TV video input

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wwillis0
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TV video input

Post by wwillis0 » Sat Nov 13, 2004 3:34 pm

I have a 5" b/w TV with am/fm built in. Can any one tell me how to add inputs for audio and video, so I can connect a cctv video camera to it?

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Chris Smith
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Re: TV video input

Post by Chris Smith » Sat Nov 13, 2004 4:10 pm

First, you need a modulator to turn your camera out put signal into a Chanel 3/4 output signal.<p>Then If your TV doesn’t have a cable input connector but only has two screws/two wires for the antenna lead, you will need a balun transformer that looks like a cable fitting attached to a small drum like transformer, with two leads and "Y" screw fittings attached in two leads like your antenna wires. This matches the input impedance mismatch that you would find if you tried to directly attach cable fitting to Y type fitting.

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jwax
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Re: TV video input

Post by jwax » Sat Nov 13, 2004 5:01 pm


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jwax
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Re: TV video input

Post by jwax » Sat Nov 13, 2004 5:06 pm

Home Depot link didn't work, but it is:
RCA
RF Modulator
Model CRF900
Internet/Catalog 161273
Store SKU # 140 276 <p>Good luck!

Enzo
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Re: TV video input

Post by Enzo » Sun Nov 14, 2004 4:08 pm

RF modulators for TV can also be had at Radio Shack, Best Buy, and most anywhere that sells stuff for VCRs, DVD players, etc. it is a common item.

Dean Huster
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Re: TV video input

Post by Dean Huster » Wed Nov 17, 2004 3:09 am

What you DON'T want to do is try to add jacks for direct A/V input. Those little sets are usually "hot" chassis types when powered by the mains and would be very difficult to safely isolate. As inexpensive as little TVs are getting these days, it shouldn't be difficult to find one under $50 that has external A/V inputs. My little LCD TV I bought 10 or 15 years ago does and I bought it for that very same purpose -- to use as a monitor for my video camera in crowd shots where I couldn't use the viewfinder in the days before camcorders were available with built-in LCD screens. The little TV had A/V input via a 3.5 mm 2-circuit jack.<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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Externet
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Re: TV video input

Post by Externet » Wed Nov 17, 2004 7:16 am

Hi.
In the event of insisting to add a video input to a television that does not have it; <p>¿Would the video signal correct entry point be the contrast control wiper terminal?<p>[An external audio signal entry point is obviously the volume control wiper]<p>Thanks,
Miguel
- Abolish the deciBel ! -

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jollyrgr
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Re: TV video input

Post by jollyrgr » Fri Nov 19, 2004 6:03 pm

Depending on the set's design, it might be possible to add the video and audio inputs. But there is no magic answer of where to modify the circuitry. In other words I cannot say cut the blue wire and insert audio here, cut the yellow wire and insert video there.<p>What you might be able to do is examine the circuitry and find where the tuner section is at. If the circuit board is nicely silkscreened you will be able to see the different sections and know what each does. This is wishful thinking but there are times you get lucky. <p>If you were only asking about audio, such as in a radio, this would be an easy task. But with video, especially with a CRT based TV, you are looking at potential problems; namely high voltage. Even on a small set of five inches you are looking at voltages of 12,000 volts. No, that is not a typo. Yes it is very low current but painful and potentially dangerous especially if you are not expecting it. And as Dean points out these sets can have hot chassis. This means that you could potentially have the chassis connected to the "HOT" of an AC line. It would be the same as sticking a paper clip into an AC outlet; very dangerous.<p>Now that you have been warned, let me tell you what to look for. Check for the buttons or dial or whatever the tuner section is controlled by and follow that section as the tuner. Somewhere will most likely be a true line level output of the tuner section for both video and audio. This will most likely be followed immediately by the section for the video and audio processing of the set. What you must do is break these connections and isert your own path for video and audio. If you want to be real clever you would use a switch to flip between the normal TV connection and the external connections. If the original chassis was designed to accept different features (such as external inputs) you might see a jumper wire filling this section, bypassing the empty component holes.<p>I can tell you what I suggest, the same thing most others have; an RF modulator. But if you want "compact" you might be able to go one other trick. Get an RF modulator for something like a Game Cube or other video game (these can be found for under $15). Modify it to fit inside your set and add RCA jacks to the outside of the TV connected to the RF modulator on the inside. Power the RF modulator from a tap point inside the set (assuming you can find the right voltage). Add a switch that connects/disconnects the external antenna connection and connects it to the RF modulator. Then the only complex step is to tune the TV to channel 3 or 4. But this is not much different than tuning to the AUX or VIDEO input of a regular TV.<p>[ November 19, 2004: Message edited by: Jolly Roger ]</p>
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Enzo
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Re: TV video input

Post by Enzo » Fri Nov 19, 2004 8:13 pm

The video signal would be present at the contrast control probably, but the sync was likely separated from it before that point, so you would need to get sync in there somehow too.

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Chris Smith
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Re: TV video input

Post by Chris Smith » Sat Nov 20, 2004 7:59 am

No need to Reinvent the wheel, Stick to your antenna input, problem solved with a $1.00 balun transformer.

josmith
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Re: TV video input

Post by josmith » Sat Nov 20, 2004 8:55 am

If you don't want to buy a modulator(which will cost more than the 5" tv) fine a junk vcr and use the a/v inputs and then hook the rf output to the tv.

ad5mb
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Re: TV video input

Post by ad5mb » Sun Nov 21, 2004 7:47 am

Everybody and their dog is selling a little BW set for $20. Video and one audio input. <p>Chiefs Auto, Oshmans, everywhere.<p>Here's one on eBay, Big time $13:<p>http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 5732668089& rd=1&ssPageName=WDVW<p>For ham radio folks: Tune it just below UHF 14, it gets the ham ATV frequency that corresponds to cable channel 60 - CATV60.<p>[ November 21, 2004: Message edited by: ad5mb ]</p>

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