Newsgroups: sci.electronics
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Batty monitors and cheap video
Message-ID: <1989Sep30.055912.14883@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1989Sep28.122217.26867@watcsc.waterloo.edu> <57732@psuecl.bitnet>
Date: Sat, 30 Sep 89 05:59:12 GMT

In article <57732@psuecl.bitnet> peg@psuecl.bitnet writes:
>> To use the thing as a camera, just charge up the thing to all 1's, wait for a
>> bit, and then check which bits are discharged by the ambient light.
>
>Well, this actually works, in a manner of speaking.  The devices are called
>CCD's, charged coupled devices, and are used for picture tubes in most
>camcorders and video cameras.  As for making one from an actual RAM, I
>seriously, seriously, seriously doubt that you can get ANYTHING useful by
>opening up a RAM chip, but you are welcome to try.

Sorry, you lose:  it's been done and it works.  Several hobbyist sources,
notably Martin Weinstein's book "Android Design", have details.  How well
it would work with today's RAMs is not clear.  Certainly one would get a
segmented image, since they don't have all the memory bits in one array.
Probably a bigger problem is finding a DRAM in a package you can pop the
lid off of; taking the plastic off a plastic-packaged one without ruining
the chip is almost certainly impossible.

Micron Technology at one point even sold DRAMs with transparent lids as
bargain-basement imagers.
-- 
"Where is D.D. Harriman now,   |     Henry Spencer at U of Toronto Zoology
when we really *need* him?"    | uunet!attcan!utzoo!henry henry@zoo.toronto.edu