Re: [CAD_CAM_EDM_DRO] Bridge Rectification

jmw@... wrote:

> More C&H. The motor crew was testing DC motors using an AC variable
> transformer and a little half-ice-cube sized "bridge rectifier" with
> four lugs--2 in and 2 out. Cost was two or three bucks and the
> counterman claimed, "Ya can pull 40 amps thru these things."
>
> Is this a reasonable setup for motor testing, and one unlikely to
> release magic smoke? By reasonable, I mean is power of this quality
> similar enough to that of a "real" power supply as to render
> meaningful tests?

No, it is not. You are running the motor on pulsating DC. If you
read the apparent voltage with an ordinary analog or digital meter,
you will not get an accurate reading of the effective voltage, because
it is not DC or sinusoidal AC. So, you will not get the correct
value of volts / 1000 RPM.

Jon