IR Receiver Thingy

Thread Starter

Chris15

Joined Apr 15, 2009
252
Hi
You know those Infrared receivers that have 3 legs and are a small black box. How do i male a switch circuit out of it? i know how to make a relay switch with a LDR but how do i switch a relay on and off with an IR receiver and an IR LED?

Please help i am puzzled

Chris
 

BMorse

Joined Sep 26, 2009
2,675
Possibly, the "thingy" is a phototransistor. You might see a number on it and look up a data sheet.

If it is, this thread might be interesting - http://forum.allaboutcircuits.com/showthread.php?t=19076
Actually it is an IR integrated circuit, with demodulator and comparator built in.....

In the picture you can see a typical block diagram of such an IR receiver. Everything is built into one single electronic component.
The received IR signal is picked up by the IR detection diode on the left side of the diagram. This signal is amplified and limited by the first 2 stages. The limiter acts as an AGC circuit to get a constant pulse level, regardless of the distance to the handset.
As you can see only the AC signal is sent to the Band Pass Filter. The Band Pass Filter is tuned to the modulation frequency of the handset unit. Common frequencies range from 30kHz to 60kHz in consumer electronics.
The next stages are a detector, integrator and comparator. The purpose of these three blocks is to detect the presence of the modulation frequency. If this modulation frequency is present the output of the comparator will be pulled low.


My .02
 

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BMorse

Joined Sep 26, 2009
2,675
Hi
You know those Infrared receivers that have 3 legs and are a small black box. How do i male a switch circuit out of it? i know how to make a relay switch with a LDR but how do i switch a relay on and off with an IR receiver and an IR LED?

Please help i am puzzled

Chris

It would probably be better to use a uc to receive the IR signals from a remote to control a relay or any other output, that way you wont get erronious signals turning your relay on or off.....

My .02
 
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