I need a design for a simple power supply to provide power to a DC motor
for use in a constant tension device. Need the design to vary the
voltage to the motor from a external pot that has an arm that rides on
the spool I am unwinding. The power supply would need to provide about
2 amps max to run the motor at something like about 0 - 12 volts. The
motor would provide tension on the spool that would vary as the size
changed. If someone has another suggestion I would be open to that
also. I looked at a device I found on the web from a company called
Magnetic Tech. that uses a magnetic brake that probably would work
however it is priced at almost $600/ unit. I have been using a
mechanical brake that places drag on the spool however this is not
constant tension and I have increased the speed of the unwinding and
this has caused me alot of problems.

Thanks -

Barry