Hi,

I4m going to control an small-Power AC/DC Motor.

Motor type is german-called "Reihenschlusz-Motor" which
means that rotor and field-coils are normaly connected.

  ------[]-----( O )-----

       ^Field Coil  ^Rotor with brushes

I like to controle the speed. I have the possibillity to
access the connection between field-coil and rotor.

My idea is to generate PWM using an PIC, and measuring the
bkemf with the built in A/D. Using the bkemf to determine
the speed/load.

The Motor Power-consumption  is less then .5 Amps continous. Supply
-Voltage is rectivied AC aprox. 12 - 25 Volts, 30kHz (!).

The Application is to regulate the speed of Model-Railroad-Locos.

Does somebody have Ideas, Source, descriptions, suggestions, hints ?

Kind regards,

        Stefan Sczekalla-Waldschmidt.