I picked up a few donwlights of ebay, and would like to dim them using a mosfet and my Uno.
I initially hooked up the driver outputs via a logic level mosfet . I had issues with dimming, as it was very choppy, and the driver was humming/ringing very audibly. I then opened up the driver to have a peek and see if I could directly dim via pwm on the driver.
But it looks like my board consists of a clone of NXP's SSL2115X The labeling on the chip says 61NL-4M7HJ but I am pretty sure it's the SSL215's clone.
I was wondering, if there are any known solutions for these led lamps? I have made some drivers earlier with pwm dimming, but they are dc-dc ones and I would like to do away with the need for a separate transformer/power supply.
Would anyone know of a workaround, without actually dimming the AC signal, but using a ac dimming driver board that are plenty available on ebay, and using a pwm signal from the arduino on that? I could also use an optocoupler to get some isolation if need be. Any suggestions?
PS: On snooping around, I see that this isn't new and uncommon) Maybe I should ask dc42 for inputs if I get none here!
It looks like that constant current drive is not designed to be dimed.
If you think about it PWM chops up the supply and a constant current tries to maintain it. So the two systems are fighting each other.
Grumpy_Mike:
It looks like that constant current drive is not designed to be dimed.
If you think about it PWM chops up the supply and a constant current tries to maintain it. So the two systems are fighting each other.
Yep, I figured that out after looking at the datasheet, which leads me to the second part of the question, if they are some known chips/boards that can accept PWM dimming.
Would you know of any 220v AC driver boards that could be modified? I did some digging around and found quite a few DC boards that use the PT4115 that has accepts PWM signals to dim it.
I do have a slightly more powerful 50w board that is based on the OB330. But would appreciate some pointers on a ~300mA AC driver board that can be modified to work with an arduino to dim without having to play with the AC signal.
LED drivers for mains AC, with dimming, tend to be rare and overly expensive. I think you'll find it much less expensive to use a DC wall wart and then use DC LED drivers like those based on the PT4115.
Whether the PT4115 is a good solution depends to a degree on how many LEDs are in your downlights. Usual wall warts have 5v 9V or 12V output voltage. If your downlights have 1-3 LEDs connected in series you should be fine.
The PT4551 needs a minimum supply voltage of 6V and max of 30V.
You can get 4 and 6 channel shields. The 4 channel is OK with Uno. For the 6 channel you need a Mega.
If you stick with the single channel driver I would actually toss the Uno and use a Teensy LC. Much smaller, much cheaper and much more powerful than An Uno. Not that you need all that power for the dimming a few LEDs but the smaller and cheaper may do it.
The Teensy LC also as many more PWM pins that can dim up to 16 bits and not just 8 like most Arduinos.
