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Author Topic: Can you use two IR transistors and and IR LED to pan a turret?  (Read 1717 times)
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What are the other environmental sources of IR light in an office environment?
Well, it's a 150 million kilometres away, but it's a biggie.

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If they exist, then where is an IR LEd emitter/detector pair that use a spectrum that is not typically found?
Illuminators used for IR number plate recognition systems are necessarily heavily filtered to eliminate environmental IR.
Come one man. This is indoor only. I know the sun would totally mess it up. The things you're referring to are all outdoor issues. Let me be even more unnecessarily clear; In a gigantic, building sized box, with fluorescent lights, how far away can a slowly blinking IR led be to register a change in value on the IR receiver as it blinks on and off?
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I don't think you connected the grounds, Dave.
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unnecessarily clear;
I'm sorry, I don't understand that concept.

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unnecessarily picky.
Ditto.

It's taken fifteen replies to get even a quarter decent statement of requirements.

The RadioShack "spec" quoted only spectral sensitivity.
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You aren't going to know the answer to the question unless you've experimented with a similar project. Trying to speculate without the necessary experience is a waste of both of our time.
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You aren't going to know the answer to the question unless you've experimented with a similar project. Trying to speculate without the necessary experience is a waste of both of our time.

I agree. Better you waste your time than mine, but that being said, the farthest I can get from my tv line of sight is 33', and my IR remote still works.
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You aren't going to know the answer to the question unless you've experimented with a similar project.
I have.
I used some very large area detectors, optical filters and a modulated source.
Mostly analogue electronics (747 op-amps).
The answer? Around 6 metres, to within about 10 degrees, which was good enough, but the slew rate of the servos was the main limiting factor.

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You aren't going to know the answer to the question unless you've experimented with a similar project. Trying to speculate without the necessary experience is a waste of both of our time.

I agree. Better you waste your time than mine, but that being said, the farthest I can get from my tv line of sight is 33', and my IR remote still works.
That's actually a really good example. So with an LED that was twice as bright, I should get twice the distance.
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Ok let's think this through. You have two photoresistors focusing on one source, and you want the turret to line up with that source, correct. Regardless of what's on the turret, you want to make it so the turret is pointing directly at the source.

Well, being that you will be receiving readings from the photoresistors, in order to find the center of the two, you will need to compare the two readings and turn accordingly.

If that is the case, it is extremely simple to do. If that's not the case, then your not clearly explaining what you want to do.
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So with an LED that was twice as bright, I should get twice the distance.
Have you heard of the inverse square law?
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Ok let's think this through. You have two photoresistors focusing on one source, and you want the turret to line up with that source, correct. Regardless of what's on the turret, you want to make it so the turret is pointing directly at the source.

Well, being that you will be receiving readings from the photoresistors, in order to find the center of the two, you will need to compare the two readings and turn accordingly.

If that is the case, it is extremely simple to do. If that's not the case, then your not clearly explaining what you want to do.
yea, that's all I'm trying to do. I want to know how far away the IR LED will be detected though. If I can't make it work at 100ft or so, then it's not worth pursuing.
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If I can't make it work at 100ft or so, then it's not worth pursuing.

Go big.

http://www.ebay.com/itm/Infrared-IR-LED-illuminator-Board-Plate-for-CCTV-Security-Camera-w-36-Light-/171023517936?pt=US_Surveillance_Accessories&hash=item27d1cbc8f0
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What I'm asking about is essentially the same thing as a sun tracker.



except it will need to follow an IR LED or small cluster of LEDs and be much faster on the response time. I know the servo can move much faster but maybe there is something else limiting the speed like the response time of the phototransistor. Do any of you with experience with this stuff think that it will be able to work with those modifications?
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Why not buy a couple of phototransistors and an LED for £1 or £2 (and a cheap digital multimeter if you don't have one) and do some experiments. If you gave that as much time as people have spent trying to explain the complexity of the problem you would have an answer by now - good or bad.

Then you could inform us.

...R
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