[Coco] Telepak RS232 Pak

[Roger Taylor]

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

-- 
Roger Taylor

http://www.wordofthedayonline.com