Hi folks,
I have a question relating to using equipment rated at 220 - 230 volts in the UK. Anyone aware of a transformer for 250 step down to 230 volts, maybe a couple of hundred watts rating? It is not for power amps so I’m not concerned about current limiting that the big amps folks are, and I don’t need isolation so an auto transformer would do. Also, re generators, although the ideal solution are way way out of my price range. Anyone? Many thanks in advance.
(Yes, I now know that UK is theoretically 230 volts (as is the rest of EU now), but it was a fudge - they widened the tolerances so no one actually had to change their supply grid).
Now I know elsewhere on this page the usage of 230 volt rated equipment has been suspected of causing more issues in the UK than it would in EU, I’m just looking for a solution (that doesn’t cost as much as a DS DAC!) for my equipment, which, being, er, at the cheaper end of the market, does not really have much headroom in its PSU.
Answers obtained from other forums (fora?) in case anyone else wants the info in the future:
A variac (which is the obvioius answer that I should have thought of)
An auto transformer made up from a standard mains transformer, ignoring the secondary (one that has 240 and 220 volt taps) - at one’s own risk of course).
An auto transformer made up of the primary and secondaries of a transformer (there’s a YouTube video on this one, I intend to review and consider if it is crazy or not!).
Interesting that many many folks simply stated “it’s fine” or “UK mains is now rated at 230 volt” (have they never measured their mains?)
…but a few others agreed they have had problems with kit intended for EU voltage (220 volts) running on high 240 volt and failing.
The history is that the EU commission (or whomever makes these decisions) decided that we should harmonise with mainland Europe, so our 240 volts and their 220 volts became 230 volts everywhere.
only they simply widened the tolerances permissible, so no one had to change their power grid.
So now anything really voltage sensitive is more likely to fail in the UK if not made with lots of leeway (which tends to be the case on cheaper gear).
I would give full marks for lateral thinking for that solution and, apart from the very remote possibility of the insulation on the secondary being inadequate for mains voltages, cannot see why it would not work. I have only used a borrowed Variac 45 years ago, when testing home designed linear power supplies for resistance to brown-outs, and it hummed.
The only item I have ever owned which was sensitive to the change from 240 to 220V mains was a Solartron valve oscilloscope from the 60’s. It had jumpers at the rear to set it for a range of supply voltages in 10V increments. Once set for 220V it worked fine when back in the UK.
It would be more interesting to do as well.
Hadn’t considered the acoustic hum of a variac, my only encounters with one involved very loud guitar amps, so that wasn’t a concern, thanks for the heads up
What was most intriguing about the autoTX suggestion was that a 200VA tx was used to make a 2000 VA auto, on the principle that the current was mostly traversing the secondary windings at the “top” of the tx, which of course is much higher current rated than the primary. That’s the bit I need to think through and maybe test, it seems plausible though and the 200VA tx in the YouTube video seemed quite happy with an electric kettle running on it.
Interesting stuff anyway
On lower end kit manufacturered to tight budgets for EU market it can take PSU capacitors outside the range they are happy with. Leads to many more failures.
In a similar way to hard drives (for example) that will go forever if run at 30 celcius but fail in 2 years when run at 40 celcius - this I have observed many times.
I had a suspicion this would be a similar case, and have had this confirmed by several folks online. Yes if the kit concerned had better PSU it wouldn’t be a problem, but this kit does not, like most equipment outside the luxury audiophile catagory it is built to a tight budget.
I have some ideas now, and will report back if I don’t zap myself out of existence connecting transformers in unconventional ways
I have a fatherly interest in TPA3116 based amp kits. The maximum voltage for such an amp is 24V. Some modules are fitted with 25V smoothing capacitors, and they often fail. Others use 35V units and give no trouble. So much grief just to save a few yen!
So the auto tfmr using primary and secondary of a normal tx - I guess it will need a proper case though.
30VA tx but seems happy running around 100 watts of 220 volt kit
Only wrinkle was getting the secondary windings connected the right phase 'round as they were not colour coded.
Job’s a good 'un as they say around here, now I can sleep better knowing my PSU caps are safe(er).
Thanks to Chris for helping me accept the autoTX concept!
Proof (for me) is that the back of the SRCs are now gently warm to the touch where internal regulators are screwed to it for heat dissipation whereas previously they were too hot to touch.
I may even be able to remove the shonky fan I have pointng at the back of them too which can only be a good thing.
A story should have an end, so here it is, just needs the lid screwing down.
Wooden front panel as I can’t make 22mm holes in the 8mm thick chunk of aluminum the case came with (some other time maybe with a drill and file).
I’ve observed voltage changes from 248 volts to 232 on the input already today, as the neighborhood cooks their Sunday lunch…
