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DIY Variac

Looking for a way to control the input voltage on a neon sign transformer... this was my solution.

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Looking at the neon sign transformer, I wanted a way to control the actual output. The easiest way was a variac, but I didnt have one. Sure, I could buy one, but what fun is that.


~Jessie
twitter https://twitter.com/ThunderSqueakAK

Looking at the neon sign transformer, I wanted a way to control the actual output. The easiest way was a variac, but I didnt have one. Sure, I could buy one, but what fun is that.

  • 1
    Step 1

    After some looking around I got this one for 30 dollars.

    bare variac

    It was bare, but that is ok. I looked around for a container for it, and could not find one that I liked. I considered building one out of wood, but chose against that as well. One option was to use a junction box from the hardware store, but those were 70 dollars. While I was looking for one that had the proper dimensions, I came across a toolbox and had an idea. Why not just use this :D 6 dollars and a peice of mdf and I think it might work. The people at the hardware store cut a peice of mdf the size of the “tray” that fit inside the box. I finished the rest of it with a small coping saw.

    box with mdflayout of parts...

    After some layout issues, I chose to just put everything on the mdf instead of cutting the toolbox. I cut the holes out by drilling the corners and again with the coping saw ripped them out. Since I was using outlet covers, accuracy isnt such a huge issue.

    holesfirst dry fitting

    Next was the wiring and mounting of the components.

    wiring viewwiring

    top viewclosed

    Then I secured the whole thing into the toolbox with a couple bolts and nuts.

    The initial tests were great, I used a light to visually see the effect of changing the voltage. To test the amp meter, I hooked it up to an electric motor. All in all, the project works like a champ. The lamp just didn’t draw enough current to really move the needle.

    Total cost of the project, 60 dollars.

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Adam Gulyas wrote 08/03/2014 at 09:49 point
I might build this, since I've been wanting a variac for a while. I like the toolbox enclosure.
Could you post links to where you bought everything, particularly the ammeter and voltmeter?

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ThunderSqueak wrote 06/24/2016 at 20:03 point

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Frenchcanadianflyfishing wrote 05/02/2014 at 05:53 point
Add a fuse somewhere and you are in the game... Looks good so far :)

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ThunderSqueak wrote 05/02/2014 at 08:16 point
Haha! yeah, at the time I didn't... I should add one ^^ Thanks for reminding me!

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