I had Halogen bulb lights 12V 20W. If I replaced with LED light 3W bulb, do I need to change the transformer?


I had Halogen bulb lights 12V 20W. If I replaced with LED light 3W bulb, do I need to change the transformer as well? Or it will just work as it is?

Current Transformer max capcity: 120W total (12V)

No. As long as the voltage output of the transformer is not significantly higher than 12 volts, like more than ~18 volts, it should be safe to operate them. This can happen when a transformer is intended to operate a higher-current device, where that higher current draw causes the voltage to drop to ~12 volts. With less current demand from the LEDs, the transformer’s output voltage will rise higher than 12 V.

The bulb should specify the absolute maximum voltage it can tolerate.

Also, be sure that they can be operated on 12 VAC, many can only operate on 12 VDC. They need to have extra diodes in them to run on AC.

Not necessarily – the bulb will still work on the old transformer if it is a GU5.3 12v lamp. Be aware though, that 12v LEDs tend to flicker on several types of transformer. It is usually a better idea to remove the transformer completely and fit a 240v light fitting with a 240v LED 3W lamp (known as a GU10). By all means try fitting a 12v LED and see how bad the flicker is. I personally never bother with them and prefer to fit 240v ones instead.

Also bear in mind that if you have a dimmer switch, you will need both a dimmable LED lamp and a suitable dimmer switch (such as a Varilight trailing edge push dimmer).

20w 12v Halogen Bulb

Some smart transformers or powers supplies have protection circuits to shut them down when the bulbs blow.
As the LEDS will only draw a small current you may get the same effect.

Bulbs work on AC, some LEDs need a DC supply, (the LED has a + or red mark on one pin) If your LEDs have the mark then don’t use them.

Try it and see!

It the “transformer” is a transformer then you will not need to change it, if it is a solid state power supply then it could go either way.

I’m guessing a 120w supply is probably a transformer.

If you have a solid state style power supply, and you are feeding multiple fixtures, and leds don’t work then you can usually use just one resistive bulb and it will take care of the problem.

Hi guys,
i have 12v 20w Clear Halogen Light Bulbs, i have attached image can i connect it directly to 12v dc output, i have 12v converter which i brought for stereo..
please advise

thanks & regards
Shardanand

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