50 Watt LED Light

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When I was ordering power LED’s last October, my son Kubi wanted a power LED to use it as a projector lamp. We ordered 50 Watt 4000 Lumen bright white LED together with a 50 Watt inverter to drive it.

He installed the 50 Watt LED light into Sony Projector Model VPL-HS10, but it turned out that it was not powerful enough. Although it worked fine in low light conditions, the picture was washed out by even a small amount of daylight. So he abandoned the idea, and I got back the 50 Watt LED light from him.

One thing to keep in mind is that although this LED is rated at 50 Watts, it can be used at lower ratings without any problems.

In the end, I decided to use it as a garage door opener light, partly because vibrations caused garage door light bulbs to fail quickly. When I timed the garage door light, I found out that it stays on for about 5 minutes whenever the garage door is opened or closed. This is not bad at all as far as the power consumption goes. But the problem is that the garage door light also comes on whenever somebody walks in or out of the garage while the garage door is open. During the summer months, children go in and out of the garage all day long. A better way would be for the garage door opener to have a light sensor on it such that the light would come on only at night when it is needed, not during daytime.

The picture below shows the power LED mounted on a heat sink. There is a lens super glued on top of the LED light. Kubi had glued the lens on the power LED to focus the light, and I did not remove it in case it is damaged. The lens causes light to focus into about 120 degrees instead of 180 degrees without the lens.

I bought the heat sink from a local metal recycling yard for $2.50. The copper pipes conduct the heat so well that the LED light hardly gets warm even without any fan.

Heat Sink

I did not put a circuit diagram for this project, but it is the same as the one in this post. The only difference is that there is no fan, nor the peltier device, nor the auto lamp. The LED lamp is connected straight across the C2 capacitor. C1 is set to 30 uF, which results in about 30 Watt lamp.


Measuring Light

In the past with LED Light conversion projects, I would try to compare the amount of light produced by making a rough judgement. Finally I broke down and bought a lumen (or lux) meter so that I can compare the project results objectively.

When I tried to measure light, I found out that measuring light is a funny business. Even a slight movement of my body would effect the measured light due to reflections or indirect shades. The location of the meter sensor makes a big difference. But even after adjusting for all of these variables, it seems like the eye itself becomes more sensitive in low light conditions.

For example, when I measured light by the window in a very cloudy day, the reading was over 2000 lux. But at night in the kitchen with all the lights turned on (fairly bright room) showed about 300 lux.

When I measured the original light (60 Watt incandescent) about 5 feet away (at about 45 degree angle from the source), it showed 15 lux. More or less this reading of 15 lux was about the same throughout the garage at 5 feet away. With the LED light, in exactly the same location the lux meter showed 150 lux. But because of the lens, right under the LED lamp, the lux meter showed well over 300 lux. The meter was probably right, because even my wife made a comment that the light was very bright (and for her no light ever is too bright!).

Inverter Destruction

Normally I don’t write about failures, but this one was both so funny and just so bad that I will write about it. Below is the picture of the inverter.


When we first received this inverter, the question was which side is the input and which side is the output. There were no markings of any sort. After putting on our thinking cap on, we figured out the input and the output. But I made a comment to Kubi that the way it was set up did not make any sense to me. As you can see from the picture, one side of the inverter has black and white wires, the other side two red wires.

Color Coding

In the US electrical code, three wires distribute the power inside buildings. One is the grounding wire which is green, or bare copper wire. The white wire is the neutral wire, which is safe to touch. The black wire is the hot wire which represents danger of getting shocked. You have to remember that any color could have been chosen as standard color for these two wires that carry power.

In the DC (Direct Current) world, for example when you open up a PC, the red color represents +5 Volts, the yellow color is typically +12 Volts, and the black color is the ground.

Revisiting the inverter

Months passed and we wanted to use the inverter again with the LED lamp. I had completely forgotten which side was which. So I thought we should be safe and hook the inverter to the varactor so that I can increase the power slowly so that we don’t damage the inverter.

I connected the black and white side to the varactor and gave only about 30 Volts AC (normally 120 VAC). When I turned the power on, Kubi said ‘Hey dad, I smell something burning’. I immediately turned the power off.

Sometimes inverters don’t work too well in low power conditions. So I increased the power to about 60 Volts. I turned on the power just for a second, and a smoke and little light appeared in both the varactor and the inverter. I immediately turned the power off.

I thought maybe this inverter needed full power. I took it into the kitchen where there was an easily accessible plug. Kubi must have known what is coming, because he took cover around the cabinet only the top of his head showing. I barely touched the black and white wires to the plug, and a huge spark and smoke came out of the device and the plug. Yeah, that was exciting.

We then realized that the input was the two red wires and the output was the black and white wires. I think the Chinese were thinking that the two red wires had no polarity and they are the same color, which makes sense. And the black was probably ground, and the white wire was + 30 Volts DC.

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