On 5/10/2006 at 3:25 PM Bill Sudbrink wrote:
It gets even simpler if you omit the circuitry that
taps
voltage from the RS-232 interface and just supply a couple
of 9-volt batteries (or some other +/- 7 to 12 volt power
supply).
Yeah, I was thinking that a MAX 232 would handle the RS-232 level
translation to and from TTL, so then it'd just boil down to mostly a +5
logic supply, the loop supply and some opto's. If you didn't care about
loop isolation, you could even drop the loop supply through a 7805 for the
very little +5 that you'd need.