Dimming LED bulbs

[orezok]

I know that some LED bulbs are dimmable, but not all. This year for the first time ever, we bought an artificial tree. The preinstalled LED bulbs are far too bright. First I tried a 120v LED dimmer switch with no joy. Next I tried a DC PWM dimmer and no luck again.

Any suggestions?

 

[quicksandfarmer]

Spray the lights with glass frosting spray paint.

The LED element itself requires a very small voltage, around 1.2V. The circuitry in it is to take whatever you send it and drop it to that level. Look at the voltage rating on an LED device, it's typically quite wide, like 100-277 volts. The way that dimming is typically implemented is that there is circuitry to detect that it's running on a dimmer, and if so it turns off some of the LED elements. If you device doesn't have dimming circuitry it's only going to run full on or full off.

 

[orezok]

Spray the lights with glass frosting spray paint.

The LED element itself requires a very small voltage, around 1.2V. The circuitry in it is to take whatever you send it and drop it to that level. Look at the voltage rating on an LED device, it's typically quite wide, like 100-277 volts. The way that dimming is typically implemented is that there is circuitry to detect that it's running on a dimmer, and if so it turns off some of the LED elements. If you device doesn't have dimming circuitry it's only going to run full on or full off.

A couple of things. First, there are 700 embedded lights on the tree. Not gonna be able to spray them. The voltage to the LED's is transformed down to about 30v DC.

 

[Mendonsy]

Is it powered by one of those "brick" power supplies that you plug into the wall outlet? If it is there should be some information about the voltage output stamped on the power supply. It is most likely to be a switching power supply so changing the input voltage won't help. It will either make 30 volts or nothing.
If it is running at 30vdc now, reducing the power supply output by a couple of volts should do it. You might be able to find a different "brick" with a lower DC voltage. My personal choice would be to use an industrial 24vdc supply (usually adjustable from about 18 to 30 volts) to power it.

 

[RNeumann]

Is it powered by one of those "brick" power supplies that you plug into the wall outlet? If it is there should be some information about the voltage output stamped on the power supply. It is most likely to be a switching power supply so changing the input voltage won't help. It will either make 30 volts or nothing.
If it is running at 30vdc now, reducing the power supply output by a couple of volts should do it. You might be able to find a different "brick" with a lower DC voltage. My personal choice would be to use an industrial 24vdc supply (usually adjustable from about 18 to 30 volts) to power it.

This is the only thing that may work. The LED power supplies aren’t standard but hopefully everything is done in the power supply (not at the bulb). If that’s the case, a different power supply would do the trick.
Remember the output now could be something “different” like a very high frequency dc. They are decreasing brightness and heat by pulsing the power. So if it’s say 30vdc out but pulsed now a 15vdc power supply that doesn’t pulse at the same frequency won’t be half as bright.

 

[Mendonsy]

This is the only thing that may work. The LED power supplies aren’t standard but hopefully everything is done in the power supply (not at the bulb). If that’s the case, a different power supply would do the trick.
Remember the output now could be something “different” like a very high frequency dc. They are decreasing brightness and heat by pulsing the power. So if it’s say 30vdc out but pulsed now a 15vdc power supply that doesn’t pulse at the same frequency won’t be half as bright.

Yeah, those LED supplies are a different animal, mostly PWM (constant current) instead of constant voltage. I do deal with one supplier that has LED supplies so if orezok can come up with some specs for what he has I might be able to find something that will work.

 

[orezok]

Here ya go.

 

[Mendonsy]

OK, I think this one might work to solve your problem, but I suggest that you call TRC to see what they think. They have good tech support.
HLG-4H-36B - MEAN WELL - TRC Electronics

 

[newbury]

I know that some LED bulbs are dimmable, but not all. This year for the first time ever, we bought an artificial tree. The preinstalled LED bulbs are far too bright. First I tried a 120v LED dimmer switch with no joy. Next I tried a DC PWM dimmer and no luck again.

Any suggestions?

Go buy another tree and chalk it up to education.
Didn't it say any place that they were not "dimmable"?

Most of the LED's I buy say on the package if they can be used with a dimmer.

 

[RNeumann]

Not sure your level of comfort with electrical but you can cut the power supply out of the circuit and hook up your battery charger to the the two wires. If you have a choice go for a non-automatic type. The battery charger will put out about 14v. Knowing that you should be able to size an appropriate power supply- either more or less voltage.
If that sounds too risky to you I’d go for a variable voltage output power supply so it can be dimmed.