Can you use two IR transistors and and IR LED to pan a turret?

By any chance are you reffering to laser targeting? To where to point the laser and the turret follows.

Robin2:
What LED? a standard size IR LED

What photo transistor? an standard IR phototransistor

What transistor amplifier? none

What do you mean by "detect"? have an analog output a value different from it's previous value

What ambient light level? typical office lighting or darker

What nearby reflecting surfaces? none

There you go, it's still simple. I just want a response from someone who has already worked on something similar.

HazardsMind:
By any chance are you reffering to laser targeting? To where to point the laser and the turret follows.

nope. Just Just use the balancing of IR phototransistor values to pan a turret toward an IR LED. Really simple stuff. Someone has to have already done this before..

I just want a response from someone who has already worked with these parts.

Which parts?
You haven't specified any parts.

So the turret will center itself?

OK, here's the answer you want to hear: it will work and it will be effective, and you probably don't need a processor to do it.

Now, what are you going to do about seduction by other environmental sources of IR?

AWOL:

I just want a response from someone who has already worked with these parts.

Which parts?
You haven't specified any parts.

You're being unnecessarily picky. The level of detail you're asking for isn't relevant but just so you can get over this mental block, here are parts for you: RadioShack.com Official Site - America's Technology Store They don't matter though because the difference between these parts and other IR phototransistor and IR Leds of the same size is obviously negligible.

AWOL:
OK, here's the answer you want to hear: it will work and it will be effective, and you probably don't need a processor to do it.

Now, what are you going to do about seduction by other environmental sources of IR?

What are the other environmental sources of IR light in an office environment? If they exist, then where is an IR LEd emitter/detector pair that use a spectrum that is not typically found?

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.

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.

AWOL:

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.

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?

unnecessarily clear;

I'm sorry, I don't understand that concept.

unnecessarily picky.

Ditto.

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

The RadioShack "spec" quoted only spectral sensitivity.

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.

David82:
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.

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.

zoomkat:

David82:
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.

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.

So with an LED that was twice as bright, I should get twice the distance.

Have you heard of the inverse square law?

HazardsMind:
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.

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

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?