A basic bench variac

[SurreyNick]

This is the result of today's labours - a basic bench variac.

It's only rated at 0.75A, but should be suitable for most vintage valve radios and test gear. It's quite compact, measuring a little under 8 in. x 5 in. x 3 in. in old money. It includes overwind and boosts voltage to 270V and includes an integrated 0-300AC voltmeter. All in, including all new components plus postage, it cost just £43.89 to construct, which I think is pretty reasonable.

Nick

[Mark Hennessy]

Nice job

I really must get around to housing mine in an enclosure. Right now, it's screwed to a lump of MDF, along with a 13A plug socket and a "Safeblock" - functional, but takes a lot of space on my small bench. I have an ideal box and I have a digital meter that does voltage and current - what I don't have is the time to make it happen. Story of my life, but I suspect I'm not alone

[SurreyNick]

Thank you Mark, I'm lucky, I have the time nowadays

I can see the advantage of having measurement of current as well as volts. Having seen t'other Nick's varic too, which includes RCDs, I can see a deluxe version coming some time in the future. For now however, this one will do.

So, I have the lamp limiter and the variac, methinks an isolation transformer is needed too eh!

Nick

[Refugee]

I built my 4 amp one into a case about 5 years ago. It was NOS but never got built into a case by the previous owner. I got it for free.
When I came to test it in anger it did not work and that was when I found that the brush was broken. No wonder it was free.
Obtaining a brush is almost impossible and making one is a very fiddly job indeed.
It is due to have a new output socket fitted due to the existing socket not gripping the plug hard enough so that it keeps dropping out leading to annoying losses of contact.
I will start a new thread with photos of the insides when it gets fixed.

[SurreyNick]

Did you actually manage to make a new brush? I can hardly believe it's possible. I take my hat off to you if you have/can do it.
Nick

[Refugee]

Yes I did make a new brush.
It is a sort of chisel shape and it took several goes working from a bag of washing machine brushes I bought for £1.99 from E-bay.
It was a very dusty dirty job like repairing a very old photocopier but it has been working fine until the output socket got a bit dodgy. There is also some wiring that needs altering too so perhaps in a week or so I will open it up for its first 5 yearly service.

[glowinganode]

Hi Nick, that's a nice tidy job.
If you haven't already, I'd strongly recommend adding a fuse on the output side.
Also a mains on indicator is a good idea.

Cheers, Rob.

[SurreyNick]

Thanks Rob. It does indeed have a fuse on the output side. The power switch is an illuminated rocker and acts as the 'mains on' indicator too.
Your post has reminded me, I must get around to posting the instructable for other newcomer hobbyists
Nick