Superimposing a 38kHz wave

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tanky321

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555 38khz

Im working on a IR-RF-IR transmitter, for a tv remote.

I took it with me to school and took some screen shots of the remote output, they're below. Its a 3Vpp PWM wave with a 1Vpp 38kHz signal riding on top of it.

On the transmitter end I'm gonna use an op-amp to cut off the 38kHz, il transmit the square wave, then reapply the 38kHz.

So my questions are:
I was thinking about using a 555 to generate the 38kHz, good idea? If not any help as to what would work?

How would I go about superimposing that wave???



Thanks,

Andrew

 

rc5 38khz

The remote can be expected to use RC5 or one of the other less popular protocols. You may want to study the respective internet documents. Apart from the 38 kHz carrier (which could be generated e.g. by a 555), it involves a command sequence coded in the baseband pulses. It's not actually a square wave. Most people use a dedicated remote control chip or a µP (e.g. a PIC) to generate the carrier and the command sequence in one part. But if you're following a very basic approach, you can design the remote controller from CMOS logic IC.
 

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    tanky321

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38khz pic remote

Do you have any suggestions for an dedicated remote control IC? This is all I can seem to find.

https://www.infraredremote.com/RS117.htm


Its pretty much a custom application, and I only need 10-12 buttons maximum.


Thanks!

Andrew
 

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