Re: [CAD_CAM_EDM_DRO] Re: Servo heat-sensors or paranoia?

This may be over simplification, but why not just find three cheap digital ammeters to monitor the servo motor leads and mount their LCD screens in the console/cabinet?

Ron

caudlet <thom@...> wrote:

>
> I like this idea. Are you using an LM3914 or similar? Connected

across a

> current-sense resistor?

You could sense across a series fuse on each motor. A simple
absolute value (precision rectifier) can be built with two gates of
an LM324 and a couple of signal diodes. An integrator stage (one
more LM324 gate) to average the current pulses and the last amp as a
scaling buffer to drive an LM3914. The above configuration needs a
floating power supply so it can do the high side sensing.

A very low value resistor in the ground return of each motor allows
sensing with ground reference.

One last idea. A small 1/2" toroid current sense transformer made for
switching power supplies will sense the PWM current with no loss.
Just run either motor wire through it and turn the secondary current
into voltage across a small load resistor. You still need the
precision rectifier and other stages but it's got zero insertion loss.





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