🚀 go-pugleaf

In article <7574@scolex.sco.COM>, deanr@sco.COM (Dean Reece) writes...
>
>Hi, I need some help with RS232 drivers/receivers
>I'm building a project that needs a standard RS232 port, but only has
>available supplies of +5, +12, and +24 volts.  I thought that I
>might be able to use the 0(GND), +12, and +24 kinda like the +/- 12v supply
>usually called for.  I couldn't think of any trivial way to do this,

How about the following...

Remember that an RS232 needs only a 6V level shift, 3V on either
side of ground (lower than -3V is a logical '1', greater than +3V
is a logical '1').

First convert the signals to CMOS levels, i.e. 0V and 5V for 0 and 1.
Then use variable voltage followers to set up a 4.5V and 9V references.
Send the 0-5V signals into a CMOS driver powered by the 9V circuit.
The output will be signals will a shift of 0-9V.

Connect the output of the CMOS driver (high current) to the RS232
data line.  Connect the signal ground of the RS232 to the 4.5 V ref.

I think this is a quick way to solve the problem, and uses only
2 cmos high-current drivers and 2 voltage references.  

Joe