Re: [CAD_CAM_EDM_DRO] this'll move the toolmaster knee

jmw@... wrote:

> GE DC servo. Specs: 70 Volts, 1725 RPM, 25.5 Amps, Field Volts 60 DC,
> 1.51 Amps, Frame 79AB. $32.50 new / surplus.
>
> Of course it's not PMDC, so it needs DC to energize its field. How
> clean should the DC be for the motor to be happy? Is a just a
> rectifier lump enough?

Most likely. The inductance of the field is HUGE, so it will be very hard
to change the field current appreciably in the time between power line
half cycles. I use DC through a large (100 W) variable resistor, so I can
set the field current (or voltage) to the specified value. I, of course,
already have a big DC supply for the servo amps. You'll need a big
DC supply for the armature, anyway, even if this is just a power feed,
so you can tap off that supply.

Jon