Thread: Red LED lights jack's tool shed

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Hello all! So I saw everyone was ordering these LED lights from Jack's tool shed. So I jumped on the wagon and ordered red and green. The green ones are AWESOME! Anyone else having trouble with the red ones? They are just NOT very bright at all.

I just got my white and green ones, they should work for a little accent lighting. Having something so small and with a clip was a huge seller for me.

I bought 4 of the red ones along with 4 each of the blue,white,and green ones and only 1 of the red ones is left. The other 3 either didn't work or burned out.........The others work fine.

I'm trying to wire the red ones into a DC power supply and they overheat the resistors while the blue ones do not. The voltage for them is "wrong" somehow, that would also explain why the batteries don't last long in them. I'm going to try to drop it to 4.2v at 20mA (was doing 4.3v at 40mA before). I don't see any resistors on the board inside but there /has/ to be something because 4.5v (3 button cells) is not a standard LED voltage. Even assuming the buttons don't give out full power (3.8-4.2v) it's still way too high for a red LED and would burn it out if it wasn't altered. The white ones also seem to dull fast on batteries but I haven't even tried wiring those yet.

wow, that seems like a lot of work for a 99 cent light. Like I said the green ones are perfect. I think I'm going to send the red ones back and get more green ones. I'm only planning on having them used for this weekend anyways. SO if they last through the weekend then no harm done. Thanks for the input!

Yeah if you look at the specs of the LEDs the different colors actually have different requirements. They are not all the same so what you are saying makes sense.

Here are some great sites that actually talk about this:

http://www.oksolar.com/led/led_color_chart.htm

http://www.gizmology.net/LEDs.htm

Originally Posted by Xane

I'm trying to wire the red ones into a DC power supply and they overheat the resistors while the blue ones do not.

You need a custom resistor for each color type, this is why you are overheating the red ones as these are the most different from the blue ones. If you use the link from lostskelton you will see that reds and blue have a vastly different forward voltages so the resistive load needed to make these work is different.

Blue:
4.5V - 3.6V = 0.9V
0.9V/.020A = 45 ohms

Red:
4.5V - 2.0V = 2.5V
2.5V/.020A = 125 ohms

Put a Red in a Blue Setup
4.5V - 2.0V = 2.5V
2.5V/45ohms = .056 A
You are forcing more than twice the current into the red using the blue resistor thus it overheats.

exactly! If you attach a LED to a power supply and move through the voltages step by step and you will see that you will start off dim, then progressively get brighter then become dim. You want to be in the spot where your LED is the brightest and not overload them and dim them while burning them out. I think this is probably the most common misconception about LEDs.. more power doesn't equal brighter light.

I know - the point here being that these pre-made LED clip-on lights are all designed to work with 3x 1.5v coin cell batteries, so theoretically they're already properly wired with resistors. There has to be a resistor in the red one because even if you take into account that button cells don't always put out 1.5v continuously, even if it only comes out to 4v, that's still way too much voltage for the red LEDs.

The only answer would be that there's enough resistance soldered into these things to prevent the red LED from instantly frying, but it's still not enough, whereas the blue ones are fine. They probably use the same resistor board for all of these so it's probably giving out 3.6v.