[Coco] RE: [Color Computer] Opinion time
gene.heskett at verizon.net
Sun Apr 9 23:48:08 EDT 2006
On Sunday 09 April 2006 17:08, RJRTTY at aol.com wrote:
>In a message dated 4/9/06 1:44:27 P.M. Eastern Daylight Time,
>gene.heskett at verizon.net writes:
>>I wondered about that myself. But then one needs to trim the gain
>> to put the normal britness levels for half and full in the middle
>> of the deadband so caused. We're doing that now anyway, but...
>>What sort of rise & fall times are you getting at the gime outputs?
>Ok I haven't scoped the signals other than to collect thier peak
>values but I will go back and measure the rise times when i
>get back to my setup. What I will do is test several machines
>and see what is typical. I do know from experience that
>a 50 ohm input is better than 75 which makes me wonder
>how much resistance is in the ribbon cable and it's connectors.
I had at one time a few months ago, actually did some checking right at
the gime pins, but it was no faster there than it was after being run
thru the triplet of emitter followers in the coco3 that isolate the
cable from the gime. The emitter followers are 2sc945's, basicly 100
to the dollar stuff, but also several hundred megs of bandwidth, so I
don't think thats slowing it down any. My 10x scope probes are about 7
to 8 pf at the bare tip, so I've no idea if thats a significant load or
>Yes I am "tuning" the gain pot for the dead band on
>units i send out but I think dropping a bit will make the
>dead band larger and easier to hit leaving some room for
>drift as the components age. I want to avoid the need
>for the user to open the enclosure to adjust something.
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.
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