Chris wrote:

Hi all,

I am looking for a schematic for a copy counter for a Minolta 7255 copier.
I can't think that it would be too hard to make, a couple of flip-flops,
interface circuitry and display driver.
Problem is that I don't know the pin-out of the interface, or the signals
that are sent through it and the fact that my knowledge of digital circuitry
is at the level of digital electronics 101/102. Although I have done some
electronic repair at the level of repairing Commodore 64 and Apple II+
computers at the component level so I do understand a little - basic level
only.
Even the signaling of the copier interface would be a great help.

Best way to approach this is to ignore the existing copier circuitry.
Hacking into that could be a major chore. You'd be better off affixing a
dedicated microswitch to some part of the copier mechanism hat cycles
one per copy and count that.

The simplest way to handle this would be with a microcontroller. Your
application is simple enough to accomplish with something like a Basic
Stamp. See http://www.parallax.com/
There are add-on modules available, such as LCD displays, or you could
do your own with a couple of 7 segment LED displays.

Consider whether your application will require non-volatile memory of
the current count (store it when the power is off).

The simplest counter would be an electromechanical counter, driven by
the dedicated microswitch. But not nearly as much fun, if that's part of
the project requirements.

--
Paul Hovnanian
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668: The Neighbor of the Beast