[sci.electronics] Help with infrared remote circuit

colonbon@boulder.Colorado.EDU (Glenn T. Colon-Bonet) (04/21/89)

Howdy,
    I recently purchased a VCR and I would like to be able to use the
'power' button on the remote to turn on the TV as well as the VCR.
Unfortunately, the VCR doesn't have a switched AC outlet, as I would
have liked.  I would like to build a circuit to do this, but I'm not
sure which approach to use.  I'm considering:
  1. open up the VCR and find a switched output which could be used to
     drive a relay for the switched AC circuit
  2. build an external infrared detector which will recognize the 'power'
     button sequence and switch the AC output on/off.
I would prefer option 2, mostly because it sounds like the most fun to build,
and doesn't require voiding the warranty!

   I would like to know if anyone has worked with infrared remotes and
knows what kind of protocols are used, is it asynch with start/stop pulses
and some kind of encoding for the keys on the remote?  Also, I am not
sure of how to go about amplifying the signal detected, I presume, 
from an infrared photodiode detector.  I realize that different manufacturers
use different encoding methods, but I'm curious about the techniques
used in general, and what is required to receive them.  I'd appreciate
any help anyone can give me.

			Thanks in advance,
			-Glenn

+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
Glenn T. Colon-Bonet			colonbon@boulder.colorado.edu
University of Colorado at Boulder	...!boulder!colonbon
Boulder, CO 80309			(303) 492-1133
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
Glenn T. Colon-Bonet			colonbon@boulder.colorado.edu
University of Colorado at Boulder	...!boulder!colonbon
Boulder, CO 80309			(303) 492-1133

psfales@ihlpb.ATT.COM (Peter Fales) (04/21/89)

In article <8255@boulder.Colorado.EDU>, colonbon@boulder.Colorado.EDU (Glenn T. Colon-Bonet) writes:
>   2. build an external infrared detector which will recognize the 'power'
>      button sequence and switch the AC output on/off.
> I would prefer option 2, mostly because it sounds like the most fun to build,
> and doesn't require voiding the warranty!
> 
>    I would like to know if anyone has worked with infrared remotes and
> knows what kind of protocols are used, is it asynch with start/stop pulses
> and some kind of encoding for the keys on the remote?  Also, I am not
> sure of how to go about amplifying the signal detected, I presume, 
> from an infrared photodiode detector. 

In the February and March, 1987 issues of Byte magazine, Steve Ciarcia
had a couple of projects dealing with IR remote controls.  In the February
issue, he described how to build a tranmsitter and receiver using commercial
chips.  For example, the Motorola MC3373 is general purpose IR receiver
chip that could be used in your device.

In the March issue he describes IR controllers in general terms and
how to build a "trainable" controller which can imitate the signals
produced by almost any controller on the market.  (I built a controller
based on his ideas, it's a great toy).

-- 
Peter Fales			AT&T, Room 5B-414
				2000 N. Naperville Rd.
UUCP:	...att!ihlpb!psfales	Naperville, IL 60566
Domain: psfales@ihlpb.att.com	work:	(312) 979-8031

cdl@mplvax.EDU (Carl Lowenstein) (04/21/89)

In article <8255@boulder.Colorado.EDU> colonbon@boulder.Colorado.EDU (Glenn T. Colon-Bonet) writes:
>Howdy,
>    I recently purchased a VCR and I would like to be able to use the
>'power' button on the remote to turn on the TV as well as the VCR.
>Unfortunately, the VCR doesn't have a switched AC outlet, as I would
>have liked.  I would like to build a circuit to do this, but I'm not
>sure which approach to use.  I'm considering:
>  1. open up the VCR and find a switched output which could be used to
>     drive a relay for the switched AC circuit
>  2. build an external infrared detector which will recognize the 'power'
>     button sequence and switch the AC output on/off.

Consider the following:
   3. buy (or build) a circuit which senses the primary current flow to
the VCR.  This can then operate a relay to switch one or more auxiliary
outlets.  You should be able to get such a thing at your nearby friendly
Radio Shack or Heathkit store.

Common applications for these devices are turning on your computer's
peripherals when you turn on the CPU, turning on the rest of your
stereo system when you turn on the tuner, etc. etc.  In the olden days
they were used to turn off your stereo (hi-fi if really olden) when the
last record played on the automatic turntable. (record player if really
olden).

The paragraph above full of trivia was added to satisfy 'rn'.  Bah!!

-- 
	carl lowenstein		marine physical lab	u.c. san diego
	{decvax|ucbvax}	!ucsd!mplvax!cdl
	cdl@mplvax.ucsd.edu