> Is having -10V and +10V supply hard in your design? Yeah, and not useful either - everything is 5vdc or 24vac outside the box.
> Then your next stage can use a 10V supply to hard turn on some heater and > solenoid handling FETs. The second stage just drives the thermostats - RS-232, 1wire, etc. The problem is that the wiring used is existing 18g, non-twisted, long runs. EMI is a problem, I've already replaced one of the drive transistors on the existing board, and I'd rather burn out a drive fet than an MCU. Plus the MCU doesn't have enough drive anyway (only a few mA). I did have the idea that a cheap dual op-amp could be used to provide definite transition voltages and independent drive, though, plus level translation. You can get a dual op-amp for $0.50. > For motor and power control signal runs, I am liking the idea of > plastic optical fiber, master-slave, daisy-chained-repeater > function, fail-safe-cut-cable, one-control-channel-per-wavelength, > not tristate. Overkill for a thermostat ;-) _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user