please help me build a simple and SMALL ir detector

[aforme]

hi,

I'm hoping people in this forum can help me with making a simple and small (light) infrared detector.

first, I know nothing about electronics or circuits. So please treat me like an elementary school student when you explain things.

What i'd like to do is use an infrared diode to detect infrared light, and output about 5 volts upon detection (5-10 is ok). For my purposes size is a big factor. i need something tiny and light.

please tell me:

1) what supplies i need (including images would be great, but i can google image them anyway)
2) how exactly to connect everything -- (solder the end of this to the end of that etc)

most of the sites i've looked at contain circuit diagrams. this is partially helpful, but since i don't know the meaning of most of the stuff in the diagrams, it's not really helpful.
really basic step by step instructions would be very appreciated (as well as explanations about what each part does as i'm curious, but can survive without it)

thanks,

-a

 

[ericgibbs]

hi,
This would be a good starting point.

https://www.electro-tech-online.com/content/61-laser-ir-beam-alarm-system.html

 

[MikeMl]

Under what sort of ambient lighting conditions (sunlight, indoors)?
What is the range you want it to operate?
How much power can you pour into the transmitter?

 

[aforme]

Under what sort of ambient lighting conditions (sunlight, indoors)?
What is the range you want it to operate?
How much power can you pour into the transmitter?

the range can be pretty short. i think 15 cm would be the shortest though. possibly 30 cm, but i think 15-20 would work.

I'm not sure about the power because i'm not sure how this gets set up. If you're talking about power for the IR LED (transmitter, emitter?), then any amount of power is possible. If the receiving end needs power, then 3-4 volts is the max. Basically, the ir diode for the detection, the voltage output, and everything in between need to be on an animal's head. if power is necessary, no big batteries, but a few watch batteries would be ok. the LED will be above the cage, and can be connected to any power.

the lighting is one light bulb, don't have specs with me now. I think it's incandescent, but it might be florescent. this all takes place in a cube type box that is less than 2 feet on a side.

 

[MikeMl]

Ok, the question about ambient lighting has to do what the IR receiver sees in addition to the IR beam you are creating yourself. The sun and incandescents flood the poor IR receiver with a steady signal, so even to get 15 to 30cm range reliably, you will have to use an AC-coupled amplifier and detector for a 1/0 indication that the IR is present or not. The best bet is to use one of the integrated IR receiver modules like the TSOP1738 or GP1U58Y.

Most IR detectors have integrated lenses which mean that the receiver is quite directional. Can you keep the receiver more-or-less aimed at the transmitter?

 

[aforme]

Ok, the question about ambient lighting has to do what the IR receiver sees in addition to the IR beam you are creating yourself. The sun and incandescents flood the poor IR receiver with a steady signal, so even to get 15 to 30cm range reliably, you will have to use an AC-coupled amplifier and detector for a 1/0 indication that the IR is present or not. The best bet is to use one of the integrated IR receiver modules like the TSOP1738 or GP1U58Y.

just to be sure, something like the TSOP1738 includes both the detector and an amplifier. So in fact, it would be the only thing needed on the receiving end? when i looked on other sites, many mentioned needing an op amp (not sure what that is). but it seems that what you recommend already includes one? that would be ideal

would florescent or white LED light be better?

Most IR detectors have integrated lenses which mean that the receiver is quite directional. Can you keep the receiver more-or-less aimed at the transmitter?

well, i think more-or-less is the best i can do. how directional is quite directional? the cage i'm using is about one foot on each side, slightly shorter in height. i can attach the transmitter to the top. if multiple transmitters is a good idea, i can place a few around the sides too. unless having signals come from more than one place will cause a problem.

 

[aforme]

Ok, the question about ambient lighting has to do what the IR receiver sees in addition to the IR beam you are creating yourself. The sun and incandescents flood the poor IR receiver with a steady signal, so even to get 15 to 30cm range reliably, you will have to use an AC-coupled amplifier and detector for a 1/0 indication that the IR is present or not. The best bet is to use one of the integrated IR receiver modules like the TSOP1738 or GP1U58Y.

just to be sure, something like the TSOP1738 includes both the detector and an amplifier. So in fact, it would be the only thing needed on the receiving end? when i looked on other sites, many mentioned needing an op amp (not sure what that is). but it seems that what you recommend already includes one? that would be ideal

would florescent or white LED light be better?

Most IR detectors have integrated lenses which mean that the receiver is quite directional. Can you keep the receiver more-or-less aimed at the transmitter?

well, i think more-or-less is the best i can do. how directional is quite directional? the cage i'm using is about one foot on each side, slightly shorter in height. i can attach the transmitter to the top. if multiple transmitters is a good idea, i can place a few around the sides too. unless having signals come from more than one place will cause a problem.

 

[MikeMl]

Here is the directivity of the TSOP17xx right off the data sheet. Looks like it is usable +-70deg from the vertical

 

[aforme]

Here is the directivity of the TSOP17xx right off the data sheet. Looks like it is usable +-70deg from the vertical

thanks, that should work fine then
was i right about not needing anything else besides the TSOP1738 and an infrared source to get the 5V?

-a

 

[MikeMl]

It is more complicated: You need to build a transmitter circuit which chops the IR source LED (about 50:50 duty cycle) at the same frequency as the receiver is rated for, say 40KhZ. This can be a 555 circuit as long as it is operated from a regulated voltage so that its frequency is stable.

When the receiver locks on to the IR signal, its output pin will be low as long as the 40kHz IR signal is present. If the 40kHz IR signal is interrupted, either by being shut off electrically, or by being blocked by an IR opaque object (your hand in the beam), the receiver output pin will go high, and then back low. The time it stays high tracks the interruption of the beam if that interruption is short (<a few hundred ms), or if the beam is interrupted longer, the output will go back low by itself after a few hundred ms even if the beam is still obstructed.

If you need a longer output pulse, that will take more circuitry.

 

[aforme]

It is more complicated: You need to build a transmitter circuit which chops the IR source LED (about 50:50 duty cycle) at the same frequency as the receiver is rated for, say 40KhZ. This can be a 555 circuit as long as it is operated from a regulated voltage so that its frequency is stable.

When the receiver locks on to the IR signal, its output pin will be low as long as the 40kHz IR signal is present. If the 40kHz IR signal is interrupted, either by being shut off electrically, or by being blocked by an IR opaque object (your hand in the beam), the receiver output pin will go high, and then back low. The time it stays high tracks the interruption of the beam if that interruption is short (<a few hundred ms), or if the beam is interrupted longer, the output will go back low by itself after a few hundred ms even if the beam is still obstructed.

If you need a longer output pulse, that will take more circuitry.

that was a bit confusing. sorry, but like i said, i know next to nothing about circuits and electronics. Are you saying a IR LED source just by itself will not work?

If my emitter signal was actually a series of pulses, say 20 pulses at a 10-20 Hz, with a pulse duration of 5 msec, would the voltage output follow the pulses? if my output were controlling an LED, would it be able to create the same signal? basically i need a series of IR pulses to precisely control a blue LED to make a series of pulses with the same timing.

however, i am looking through a catalog, and wonder if you can tell me if this item will also work. SFH5110-36 or 38

the metal prongs on these are pretty long. can they be cut really short without ruining the ability to output the voltage?

lastly, there are 3 prongs on these. one if the output, one is the ground, but i don't know what i would connect the 3rd one to.

thanks,

a