24V 850mA AC-AC adaptor needed - any idea where?

I was wondering if anyone knows where I can get hold of a 24V 850mA power supply adaptor - it's for a set of decorative lights as my original adaptor has broken.

I don't know the faintest thing about electronics, so I don't know where to look for one. I'm in the UK.

If anyone could help, I'd be most grateful. Thank you.

Reply to
metaphorng
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Easiest option is probably somewhere like Maplin.

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    Dave Plowman        dave@davenoise.co.uk           London SW
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Reply to
Dave Plowman (News)

I've just taken a look but there's nothing suitable - they're all 12V or AC/DC, whereas I need 24v AC/AC.

Thanks all the same.

Reply to
metaphorng

They probably don't exist as a universal wall adaptor at that voltage, at least I've never seen one. If you have any paperwork for the lights you could look for an address or phone number and try the manufacturer. Failing that, have a look at your local car boot sale, people often dump old AC adaptors into a box of junk and sell them off for a few pence, you might get lucky.

You need to get one of the same voltage and the same or higher current. I have a 24v one I use to power a home built battery charger, and IIRC it's off an old document scanner.

As a last resort, if the lights are really valuable to you, you might find a local hobbyist who is prepared to knock together a power supply, but it likely won't be the cheapest option.

There's not many parts needed for an AC-AC power supply. A 240V-24V transformer from Maplin or RS etc, a case to mount it in, mains cable, LV cable and a few sundry items. It's technically straightforward enough, even for a beginner, but I would never recommend a mains powered project for a total newbie, it's too dangerous.

Dave

Dave

Reply to
Dave D

So long as you're just running incandescent lights you can use AC/DC, it won't make a difference.

What's wrong with the original unit? Sometimes a momentary short will blow an internal fuse that can be replaced.

Reply to
James Sweet

That depends . I have a set of novelty lights which have a control box, and the lights are switched using small triacs. If I was to power them off DC the triacs would latch on all the time.

Dave

Reply to
Dave D

Nothing lost if it's broken by opening up the wall wart and seeing if it's just a transformer inside. If so, Maplin etc might have one that fits.

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    Dave Plowman        dave@davenoise.co.uk           London SW
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Reply to
Dave Plowman (News)

True, I was thinking these were just simply lights.

That said, I've modified 12VDC wall warts to put out AC for a couple of novelty lamps that had 12v syncronous motors in them. The wall warts were the rare type held together with screws so it was a simple matter to remove the rectifier/filter board and replace it with a fuse.

Reply to
James Sweet

What about using two 12VAC Wallwarts and wiring the two outputs in series. Measure the outputs, if you get 0 volts then just swap the output wires of one as the AC is out of phase and cancelling each other out.

Wes.

Reply to
Wes.

At least on this side of the pond (i.e. US), 24V is very common for furnace controls, so transformers producing that voltage are available at most hardware stores.

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Reply to
CJT

Furnaces I've seen all have internal transformers, but 24v wall warts are indeed very common for security systems, and I've seen a few doorbells that used them instead of permanently wired in units. IIRC UK doorbells don't use 24v though.

Reply to
James Sweet

CPC Preston.. Website.. Google for CPC

Ron(UK)

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Reply to
Ron(UK)

Thanks for the responses everyone.

I've looked around the CPC website, but am completely lost. I've put '24V AC' in the search box but there are 82 results. If it doesn't say 'DC', is it automatically AC-AC? How do I know what wattage I need - it doesn't say on my original adaptor.

All I know is I need a 24V AC-AC 850mA power supply/mains adaptor, but as I don't know anything about elctronics, the whole list on the CPC site just bamboozles me.

Cheers.

Reply to
metaphorng

That's easy. Multiply the voltage by the current to get the wattage. 24 x

0.85 = 20.4 Watts.

However, you don't want to run it flat out, a 25 Watt or 30 Watt adaptor would be good.

I think you're flogging a dead horse to be honest. 25 Watt, 24V AC wall adaptors aren't exactly a common generic item I'm afraid. You may find one eventually, at a price, but I can't think of any reason a manufacturer would make a 'universal' 24 V AC adaptor, no demand you see. Most equipment designed to run off aftermarket adapters requires DC at 12V or below.

Your best bet, if you don't have the manufacturer's details for your lights, might be to find a piece of equipment which uses a similar adapter, ie a similar light set, and ordering a replacement from the manufacturer.

Can you tell us something about the lights? ie are they electronically sequenced from a control box? Are they Christmas style lights or something else?

Dave

Reply to
Dave D

They're like Christmas tree lights - i.e. in a sequence, but they don't flash or anything, they're just either on or off (if that makes sense).

Reply to
metaphorng

I just had a look and I only see AC output transformers up to 500mA, if your device draws more than that then you'll need a bigger capacity adapter.

Reply to
James Sweet

Odd that they use a transformer, all our miniature Christmas lights are in series directly off the mains. Anyway it sounds like a DC output power supply would work just fine, if you'd like to find out before you buy one, connect the light string to the battery in your car, if it lights up dimly then they work fine on DC.

Reply to
James Sweet

*Very* common here in Europe, James. The EU has very strict regulations on electrical safety, and a very sizable amount of low power 'novelty' lighting is LV nowadays.

Dave

Reply to
Dave D

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