IR Transmitter and Receiver

[UTMonkey]

If I pulse an infra-red LED at around lets say 5khz and point it at a PhotoTransistor (Infrared), would I be correct in saying

1. The distance between the RX and TX can be further apart because of the pulsing?
2. To stop other frequencies I would need some kind of filter?

Would I take the signal from the transistor:

• Run it through a highpass filter letting signals at 4.5khz and above pass, then

• Run it through a lowpass filter letting signals 4.5khz and below pass

• Until what I am left with is my signal?

Am I on the right track?

 

[blueroomelectronics]

Much easier to use an off the shelf 38KHz IR decoder, a 555 can modulate an IR LED to 38KHz easy.

 

[Darth Bagel]

You'll want to widen the passband a bit, no?

 

[audioguru]

An IR receiver IC has a bandpass filter at its 38kHz frequency, not a lowpass and a highpass that affect each other and attenuate the signal.
It has a light blocking black coating that passes IR.
It has automatic gain control of its very high gain amplifier so it isn't overloaded by compact fluorescent light bulbs that flicker at 38kHz.

 

[UTMonkey]

Looks like a nice bit of kit, Thanks.

 

[Nigel Goodwin]

Looks like a nice bit of kit, Thanks.

You can nick them out of any old TV or VCR, they all work pretty well the same - just make a note of the connections though, they aren't all in the same order!.