[rescue] Anyone build this kit?

[Mike Spooner]

"Valid signals are either in the range of +3 to +15 volts or the range b3 to
b15 volts with respect to the "Common Ground" (GND) pin; consequently, the
range between b3 to +3 volts is not a valid RS-232 level." All relative to
the GND pin (aka SG).

Many "5V TTL" versions only swing from 0V to +5V relative to SG, others -2.5V
to +2.5V. Neither conforms, as they use (some or more) signal levels in the
forbidden zone.


- Mike S.