[Coco] RE: [Color Computer] Opinion time

[Gene Heskett]

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?
>>
>>>Roy
>
>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 
not.

>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.
>
>
>Roy

-- 
Cheers, Gene
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