Buying a variac?

Asking for a friend…
Really, it is not me, this person has been watching Repair Shop and is now worried about reinstating equipment that has been in storage for 15 plus years. A couple of audio systems, darkroom equipment and in particular a large quantity of studio flash equipment.
He doesn’t have a lot of money, cannot transport what he has, so is looking for a variac to gently try powering up. There is a massive difference in buying from RS and Amazon.
Does anyone have experience of the various items seen at the lower price please?

Don’t know which one he’s looking at on Amazon but a cheap one doesn’t halve CE marking or an earthed casing plus a foreign plug,
To me that’s avoid like the plague, how can they sell it like that Amazon

My fears as well, a little knowledge is definitely not a good thing.

Buying from RS will give you a product of known quality with all the documentation to back up that it’s a safe and reliable product. It will work out of the box and be a good reliable piece of test equipment.

Buying from Amazon will be a lottery on this type of device, dubious on quality, safety and documentation.

Buy cheap, buy twice.

Buy a good one, sell it on once finished with…?

I’d not bother unless he’s got a known problem such as massive daytime overvoltage from solar panels or something.

A friend was never able to turn on a Woo tube amp without fireworks on a sunny day without using one.

The age that equipment was made in didn’t have any mains better or worse than now. If something’s gonna blow, it’s gonna blow.

Its about being able to slowly bring up the voltage on equipment. It is common good practice when dealing with older equipment that hasn’t been used for some time. It helps electrolytic capacitors reestablish their dielectric and if there is a fault it minimises the risk of damage.

I bought one from RS, I recall it wasn’t especially expensive.

Another trick, if not quite the same thing as the Variac is to put an incandescent light bulb in series with the live supply. If there is a serious fault it limits the fault current and lights up brightly to tell you there’s an issue!

If they don’t know what they are doing with such equipment, best to give it to someone who does!


With photographic studio flash equipment you can just start it off at it’s lowest power setting then fire it off then increase the power maybe half a stop then fire it off again and carry on increasing the power step by step by small increments until you reach full power.

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