[Coco] Telepak RS232 Pak

[Gene Heskett]

On Thursday 12 February 2009, Roger Taylor wrote:
>At 11:49 AM 1/17/2009, you wrote:
>>So does mine, I made one of them out of a modem pack too, but it
>>only works in
>>an MPI because those level translator chips need its plus and minus 12
>> volts, which the coco 3 does not supply, and which the older coco's only
>> supplied very marginally, around +-9 volts IIRC.  That is enough to make
>> it work 99.9% of the time, but leaves precious little over drive for noise
>> margins and poor or long cabling.
>>
>>For all new designs, investigate the MAX-232 line of chips for that
>> function, which contain their own charge pump level translators that are
>> probably 500% more efficient than the Aztec mini-switcher in the RS-232
>> Deluxe pack ever thought of being.  That puppy ran HOT!  Or did in the 2 I
>> have.  Neither have survived the ravages of age and 24/7 uptimes at the
>> Heskett ranchette.
>
>Gene, I was reading back on our discussion about the 6551 paks
>running or not running on a CoCo 3.
>
>Reading up on the MAX232 I see it generates (from a single 5v supply)
>+-7.5v, not +-12v signals.
>http://en.wikipedia.org/wiki/MAX232

Given that the rx logic threshold specs are at about +- 3 volts, +- 7.5 s/b 
more than enough.


-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
You'd best be snoozin', 'cause you don't be gettin' no work done at 5 a.m.
anyway.
		-- From the wall of the Wurster Hall stairwell