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what LED to use? Answered

Hi there,
What kind of LED can I use to activate a phototransistor based switch for a (3 - 5) merters distance ?
The phototransistor will be placed in a (2-3) cm long black tube, the whole thing could be installed indoors (shower) or  outdoors (beach).
Also, should I worry about the steam blocking the light in the shower?

Thanks!

Discussions

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-max-

3 years ago

Would a laser diode work? It is highly directional, that may or may not be an issue. You may use a IR led, and a IR filter on the receiver, like a standard IR remote configuration.

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Control80-max-

Answer 3 years ago

Thanks, but the thing is that I will have a set of phototransistors in the other side detecting the signal from the LED's or LD's. The light beams should be parallel, wouldn't there be an interference in the signals if I use an IR LED's?

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Wired_MistControl80

Answer 3 years ago

I'd give it a try !

Even a Laser beam can transmit Data like a IR-Led. (Think NASA) Just be sure that you try it with a few spare IR receivers kicking around in case the Laser burns it out while you test the system. If it does damage the Receiver then try a "Laser Led" it will focus the light better and shouldn't cause any Burn Out problems :)

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steveastrouk

3 years ago

If you have lots of ambient light, you need to use a scheme where you modulate the led at a few Khz, and detect that specific frequency at the other end.

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Downunder35m

3 years ago

For that distance you need a well focussed LED, preferably IR.