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Topic: Infrared Receivers and Transmitters? (Read 2042 times) previous topic - next topic

polishdude20

So do all IR receivers have that square type of casing around them or can they also looks just like regular LED's?

How would I differentiate between a receiver and a transmitter?

RuggedCircuits

Quote
So do all IR receivers have that square type of casing around them or can they also looks just like regular LED's?


They probably do not look like regular LED's. You have to distinguish between an "IR logic decoder" and a much simpler "IR photodiode" or "IR phototransistor". An IR logic decoder (like the TSOP4838) has an IR photodiode inside it, plus a whole bunch of additional circuitry to pulse a logic output low when infrared energy is detected at a specific frequency (38 kHz). It also generally has 3 pins because it needs 2 power pins (e.g., +5V and 0V) in addition to its logic output.

The simpler IR photodiode/transistor are just passive devices; they aren't sensitive to any particular frequency, they don't have any additional circuitry, and they only have 2 pins. You definitely want the "IR logic decoder" if you're going to be decoding infrared remote controls.

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The Aussie Shield: breakout all 28 pins to quick-connect terminals

polishdude20


Quote
So do all IR receivers have that square type of casing around them or can they also looks just like regular LED's?


They probably do not look like regular LED's. You have to distinguish between an "IR logic decoder" and a much simpler "IR photodiode" or "IR phototransistor". An IR logic decoder (like the TSOP4838) has an IR photodiode inside it, plus a whole bunch of additional circuitry to pulse a logic output low when infrared energy is detected at a specific frequency (38 kHz). It also generally has 3 pins because it needs 2 power pins (e.g., +5V and 0V) in addition to its logic output.

The simpler IR photodiode/transistor are just passive devices; they aren't sensitive to any particular frequency, they don't have any additional circuitry, and they only have 2 pins. You definitely want the "IR logic decoder" if you're going to be decoding infrared remote controls.

--
The Aussie Shield: breakout all 28 pins to quick-connect terminals



could the IR logic decoder be taken out of a VCR player or a common DVD player?

Magician

Yes. It will provide digital output without a decoding.

polishdude20


Yes. It will provide digital output without a decoding.



wait so if I take out an IR receiver with 3 pins from a dvd player or vcr then it wont be good for what im doing?

Schmidtn

Is it my turn?

So, what are you doing?

polishdude20


Is it my turn?

So, what are you doing?


I want to copy an IR signal to the arduino EEPROM and then transmit it back through an IR transmitter.

Schmidtn

Ah, I see.  Why did you make two posts about this, it's kind of confusing.

A 38kHz Infrared Receiver Module from RadioShack is around 4 bucks and will work.
http://www.radioshack.com/product/index.jsp?productId=2049727

I'm not sure if a 38K module from an old TV or DVD player will work, but if you've already salvaged one and it is not working you might try to see if there is a filter over the lens.  Taking that off might get your module working but it will also open you up to false readings.  Best bet is just to get a new 38K IR module.

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