Instructables

HMD, Can I use this?

Hi all, I have a view finder from a camcorder of an unknown make. It has four wires 1 white and 3 grey. I was wondering if anyone had a way to test and find out which wire was which.  I dont have a oscilloscope
but any other ways are welcome. Thanks in advance for your time and effort.

orksecurity4 years ago
I would guess that two of the wires are power and two are signal -- or perhaps one is power, one is signal, one is common ground, and the other may be either negative power or another component of signal or something of that sort.

Finding that out (and finding out what kind of power it needs, and whether you would have to preprocess the signal) is probably best approached by contacting the manufacturer of the component and asking them. If you can't figure out who they are, contact the manufacturer of the camera and ask them whether repair information is available for that model; that might contain circuit diagrams, at least at the module level, which would give you the pinouts.

If they can't help you, there are sites on the web which have copies of the maintenance manuals for some pieces of equipment, either viewable on line or for sale; that might be worth trying.

If you want to figure it out  yourself ... it would be a lot easier to look at what the camera is putting out on each pin; otherwise you need to trace through the circuitry and figure out what's connected to what, and workd backward from that to what they're doing with that wire. If youre are lucky, there may be printed or etched markings on the circuit board which say things like "Vcc" or "V+" (either of which would be a power input), which would help answer this question.

But unless you find the markings or a manual, I don't know any way that someone who doesn't have fairly deep electronic knowledge is going to reliably figure this out. If I had it in my hands I might be able to offer a bit more advice, but the photos don't have enough resolution and I'd be nervous about trying to do it remotely in any case.

Interesting project. Certainly worth trying... though that looks like it would be easier to turn into a monocular-like viewer than a HUD; it seems a bit bulky for head-mounting unless you're doing to things with mirrors/prisms to mount it alongside the head. If you make it work, let us know how it works out.
Modarius (author) 4 years ago
Ok, I found that the white wire is +5v, at least it lights up with that. It also lights up immediately, there is no "warm up" time needed. The next step would be to find an S video source. I ultimately plan on hooking this up to a small camera that I have and doing something like night vision :D.
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Re-design4 years ago
Did you have any luck? <br /><br />I found another <a href="http://www.instructables.com/id/Googfan_s-Mini-TV/">link</a>.<br />
Re-design4 years ago
<a href="http://www.youtube.com/watch?v=xS0HwHlEzRM&feature=related">Check out this link.</a><br />
lemonie4 years ago
That's compact! Can you see what the signal-decoder looks like in there? Considering that two of the wires are power & "ground" you've only got one or two for signal and we're not sure what type of signal that is.

L
DIY projector! Definitely worth it.
Imagine watching your favorite Youtube videos ON YOUR ENTIRE BEDROOM WALL!
Win.
I've been hunting for a service manual to see if I can tell you which wire is which. No luck so far, but I'd probably have better luck if I knew the model of this gadget.<br /><br />Here's what I do know and what I at least suspect:<br /><br />I would guess this thing can display an ordinary video input (ie. something you can pull from an RCA or s-video jack). Most likely, it's only interested in a signal called luminance. It's worth a shot, but figure out power and ground first. <br /><br />If it accepts s-video, which is most likely, you only need two of the pins from that source. Pins 1 and 3, which are luminance (Y) and it's ground. That means you need of the two wires from the camcorder viewfinder. <br /><br />Correct voltage is probably close to 5v (educated guess, simply due to the fact that it's such a common voltage for pre-fab components), amperage I can't even guess.<br /><br />I gathered some ideas from others who've messed with this and wrote a little step-by-step. <br /><br />-GET AND PUT ON A PAIR OF RUBBER WORK GLOVES THAT ARE DESIGNED FOR PROTECTION AGAINST ELECTRIC SHOCK.<br /><br />-First off, a 9v battery can help you find the positive and negative wires. Try a combination of any two with the 9v, then switch them around. If the cathode lights up, you've got it! If it doesn't light up, try another combination and repeat. I'd start with the white wire as negative and the furthest one as positive (and switch if that fails). <br /><br />-Once you successfully find the power, try 3v's (2x any 1.5v battery), 4.5v (3x), and then 6v (4x) until it lights up. That should get you a value that's reasonably close to what it actually wants. Go with the lowest one that works. IF you think it might be close to 5v, you could try power from a USB port. No promises you won't fry your computer, so test first with a cheap USB wall-wart. You can also get 5v adapters from a lot of cordless and cellular phones.<br /><br />-Before each video test, it's best to make sure the gadget that's feeding it is turned on, showing an image or video, and set to the right output. If possible, test to make sure it's outputting correctly by connecting it with another compatible device.<br /><br />-After you get powered, test with a feed from s-video first. It's most likely to work. Your two remaining viewfinder wires are going to connect to pin 1 and 3 on your s-video source ( http://en.wikipedia.org/wiki/S-Video ), so try it and if it doesn't work, switch them around. If it doesn't work the second time, move on to an RCA video source.<br /><br />-Yellow RCA jacks usually mean composite video, and include color information. I'd try it anyway, but you might only get snow or you might get a really washed-out picture in areas that would have had strong colors. Anyway, to test plug an RCA cable in and then touch the signal wires from your viewfinder to the inside pin and the outside ring of the jack on the other end. Switch if failed.<br /><br />-If you're lucky enough to have a YPbPr video output on your VCR ( http://en.wikipedia.org/wiki/YPbPr ) try just the Y (luminance, green cable) from that. These are RCA connectors too, so you can use the same cable you used in the previous experiment.<br /><br />Best of luck!<br /><br /><br />
Forgot to mention, doing the power tests... Supply power for 30-60 seconds before assuming it doesn't work.  Some of these take up to a minute to light up, and may take longer while you're messing with things.
Modarius (author) 4 years ago
Whoops! Sorry I didn't mean to click the "this is the best answer button". These are all great answers and I will try some of the things sugested. Any more info would also be apreciated but this looks like all there is to know.
Re-design4 years ago
That looks like one of the old view finders that used a cathode ray tube.  Be very careful if you try to power that up.  It would use several thousand volts.  It might tingle a little if you touch the wrong thing.

Are these 4 wires the only wires that connected it to the camera?

If so then I would assume that 2 wires were for power and 2 wires were for the signal.  I have not idea which is which but you might be able to figure out by looking at the circuit board.  And folowing them to see where they lead.