Re: Exorcisor Schematic Error

At 12:40 PM 12/22/97 -0600, Joe W. wrote:
>
> While I'm at it....There is an error in the Exorcisor
>schematic....Dave probably didn't catch it yet, because he built
>his out of the exact parts....
>
> On the LS163A counters, the ENT and ENP connections are
>reversed. Pin 7 should be ENP and Pin 10 should be ENT.
>
> All the hook-up is correct on the schematic, so if you
>hook those wires up to those pins, on those actual chips,
>everything will work correctly, but with the functionality labeled
>as it is, my functional models (which don't care about pinouts)
>didn't work.
>
 The ENT / ENP error was a carry over. Whoever generated that library
at work screwed up, I never noticed it. Like Joe said it makes no
difference when wiring up to pins of real parts. Another thing
you will definitely want to look into is the CLOCK input. The
original design is marginal at best and has been giving me no end
of trouble. My Exorcisor works fine on some boards and not at all
on another. Removing the capacitors on the CLK input is a must and
getting rid of the 100 Ohm current limit resistor also should be
done. A 2K pull-up resistor at the input helped get the levels
to where they should be but I'm still going to have to improve
the ground connections. I'm getting too much ringing on the CLK
input which is probably what's causing the marginal condition.
I just wish that I had more time to play with it to get it right.
 
Received on Mon Dec 22 14:46:28 1997