Re: Gravitar in my Space Duel?

If you look at the edge connector on the PCB you will see that the +5V pins and the
'sense' pins are the same. The purpose of the sense pins is to provide a very low current
path from the +5V on the PCB back to the power supply. Because the path is low current,
the possiblility of a voltage drop across the pin connection and wire is extremely small,
whereas the potential for a voltage drop across the pin connection on the main +5V wire is
much greater. That way, if there is a perfect 5.00V coming out of the reg/aud II board and
there is a voltage drop of .25V on the main +5V pins, that would put 4.75V on the game
PCB, the sense wire sends this voltage back to the Aud/RegII board and it compares it to a
reference of +5V. Since it is low, the Aud/Reg II board will theoretically put out a new
adjusted voltage of 5.25V so that with the voltage drop taken
into consideration, the PCB now has a perfect 5.00V as it should.
  Sorry for the long winded explanation. Basically, you can see if you look at the PCB
pinouts, the symmetrical connection pattern of the power supply pins. You can even plug it
in backwards and the way Atari made it, you most likely will not do any damage! Nice!

tom mcclintock wrote:
>
> So after six months, I now have a working Space Duel in my house. And
> without missing a beat, I want to put one of my Gravitar boards in the
> cabinet and play that as well. I know there are control panel
> differences, and the harness is *supposed* to be the same.
>
> However, after studying the pinouts, it seems Gravitar asks for the
> +Sense and a +5V in a different location that the Space Duel harness
> provides. (specifically, the SD harness provides +Sense on pin 21, while
> the Gravitar board looks for Ground on Pin 21, + Sense on Pin Z and +5V
> on pin Y)
>
> Assuming I plug my Gravitar board into the SD harness, what will happen
> to the Gravitar board without the proper Sense and +5V ?
>
> Thanks in advance.
> tom
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Received on Fri Mar 10 16:36:58 2000