Re: one channel radio frequency help

Gary Tait wrote:

"robot guy" <huntin4jesus@xxxxxxxxx> wrote in
news:1175634612.259231.224850 @p77g2000hsh.googlegroups.com:

Only problem is that the I don't know what was causing the device to
only respond to a certaing rate of speed from the flashing led. It was
all pre manufactured into a little sugur cube sized box

You had, likely, a typical IR reciever module from a VCR os the like. The
simply detect the presence of an IR signal oscillating at around 40 Khz,
and activate (pull to ground) the output pin at the presence of the 40Khz
IR signal. Your 555 was blinking the IR LED at the set frequency for that
module. A typical IR remote would modulate that carrier by turning it on
and off in the data pattern the remote creates.

RF remotes are similar, in that instead of a 40 Kz carrier on an IR LED,
the data pattern is directly modulates the transmitter. In theory, you
could do the the same, by gating an RF carrier, and detecting its
presence, but that is less than ideal. You should encode it, and depending
on the application, you should have a self error checking code.
If you can bother you can find chips that do both the transmit and receive
functions for IR or RF remotes. They are typically marketed in transmit -
receive pairs. There are usually inexpensive ceramic resonators to
generate master clock frequencies for both parts.
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.  
--Schiller
.

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