How To Test IR Detector ?

aljamri · May 16, 2011

Hi,

Trying to enter IR world I've ordered and received Infrared diode and detector from my regular supplier:

Futurlec, The Electronic Components and Semiconductor Superstore

I tried to get more information about them by typing their numbers INF5940 and INFD5940 but failed to get any other than this. I conclude that the number itself gives the only two piece of information that its 5mm in size and 940nm in range.

Tried to connect them as normal LED ( with clear plastic cap ) practice gave partial success, since the LED when connected with 330 Ohm in series across a 5v supply, gave me a current of 10.83mA and using my camera saw the light bright as in my remote control.

Encouraged by the result I've connected the detector ( with Black plastic cap ) in series with another 330 Ohm across the same 5v supply and measured 11.68 mA current.

Tried to figure wither the detector works or not I've faced both of them together and measured the voltage across the detector. I put a cardboard in between and tried to move it many time to restrict the beam of IR ( if I'm not wrong ) while measuring the voltage across the detector leads which stays 0.87v regardless my cardboard movement.

Is the way I'm testing the detector is correct or not?

Thanks

dougy83 · May 16, 2011

If it's a phototransistor or photodiode, which is likely, then you've got it the wrong way around. They have to be reverse-biased to work as you'd expect. Also, 4k7 might be closer to the desired pullup value (depending on what you want to do with it) - although 330R is fine for your initial testing.

audioguru · May 16, 2011

Why not buy Name-Brand parts that have a datasheet? Nobody (www.datasheetarchive.com) knows anything about the cheap junk you have.

upand_at_them · May 16, 2011

Connect one pin of the phototransistor to ground and the other to a 10K resistor that's tied to 5V. The signal is then read from the phototransistor (not the ground end of course). If this doesn't work then the phototransistor is backwards.

Mr RB · May 17, 2011

I would suggest you buy a integrated IR sensor (3 pin type) or pull one from any old junk TV or VCR. These output a logic level 0v or 5v if the IR signal is present and are more suitable for making simple IR controllers (especially if you want to transmit or receive IR codes later).

dpj · May 17, 2011

Vcc--Res 330 -- IR Diode Anode ---IR Diode Cathode --Micro

Vcc
|
Res 6.8k
|
|-- Micro
|
IR Transistor Collector
|
IR Transistor Emitter
|
GND

Transmitter Section: A low pulse of micro will force IR Diode to emit.
Receiver Section: A IR detected signal will force micro pin to go low.

This works perfectly for me..

aljamri · May 17, 2011

dougy83 said:
They have to be reverse-biased to work as you'd expect..

I've reveresed the detector and got no results.

dougy83 said:
Also, 4k7 might be closer to the desired pullup value (depending on what you want to do with it) - although 330R is fine for your initial testing.

adjusted my decade boxt resistor to 4k7 in series witht the detector, and the only difference is the voltage across the detector canged into 3.0v instead of 0.87v in the early setting.

Thanks for your help

aljamri · May 17, 2011

audioguru said:
Why not buy Name-Brand parts that have a datasheet? Nobody (www.datasheetarchive.com) knows anything about the cheap junk you have.

If I’m staying in Canada, of course! Or in its south neighbor, I’ll be lucky to get whatever I want. Unfortunately, I've said this many time, not every supplier is sending components to my country as simple as yours. I’m dealing with this company that charges me $5 for each order, waits for one month to recive and that’s what they got.

So that, this is one more occasion that you have to thank god that you are staying in Canada, of course!

Thanks AG.

dougy83 · May 17, 2011

aljamri said:
I've reveresed the detector and got no results.

No results? The voltage across the device should be more than you measured before (with it forward biased), and decrease if you point an IR source at it.

dpj · May 17, 2011

Kindly post your the schematic AG.

audioguru · May 17, 2011

dpj said:
Kindly post your the schematic AG.

There are many Vishay TSOP... IR receiver ICs used and are available almost everywhere. They have a very far range and work very well.

Mr RB · May 17, 2011

He's already ignored that suggestion...

aljamri · May 18, 2011

dougy83 said:
No results? The voltage across the device should be more than you measured before (with it forward biased), and decrease if you point an IR source at it.

Soooooooory, I was excpecting to get high difference as if it is normal diode. I've got around 1.5 volts difference whith the reciver reveres biased.

Thanks for your help

aljamri · May 18, 2011

Mr RB said:
I would suggest you buy a integrated IR sensor (3 pin type) or pull one from any old junk TV or VCR..

I've picked one from my junk in an old mouse and enjoyed testing IR. but when connected it using wires to check its max range, got only about 5cm respose in voltage difference.

Thanks

aljamri · May 18, 2011

audioguru said:
There are many Vishay TSOP... IR receiver ICs used and are available almost everywhere. They have a very far range and work very well.

As usual your help is informative. I was strugelling with pin confeguration in one detector I've picked from an old Fuji Seimins mouse. I've figured that the middle is 5v but the other two pins are changing when the wheel is moved, and they have exactly simillar voltage in each case.

audioguru · May 18, 2011

The remote control circuit in a TV uses a TSOP... IR receiver IC so that its range is 15m or more.
An optical mouse does not use an IR receiver IC, it uses a photo-transistor or photo-diode with a range of a few mm.
The difference in range is more than 1000 times.

aljamri · May 18, 2011

So, my target now is to remove one from my faulty Satellite Receiver and test its operation. I'll inform you with the progress. I'll do it tomorrow but now it's my bedtime. Thanks for all .
Baaaaaaaay

audioguru · May 18, 2011

As I showed in the block diagram of a TSOP... IR receiver IC, it is fairly complicated.
It has a high gain amplifier and it uses automatic-gain-control to be less sensitive when there is interference. Normally IR data (bursts and pauses of 38kHz) is sent so the gain is maximum. When the IR 38kHz carrier is continuous like from a compact fluorescent light bulb then the gain is decreased. The IR must not be continuous.

The datasheet recommends the length of each burst of 38kHz (or the frequency the IR receiver is designed for) and the recommended pause between each burst.

You are working blindly since you don't know the details of the IR detectors you find.

aljamri · May 19, 2011

good news. I found IR reciver from an old Satellite Receiver. In shape it looks like AG post (TSOP17..) but nothing written on it. The pin cofiguration also matches. Connected and found working fine along with its remote control. I tried to get working with my IR LED (sender) but gave me very poor distance. Anyway, I'm very happy and I'll start doing some project in my minde using IR remote control.

Thanks for all who helped my especially in this thread, and in general all ETO colleagues.

Thanks for all

aljamri · May 19, 2011

know I understand that the IR reciver has to be more than simple IR transistor. It has to be an IC to combine all the required function including the IR transistor, comparator, filter and modulator.

On the other hand, is the IR sender also more than just the IR LED, because I reduced the series resistor connected eith my IR LED until got 35mA of current flow, but the response from the reciver is exactly the same and it detect it only when it is about 3 mm away.

Is that because of my LED quality as AG indicated? or anything else.

Thanks.

How To Test IR Detector ?

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