🚀 go-pugleaf

Matthew A. Skala (ua123@freenet.victoria.bc.ca) wrote:
: 
: 
: Many thanks to all who sent me info on IR remote controls for VCRs. 
: Here's a summary of the information I got:
: 
: brianr@tekig1.pen.tek.com (Brian Rhodefer) says that Radio Shack makes an
: IR receiver module that could be used - it contains a phototransistor,
: tuned amplifier, and demodulator that operates at 40 kHz.
: 
: bbs.haymore@tsoft.net (Ed Haymore) says that his friend was experimenting
: with this sort of thing and most VCRs used a carrier frequency of about 38
: kHz, digital on-off-keying modulation.
: 
: jmorriso@ee.ubc.ca (John Paul Morrison) says that most VCRs use digital
: pulses of 40 kHz carrier.
: 
: So based on this information, it sounds like a frequency of 40 kHz is
: pretty standard as a carrier.  So what I plan to do is use a 567 tone
: decoder to demodulate the signal,
Forget this and use the Sharp I/R demodulator from radio shack.
They cost USD$3.50. 
they only have 3 pins to connect. +5v, Ground, TTL data out.
Before I found these modules I had a hard time getting any kind of range out
of my demodulator.
the module I tested had better range than any of my equipment with remotes.
I you can't get these modules I can send you some if you like.

: 555 to modulate, when sampling just
: time-stamp the edges of the modulation and play that back into the 555 at
: 40 kHz.  This is very short-range, so it doesn't matter if the transmit
: frequency is a bit off and is just on the edge of the VCR receiver's passband.
: 
Marc Christensen