tlz@druxu.UUCP (ZrustTL) (10/08/85)
1. Is there anything that would prevent the addition of a "black
box" MTS stereo decoder to the audio circuits of a standard TV
(or is the encoding filtered out in the IF stages)?
2. If (1) is possible, does anyone know how to do this? Information
on IC part numbers, schematics, etc. appreciated.
I think this sort of thing would be a rather entertaining project.
The benefits of stereo TV alone certainly don't justify the effort
and buying a new TV soley for it's stereo capability is really insane!
Nor do I want to but the Radio Shack stereo TV tuner since it defeats
the convenience of remote control.
I am totally unfamiliar with the encoding scheme used and thought this
would be a good place to start. Thanks.
druxu!tlz _
Terry L. Zrust (_) /~\
A.T.&T. Information Systems /~\ / \/\
11900 North Pecos Street / \ /\ / | \ \
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Cornet 374-4547 _________________ _______ | ______rfg@hound.UUCP (R.GRANTGES) (10/10/85)
[] uneducated opinion: If your set brings out a jack labeled "mx" or multiplex or anything remotely like it , then you could theoretically build a decoder, or buy one. A decoder will automatically switch from stereo to mono depending on the signal, so it should not interfere with your remote control (except you would probably lose control of volume, if you now have it. If your set doesn"t have such an output you could conceivably add one, but if you have to ask, I don't think you ought to try that step as it would be tricky and set dependent. Personally, I wouldn't want to get involved. I once built a Heath color TV, and I have built simple stuff from scratch, but here I bought a converter. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg
karn@petrus.UUCP (Phil R. Karn) (10/10/85)
Here is a warning that's been made many times before, but needs to be repeated whenever the subject of TV modification comes up: ******* WARNING: Virtually all modern TV sets have their chassis connected directly to one side of the AC power line!! ******* Do not attach anything outside of the cabinet to the internal circuitry of a TV set unless 1. You run the TV through an AC power isolation transformer, or 2. Your circuit has no DC or AC path between outside circuitry and the ground reference of the TV (i.e., you use optoisolators or transformers capable of withstanding 115VAC plus spikes), or 3. You are absolutely sure that your TV is one of the very rare ones with an AC isolation transformer already built in. You should not rely on the AC power plug always being in "right" (i.e., with chassis to neutral), even if it is polarized, for the following reasons: 1. Outlets are often wired backwards. The little slot is supposed to be hot and the big one neutral, but some electricians are sloppy. 2. The outlet might still accept the plug either way, or someone might use an AC extension cord that plugs in either way. 3. Even though a neutral is grounded at the service entrance, it might be as much as several volts above ground at an outlet due to IR drops from other loads on the circuit. This can result in some pretty spectacular ground loops (i.e., melted wires and PC traces, copious smoke). In any case, be careful! Phil
bill@videovax.UUCP (William K. McFadden) (10/10/85)
In article <1664@druxu.UUCP> tlz@druxu.UUCP (ZrustTL) writes: >1. Is there anything that would prevent the addition of a "black > box" MTS stereo decoder to the audio circuits of a standard TV > (or is the encoding filtered out in the IF stages)? Most TVs filter out the MTS subcarriers at the FM detector, but you can still pick it up at the IF stages. There is one company (the name escapes me at the moment) that has developed an MTS receiver that has a sensitive RF probe that you can attach to the outside of the TV set or near the IF strip on the inside. It relies on leakage from the IF section to pick up the signal. this would let you rely on the TV's tuner only for channel selection. >2. If (1) is possible, does anyone know how to do this? Information > on IC part numbers, schematics, etc. appreciated. Building your own decoder would be difficult because of the tolerances involved and the lack of support ICs. Probably within a year or two we will see one- or two-chip MTS decoders. I would wait until they become available before attempting to build my own decoder. (Besides, most TVs would have to be modified to achieve the wide audio bandwidth required by MTS.) >I think this sort of thing would be a rather entertaining project. >The benefits of stereo TV alone certainly don't justify the effort >and buying a new TV soley for it's stereo capability is really insane! >Nor do I want to but the Radio Shack stereo TV tuner since it defeats >the convenience of remote control. >I am totally unfamiliar with the encoding scheme used and thought this >would be a good place to start. Thanks. See the article I posted to net.ham-radio a few days ago. It explains how stereo TV works. Or, if you want me to mail you a copy, let me know. -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-594 Beaverton, OR 97077 UUCP: ...{ucbvax,ihnp4,uw-beaver,decvax}!tektronix!videovax!bill GTE: (503) 627-6920 "How can I prove I am not crazy to people who are?"
knf@druxo.UUCP (FricklasK) (10/13/85)
Along these lines, i am looking for a combination surround-sound/stereo decoder
I can hook up in front of my VCR (I have a Panasonic PC1545, with HiFi but no
MTS stereo or surround decoding). I assume I will need a tuner built into the
unit. Amps for the back speakers would be nice, but not necessary. Any Ideas?
Should I move this to net.video?
'`'`'
Ken
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