24VDC LED on 24VAC power source. Amateur questions.

DavidAlan1062

Sep 22, 2022
7
What is the simplest circuit I can use to hook up a 24VDC 3 watt LED ribbon to a 24VAC 20VA power source? I used a 3K resister to dim the LED and stop the flicker is this sufficient? Will it shorten the life of the LED? Or do I need a bridge rectifier or something? And how should it be wired?
Thank you.

Martaine2005

May 12, 2015
4,355
You certainly can use a bridge rectifier. But maybe a single diode will also suffice.
Wire in series with one of the AC wires. Or a bridge will have AC and DC written on it. Usually the inner two are AC and outer two DC with + and - labelled.

Martin

bertus

Moderator
Nov 8, 2019
2,731
Hello,

As @Martaine2005 said, a bridge rectifier would do the trick.
You have the flat ones and box ones.
These are common pinouts for them:

Bertus

Attachments

• GBU60X.pdf
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• kbpc50 series.pdf
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DavidAlan1062

Sep 22, 2022
7
Thank you so much for your help.
To dim the brightness of the LED should I put the resistor on the - side of the led or + side?

bertus

Moderator
Nov 8, 2019
2,731
Hello,

In a series circuit the order of parts does not matter.
The resistor can be used on both sides.

Bertus

DavidAlan1062

Sep 22, 2022
7
Can you recommend a resister for this purpose so I get the right one? And what are the different values I go by to dim it more or less?
Thank you,

bertus

Moderator
Nov 8, 2019
2,731
Hello,

Do you have a datasheet of the used led?
That way we can see what is needed.

Bertus

DavidAlan1062

Sep 22, 2022
7
Hello,

This is what I have.

David

DavidAlan1062

Sep 22, 2022
7
This is what it looks like.

Attachments

• COB LED 2.jpg
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bertus

Moderator
Nov 8, 2019
2,731
Hello,

When you take 0.4 meter if the strip it will take 11.52 X 0.4 = 4.6 watts.
The max current will be 4.6 Watts / 24 Volts = 0.192 A
As the strip seems to have current limiting build in, you could reduce the voltage by putting some diodes in series in stead of a resistor.

Bertus

DavidAlan1062

Sep 22, 2022
7
Hello,

Thank you for that. But I don't know about diodes. Sorry I don't know much at all about electronics.
Do you have a name and part number?

David

bertus

Moderator
Nov 8, 2019
2,731
Hello,

Diodes of the type 1N4001 to 1N4007 will do the trick.
Those can handle currents upto 1 Amp.

Bertus

Attachments

• 1N400X.pdf
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DavidAlan1062

Sep 22, 2022
7
Thank you very much Bertus.

David

Sunnysky

Jul 15, 2016
529
What do you want to compromise with simplicity? max brightness, flicker? fully dimmable. Because you must learn how to follow directions and get a few more parts than diodes, capacitor and a pot will burnout as a dimmer with 200 mA.

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