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Re: Viewfinder Question...

On Wed, 5 Aug 1998  wrote:
> what you've come across is probably a "real" viewfinder, e.g. one that
> can properly display 80x25 text (presume you have 80 col card or the like
> in the apple computer -- http://wearcam.org/wearhow/node4.html).
It's actually a Laser 128, but yes, it has the equivalent of a 128K 80-col
card.  The focusing lens is rather poor, and causes the text around the
edges to become unreadable, but this should be fairly easy to replace.

> you should get the viewfinder displaying ntsc any way possible (such as
> in-situ, in the original system), then measure with scope the waveforms
> to see which is sync and which is video.
It takes two separate composite inputs, and seems to run off of 12vdc.
There is a switch to choose between inputs.  Hehe- I think I may try
attaching a small infrared camera ($162 last time I checked
http://www.allcorp.com - no lens, I believe) as well.

> measure the video too, to see if it needs level shift, etc., make from simple
> op amp.
The inputs are NTSC levels, not TTL.

> careful, as voltages typically up to 5000 volts in typical "real"
> viewfinders.
Indeed.  I nearly electrocuted myself once trying to fix an old monitor.
:)  The one-hand rule is the best thing since peach pie.

> when done, email me your findings 
> if you'd like them included in the wearhow (wearcam.org/wearhow/index.html)
> or the review of wearcomp displays.
Well, here is what it looks like so far.  I am not completely sure of this
info, nor is it complete, but here is what I know so far:

Male DIN-8 (on viewfinder):

    4
  3   5
 2  8  6
  1   7

6-      Video input #1
4-      +12v
shield- ground (duh :)

There seems to be no output from the camera on any other pins except 3,
which according to my (terribly in need of calibration) 'scope is a
constant 1 volt on pin 3.  I had no external video source connected at the
time, so I don't know which pin takes video #2 (yet).

Panasonic no longer supports this device, and I found no documents
containing the part number and panasonic on an altavista search. :(

I shall examine it further (and provide more info) if I am able to
purchase the device. For now, I am afraid I might break it (like I did my
first one. :( ).

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