Re: [CAD_CAM_EDM_DRO] Another Solution!!!!To convert Quadrature Encoder signals to Tachogenerator signals

Babar wrote:

>Hi All,
>
>I was in the process of developing the circuit
>suggested by Jon to convert Quadrature Encoder signals
>to Tachogenerator signals, when this new idea striked
>me,
>The idea is that , Can I use a small Dc motor ( used
>in CDROM drives or tape recorders) in place of
>Tachogenerator. Due to the samll size of these motors
>it is easy to make the mechanical attachment for
>connecting with motor. Regarding the output voltage, I
>think an OP-Amp can be used for scaling.
>
>

The ordinary motors from tape recorders, etc. are not very
good, and will produce a great deal of voltage ripple when turned
at a constant rate. Motors from CDROM drives, etc. are not DC
brush motors, excepting the load-unload motor, in most cases.
Maybe some used DC brush motors for the tracking drive.

What you want, if you can find them surplus, are Maxon motors.
They make DC brush tachs, and they also make a line of small
instrument motors that are essentially identical to their very
fine DC tachs. These motors are usually black with red plastic
end caps. They have a silver-plated commutator with silver
brushes. These motors use an ironless rotor, and have so
little voltage ripple youd think it was a battery if you looked
at the output on an oscilloscope. If you are going to connect
these to a velocity servo amplifier, the op amp for tach scaling
is already there.

Jon