Power supply adaptor

carlbhoy

I need to buy a power adaptor for some Christmas lights, I believe it has to be something like 5Vdc 1.5VA, the only ones I can find is a 3 pin 5V power adaptor 2A AC-DC, could anyone tell me if this would be safe to use for what I need, many thanks

forgotmyname

Something like.... ??

So does the power supply need to limit the voltage/current or do the lights have voltage/current limiting built in?

Get it wrong and you get a super bright light show for a split second then a funny burning smell and a string of dead lights or worse.

kwikbreaks

It would probably be cheaper to buy new lights. If you insist on a new psu then get the details of what is needed from the old one. Keep to the same voltage. Ensure dc or ac specifications match. Ensure power output (amps) as big or bigger than old psu.

If you don't have the old psu throw the lights away because there is huge variation between different types.

DoaM

I agree with both replies above - if you're not sure, don't risk it.

If you know the make/model of the lights then you could post it here and someone may be able to recommend a replacement PSU. But the safest route is to get replacement lights.

System

The voltage must be the same although with things like lights you can get away with +/-10%. if it was DC output it must also be DC output. The amperage has to be at least the same as the original one but can be more and it doesn't matter how much more. You could use a 5V, 500 million amp power supply if you could find one. The PSU cannot force current into a device, the device will only draw what it needs.

almillar

If they're well enough labelled, surely we can achieve the right the right settings with something like this:
https://www.amazon.co.uk/ZOZOTMUniversal-Regulated-Switching-Replacement-Electronic/dp/B017OMEW4Q/ref=sr_1_3?ie=UTF8&qid=1543928599&sr=8-3&keywords=universal+dc+adaptor


Not sure about the connector obviously.

DoaM

Tarambor wrote: »

You could use a 5V, 500 million amp power supply if you could find one. The PSU cannot force current into a device, the device will only draw what it needs.

True ... but if a short occurred then you'd have up to 500 million amps driving through the short without any limiting from the PSU, making a seriously impressive heater!

forgotmyname

DoaM wrote: »

True ... but if a short occurred then you'd have up to 500 million amps driving through the short without any limiting from the PSU, making a seriously impressive heater!

Or in the case of LEDs they draw 10watts when the old supply limited the output to 1watt?

Superbright lights for about 3 seconds when it all goes black with a crispy smell

System

forgotmyname wrote: »

Or in the case of LEDs they draw 10watts when the old supply limited the output to 1watt?

Nope. It is standard design practice to have a current limiting resistor with every LED, whether external or built into the LED itself.

ukcarper

Forgive if I'm missing something but isn't the current and therefore power determined by voltage and resistance of load so without a fault the lights will draw same current no matter what currant the power supply can supply.

Owain_Moneysaver

Some LED lights (probably less likely christmas lights, but LED strip and similar) need a constant current power supply, rather than constant voltage.