Jimmy ProtonDrSimons

    Reply 8 years ago on Introduction

    I've seen how they make em and it it looks pretty simple and yes they do have a lot of copper but i dont think its enough to make it cost more than $1000. Thant's epic, I probably would have got it but I would most likely get it a lot of trouble.

    Dream Dragon

    8 years ago on Introduction

    There's many reasons why the "real thing" is very expensive, but they do work very much like your model. It's a really nicely documented instructable, and it delivers an end result that has some style. It's not entirely safe, because of the exposed terminals you quite rightly warn about, but if you're messing around with electricity like that you really SHOULD respect what you're doing already and that should present no problem to a sensible experimenter.

    I would have reservations about putting it under heavy loads, because those things can get seriously warm and card is flammable, in a confined space do you notice a problem with heat build up?

    1 reply

    sorry, it never said i had a new comment but yes, they are used in the grid to step about 1000V to 120V and 240V.

    thank you for the reply i am now more interested,in designing a shed with wind generator supplying my power i might see if this is feasible to include in my plans for the more powerfull tools

    You won't need a Transformer for a Wind Powered workshop, just really big battery banks. You may need an INVERTER, if you intend to deliver the equivalent of "Mains Power" to your power tools, but such a solution is very inefficient and it only takes a little creative engineering to completely eliminate the need.

    probably not because full sized distribution transformers use up a lot of power and the put out a lot of power

    The oil is to keep it cool and its an excellent insulator. I couldn't put oil in mine because its paper but if you were to make it out of metal you could

    Yes. I was shocked when i saw you used cardboard because I thought you were going to fill it with mineral oil!