Hi Bob,

I had a quick read of your referred to post and your description of the dimmer and bridge rectifier controller.
Using a high voltage electrolytic capacitor on the output of the bridge would have given you a more stable, measurable, DC level, but as you pointed out the DC motor doesn't care at all.

It is one technique that is used in DC and universal motor controllers to replace two of the rectifiers in the bridge with thyristors, so that the DC output from the bridge rectifier can be varied.