Hello All;
This is my first post, and I want to jump right in with a problem regarding LED lighting to replace all the 110VAC lights in my house. I'm starting with the home theater, and I need the help because in my theater, I want all the lights to be dimmable so I can see the movie in partial darkness.
Background: I have 5 separate circuits in my theater now. On each circuit there are 6 pot lights in the ceiling, currently running 50 watt halogen GU-10 type bulbs. So each circuit is consuming around 300 watts.
Halogens dim nicely, but they give off a lot of waste heat, and they tend to blow more often than I would have guessed. I want to replace all the lights in my house with dimmable LEDs, starting with the theater. The goal is to save money, since my little monsters leave lights on all over the place, and also to never have to replace another light bulb again.
I bought 2 LED bulbs from Ebay, made in China. They are the GU-10 type, rated at 3 watts of consumption, and each have 72 LEDs soldered in place. They were advertised as dimmable with a "normal" dimmer, which nowadays means a Triac-based PWM dimmer from Home Depot.
The problem is that they don't dim as expected. I put one LED bulb in place of a halogen, left 3 other halogens in the circuit and switched it on. The LED did nothing until I slowly turned up the dim setting to about half way, then POP, on it came, almost full intensity. I was able to back off a bit and dim it more evenly, but the dimming knob was very sensitive. Almost no movement of the knob, and a big change in light output from the LED bulb.
I just popped one bulb open today to have a look at the internal circuit. I discovered 4 diodes in a bridge (no surprise) 2 capacitors, 3 resistors, and the fact that the 72 LEDs are arranged in two parallel banks of 36. Each bank of LEDs is made up of all 36 LEDS connected in series (one long chain). This surprised me a bit, although I wasn't sure what I'd find.
I guess the LEDs are all sharing 110 volts divided by 36, or about 3 VAC each. I could easily be wrong about this, but it looks that way.
So, here it is: Why isn't it dimming as advertised? How can I fix this, assuming that I want nice even dimming of the LED bulbs?
I also have read about LED drivers. These apparently, are the items to control LED dimming, but they are also PWM circuits. I know all PWM circuits are not created equal, but why wouldn't this work with a cheapie Home Depot PWM dimmer?
Thanks, and any help from this forum would be greatly appreciated.
Cheers, Tom Kay, Ottawa Canada.
This is my first post, and I want to jump right in with a problem regarding LED lighting to replace all the 110VAC lights in my house. I'm starting with the home theater, and I need the help because in my theater, I want all the lights to be dimmable so I can see the movie in partial darkness.
Background: I have 5 separate circuits in my theater now. On each circuit there are 6 pot lights in the ceiling, currently running 50 watt halogen GU-10 type bulbs. So each circuit is consuming around 300 watts.
Halogens dim nicely, but they give off a lot of waste heat, and they tend to blow more often than I would have guessed. I want to replace all the lights in my house with dimmable LEDs, starting with the theater. The goal is to save money, since my little monsters leave lights on all over the place, and also to never have to replace another light bulb again.
I bought 2 LED bulbs from Ebay, made in China. They are the GU-10 type, rated at 3 watts of consumption, and each have 72 LEDs soldered in place. They were advertised as dimmable with a "normal" dimmer, which nowadays means a Triac-based PWM dimmer from Home Depot.
The problem is that they don't dim as expected. I put one LED bulb in place of a halogen, left 3 other halogens in the circuit and switched it on. The LED did nothing until I slowly turned up the dim setting to about half way, then POP, on it came, almost full intensity. I was able to back off a bit and dim it more evenly, but the dimming knob was very sensitive. Almost no movement of the knob, and a big change in light output from the LED bulb.
I just popped one bulb open today to have a look at the internal circuit. I discovered 4 diodes in a bridge (no surprise) 2 capacitors, 3 resistors, and the fact that the 72 LEDs are arranged in two parallel banks of 36. Each bank of LEDs is made up of all 36 LEDS connected in series (one long chain). This surprised me a bit, although I wasn't sure what I'd find.
I guess the LEDs are all sharing 110 volts divided by 36, or about 3 VAC each. I could easily be wrong about this, but it looks that way.
So, here it is: Why isn't it dimming as advertised? How can I fix this, assuming that I want nice even dimming of the LED bulbs?
I also have read about LED drivers. These apparently, are the items to control LED dimming, but they are also PWM circuits. I know all PWM circuits are not created equal, but why wouldn't this work with a cheapie Home Depot PWM dimmer?
Thanks, and any help from this forum would be greatly appreciated.
Cheers, Tom Kay, Ottawa Canada.