"jibaro" wrote in message
om...
would this work?
http://www.epanorama.net/documents/ir/irremote.html



Well I haven't analyzed the circuit in depth, but yeah it does look like it
definitely has the right idea. As the text indicates it would probably work
better if it were configured for 50% duty cycle.

Also, AFAIK IR remote controls more often operate with a carrier frequency
of 38kHz rather than 40kHz. Certainly both frequencies along with a few
others are used in IR remote applications, but I think the 38kHz is more
popular. I could be wrong.

Nevertheless since the 555 is a poor tolerance RC type oscillator it would
probably be a good idea to use a small frequency trimming pot to allow
yourself to tweak the frequency over the full range including 38kHz and
40kHz to find the frequency of best performance (and perhaps much wider
range still just in case your IR remote runs at something like 56kHz for
instance).

Also the IR LED driver is pretty wimpy in the schematics. I would replace
the output stage 2N2222 with a small MOSFET and reduce the LED series
resistor substantially. The range will certainly be reduced using it as is.