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I am working on a project and got stuck on a point, and I hope somebody will guide me. I have a hardware device which has different color LEDs (green, red and yellow) and I have to calculate how many times each color LED glows for each mode of operation.

The LEDs that are connected to the device are pretty small and will blink only for a couple of seconds, ao I am looking for a very sensitive light sensor.

So what kind of light sensor do I have to use with Arduino UNO to achieve this?

Should I go for BH1750 or do you have any other suggestion?

Thanks in advance.

  • You don't need something that advanced. Simple LDRs or Phototransistors will do just fine. Just make sure you add some back tape, so no outside light can come into the sensors, as that will make it a lot easier for you. Just attach the sensors to the analog pins, with appropriate resistors. – Gerben Jun 29 '15 at 15:46
  • @Gerben, I think you should add that as an answer. It is what I would use, too. – AMADANON Inc. Jun 29 '15 at 20:56
  • Thank you so much for your suggestion Garben , I will try to use Simple LDR , will you be able to suggest any specific model name related LDR's, So i that i can go and buy those particularly. – ferraro Jun 30 '15 at 15:57
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Like the OP wrote, you can use very simple sensors, like a phototransistor. Even simpler, if you can somehow isolate each pair LED-phototransistor, you don't even need to care about the color of the led, just use some bluetac to stick one phototransistor on top of each LED and only measure the brightness.

edit:

A quick check on ebay shows the 3DU5C as good candidate: it has a metallic container, so it is more directional than one with full plastic body.

3DU5C ebay link and datasheet

It is shown to have a peak response at 880nm (red light), so you might not be able to use it directly as digital input for the other 2 colors you want to monitor and instead have to treat it as analog reading.

OTOH if you use them all as analog inputs, you will not have to add the resistor that would be required for binary mode.

  • Thank you so much for your suggestion Igor , I will try to use Simple LDR , will you be able to suggest any specific model name related LDR's, So i that i can go and buy those particularly. – ferraro Jun 30 '15 at 15:57

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