Questions about Infrared sensor

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FuneralHomeJanitor

Joined Oct 12, 2019
34
Hey everyone I just have a few quick and probably dumb questions regarding using an infrared sensor, because it seems like I can’t find much useful information about the actual working of this kind of component.

I am referring to the 3 terminal kind of IR sensor package with the metal around the photodiode. Ibought some cheapo components a while back and the datasheet was in Chinese. I can’t seem to find any info on how to actually do calculations. I understand it is tuned to 38 kHz.

I want to know how I can draw the circuit and do basic calculations to arrive at an expected output voltage.

I have messed around a little by connecting a resistor to the output pin with the resistor’s other terminal connected to ground with an oscilloscope probe connected across the resistor. I see there is a constant DC voltage and if I push my tv remote buttons I see digital modulation causing that dc voltage to be pulled low, but don’t know how to calculate what that DC voltage will be. I was thinking of it like a diode but the 3 terminals are confusing me.

Is the output pin supposed to be a current or voltage? I know someone can draw this in a simple circuit so if someone can please post it with an explanation I would appreciate it. I don’t have the information about the component itself but I did my best to describe this package, and know someone must know what I am referring to! Thanks in advance!
 

MrChips

Joined Oct 2, 2009
23,516

Audioguru again

Joined Oct 21, 2019
3,173
It is too bad that you bought a cheap Chinese copy of a good IR sensor. Maybe the good datasheet of a TSOP1138 or TSOP1738 is similar to the Chinese one or you can buy the good IR sensor.
 

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atferrari

Joined Jan 6, 2004
4,322
Hey everyone I just have a few quick and probably dumb questions regarding using an infrared sensor, because it seems like I can’t find much useful information about the actual working of this kind of component.

I am referring to the 3 terminal kind of IR sensor package with the metal around the photodiode. Ibought some cheapo components a while back and the datasheet was in Chinese. I can’t seem to find any info on how to actually do calculations. I understand it is tuned to 38 kHz.

I want to know how I can draw the circuit and do basic calculations to arrive at an expected output voltage.

I have messed around a little by connecting a resistor to the output pin with the resistor’s other terminal connected to ground with an oscilloscope probe connected across the resistor. I see there is a constant DC voltage and if I push my tv remote buttons I see digital modulation causing that dc voltage to be pulled low, but don’t know how to calculate what that DC voltage will be. I was thinking of it like a diode but the 3 terminals are confusing me.

Is the output pin supposed to be a current or voltage? I know someone can draw this in a simple circuit so if someone can please post it with an explanation I would appreciate it. I don’t have the information about the component itself but I did my best to describe this package, and know someone must know what I am referring to! Thanks in advance!
Test your output with a PULL UP resistor (4K7 ?)

IIRC all decoders use a pullup resistor.
 

DickCappels

Joined Aug 21, 2008
7,426
Here is a cheap Chinese IR receiver and its datasheet for US 6¢ each in quantities of 10 and up. They are supplied through regular authorized distributors.
http://www.es.co.th/detail.asp?Prod=004800024

The datasheet has just enough English on it to allow you understand some aspects of the device.

There is noting wrong with cheap Chinese components provided you understand what you are getting and they are backed by a reputable distributor.
 
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