22 Sep
2013
22 Sep
'13
5:04 p.m.
On 2013 Sep 22, at 4:10 PM, dwight elvey wrote:
I was thinking along that line too if the converter has to be made to
work at a higher voltage, but figure Josh should first confirm
whether it's working properly at any voltage; it might function at
20V/40mA if it's OK.
From: hilpert
at cs.ubc.ca
On 2013 Sep 22, at 8:10 AM, dwight elvey wrote:
I'm thinking the only practical way to deal with it, other
that removing the -30v is to break the wire to the
Vcc of the opto, put a resistor and a zener to limit the
voltage.
It shouldn't need more than a 10 or 20 uA to the opto. Thanks Brent
I'd not noticed the diode path to -15v.
I know, it's horrible trying to figure things out when they're drawn
in a convoluted manner as it is. That's why I redrew it, and do so
with lots of things, so (as much as reasonably possible) the E
potential is consistently increasing in the vertical direction.
I recall trying to figure out the drawing for the
teletype's
paper tape reader power supply. I think the draft
person that makes the drawing had no technical
background. They just needed to make it electrically correct.
Dwight
I've long had the impression that most manufacturers' process to
produce a schematic is the design engineer hands off some scraps of
the original to a draftperson whose priority is "how do I squeeze
these lines and symbols onto a page of paper". I don't have it around
any longer, but IIRC the fold-out APPLE II schematic was horrible,
with gates oriented in all directions and signal lines traversing
back and forth everywhere. No worse than a lot of stuff though.