[GreenKeys] Machine speed and VFDs

[Jim Haynes]

Seems to me it would be a lot easier to do with a UART than with a
variable-frequency motor inverter.  The motor (synchronous) doesn't have
enough iron and copper to run at a lower frequency than it is designed
for, so is likely to overheat.  You might have success running it with
60wpm gears and increasing the frequency to get higher speeds.  Still it
seems like a lot of doing to make a variable frequency inverter that
will deliver enough power to run the motor.

The UART is a 1980s way to solve the problem.  I guess a microcomputer
like the Raspberry Pi would be an up-to-date way.  Or you coud find an
old DOS computer with two COM ports and maybe write a program in BASIC
to do what you want.