IR Detector

Step 8 Test your creation

You are all done!!! Test you creation!

Take any remote. Put you fototransistor close to the IR LED of the remote. Push the switch,hold it, and push any button on the TV remote,hold it. The LED on the detector should start blinking.

IR light is not visible by a naked eye but you can see it whit a camera also! (picture 3)

Comments

[Norikaeru]

I got a detector out of a a vcr that was being thrown away and when the switch is pressed the led lights up and stays that way with or without any tv remote, could the ir transistor be broken to just let current flow?

[Hycro]

I once had a stereo that if I were to hold the switch on my halogen bed lamp close enough to the on position that it would make the light flash, I could make my stereo open/close the CD drawer, or even change the volume, depending on how close or far the contacts of the switch were apart.

[comodore]

That is very interesting, I never heard something like that, but I can bet you there is a scientific explanation for it! Hmm, interesting, tell that to teck-king, he might have an explanation....

[Goodhart]

I wonder if one of the LED's isn't "detecting" the signal? That can happen, but normally only if there is a voltage already applied to the circuit.

[Arduino Guy]

possibly the halogen lamp emits a flickering ir signal (all heat consists of ir rays)from the mains 60Hz/50Hz and then the device gets "confused"?

[Hycro]

Sounds very likely...I didn't know then what I know now about that kind of stuff, though it's marginally more now...XD

[Hycro]

Oh likely, but it was still neat to do. I think the stereo that did it was the one I also blew the amp in...

[comodore]

Haha! How did you do that? :)

[Hycro]

I had so many speakers connected in parallel that the resistance went below the amp's tolerance, and since it was under warranty, I didn't take it apart to see exactly what happened, but it likely overheated, and probably didn't have an automatic thermal shut-down, I tried it the next day, and still didn't work. It was designed to use a 6 ohm speaker per channel, and I had 6 or 7 8 ohm speakers connected in parallel, thereby reducing the resistance, essentially shorting the amp, or even overheating it. That's another reason why I like the amplifier ICs for car stereos, they have internal short and thermal overload protection, and operate at anywhere from 11VDC to 18VDC without damage, though the manufacturer states the optimum performance is usually at ~13.4VDC to ~15VDC. (Manufacturer states that is the standard charging voltage for a lead-acid battery being charged by the alternator in the car.)

[comodore]

Well, I am a n00b in electronic, meaning I started to learn it not while ago..I understan, I think I do, what happened, it probably overheated, it was just too much for the amp to take... But, I know that in newer devices, by the IC, or a transistor, they put a thermoresistor, NTC, I think it is.... So if it gets over heated the resistance value rises and like a switch, cuts of the circuit...or a thermal switch.... :)

[Hycro]

Yea, most car stereo amplifier chips that I've researched have that capability.

[phevtron]

ok but whats the range? can be used to switch lights etc?

[Goodhart]

If you used a relay it might be possible.

[bestboy5408]

 Ÿý= =

[comodore]

?

[anil yadav]

actually i made one ir detector by reading your instruction but it is not working so pl ans my few question?
is the blinking of led can be seen by naked eyes ?
actually i tried to test but the led doesnt blink so is there is any other way to test the ir detector?

[izidor7]

I actually can see a red like light... but, it is visable only in a darker place... toher technik..

Take your cell phone and watch through the camera... you'll see the lila light on the screen!!!!! 

[amitdas]

your led must be damaged..coz i tried n its working perfectly...

[comodore]

You point your IR LED from your remote to your Phototransistor on your device that you made and you press any button on the remote while holding the push switch on your IR detector that you built (in case you have a switch like i do)
The led, in my case a red one, should start to blink as the IR led on your remote does, accept you can only see the blinking led on your detector, not the IR led on your remote.
Make sure that you wired everything up correctly, make sure the LED pins are as they should be placed!
Also make sure that your remote is working! You can use a standard camera or your phone camera, point it at the IR LED on your remote and see if, when you press any button the LED blinks.
Are you sure that you got a Phototransistor and not some other component, they look just like LEDs in some cases, in my case also!

Check all this and get back to me when you have some news or more questions!

[w477s]

Hi, can i use reversed IR led diode instead of IR phototransistor?

[Smokedasphalt]

yeah, you can...!

[ryguy425425]

so is that just an IR diode wired backwards? Instead of waiting for a response I think ill just go ahead and try it...

[Smokedasphalt]

Oh, I thought he meant an IR photodiode. An IR led wired backwards won't work.

[w477s]

ir photodiode != ir led diode? holly crap -.-

[ryguy425425]

Too late! good think I have 20.

[w477s]

o_Ops! xD i have about 40 of them :S

[bigstiffy]

A IR led wired backwards will actually work, at least it did for my circuit (although I used a different schematic). Here's the schematic I used if you're interested: carlitoscontraptions.com/2007/09/ir-detector/

[geeklord]

so if you took out the IR LED in a remote, hooked it up in a circiut with a 3V source, and a switch, and pressed the switch on and off in binary code, you could potentially control any IR device as long as you knew what the code was?????I am so smart......:D

[uberdum05]

In theory, you could. But in reality, your finger would have to touch the button 38,000 times per bit ! Or, just set up a 555 timer to do the 38Khz part

[kadris3]

at 3 vdc you might want less resistance. try 47 ohms(40 calculated). IR leds have a much lower forward voltage than all other LEDs. one batt(1.5vdc)might work if only left on for a short while. usually IR has a 1.2 vdc forward voltage or about that. also a phototransistor has 3 leads. there is no connection to the base. u can do the same w a photodiode which only has 2 leads.

[S1L3N7 SWAT]

No, unless you can tap out binary code ridiculously fast. Your remote sends out the pulses rather quickly, so you probably wouldn't be able to do it your self, it needs a microcontroller and what not to work.

[geeklord]

But in theory, you could if you or something else could tap it out

[natman3400]

In theory yes, yes you could tap it out.

[Arduino Guy]

you can use an arduino or pic microcontroller of something similar(eg; seeduino, lilypad, freeduino...) and program it to send codes, this instructable,http://www.instructables.com/id/Fart-Operated-Random-Channel-TV-Remote/, helps a bit (Whithout the fart sensor) or http://www.arcfn.com/search/label/arduino also's ok. but, for this you need intermediate programming knowlege and one of the devices listed above. anything else is probably futile.

[farhan77]

that was a neat instructable! what i was wondering, was that what is the range of this phototransistor? what i had in mind was to hook up a small low voltage relay instead of using an LED. With this simple circuit i can use relay where i want a PUSH Switch kinda functionality. But that depends on the range of the circuit! any idea how long with this fototransistor will detect a general remote control beam(signals, pulses) :)

[comodore]

Well depends... 1. On the type, quantity and quality of the phototransistor 2. And the the same thing goes to IR LEDs You can make this with lets say 3 Phototransistors and make a simple push button circuit that powers up 4 IR LEDs... You can make something like my Film Canister LED Flashlight, just insted of the white LEDs you put IR LEDs... I think that would work, I am not shore on witch distance, I would say about maybe 2-2,5 meters, maybe... If you decide to make one of these, I would be glad to help you! Please feel free to ask questions if you have any! Cheers!

[neardood]

that poor indicator LED looks a bit strained, maby you should add a more powerful resistor??? If not, the LED will eventualy die, as it is when u leave it on it'l get hot.

[kadris3]

if the battery were new and the forward voltage of the IR LED is 1.2vdc then 390 ohms is needed. with the battery @ about 7.2vdc the 300 ohms is the correct figure. simple circuit that works: good instructable

[comodore]

Actually the 9V battery is almost dead so that is the reason why the LED is faid.

[RGM La Paz]

so this can control your tv sorry its that im a curious year old and i just started learning this cool stuff