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From: al@psivax.UUCP (Al Schwartz)
Newsgroups: net.video
Subject: Re: Infrared remotes
Message-ID: <930@psivax.UUCP>
Date: Wed, 8-Jan-86 16:08:28 EST
Article-I.D.: psivax.930
Posted: Wed Jan  8 16:08:28 1986
Date-Received: Sat, 11-Jan-86 07:48:28 EST
References: <2453@ukma.UUCP>
Reply-To: al@psivax.UUCP (Al Schwartz)
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 32

In article <2453@ukma.UUCP> edward@ukma.UUCP (Edward C. Bennett) writes:
>       Can someone out there give a simple explaination of how infrared
>remote controls work? How hard would it be to build your own? Is there
>a "programmable, one unit imitates anything" one of these on the market?
>(Hmmmm, new product idea....)
>       My cable decoder, TV and VCR all have infrared remote and I think
>it would be fun to build something capable of controlling all three.
>ihnp4!cbosgd!ukma!edward

Infrared remotes (the transmitter) send pulses of infrared light (using an
infrared LED) to the device to be controlled (the receiver).  For each
command that is sent to the device, there are a stream of pulses that
constitute a unique bit pattern.  The receiver knows the format of this
pulse stream and can then decode the command.  Usually the pulses of light
vary in duration to distiguish the 1 and 0 bits.  The pulses of light are
usually sent at some modulation frequency such as 40Khz to minimize the
effects of ambient room light.

General Instrument (a semiconductor manufacturer) makes IC's that make the
transmitter (AY-3-8470) and the receiver (AY-3-8475) designs as simple and
inexpensive as possible.  My bet is that most of the remotes use these chips
or some equivalent.

General Electric has just introduced a general purpose IR remote that will
mimic the function of all of your other IR remotes.  The selling price here
in LA is $150.  I think this was a very good idea.
are a stream of pulses organized in a predetermined format such that the
--
                  Al Schwartz
                  Pacesetter Systems, Inc.,  Sylmar, CA
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