"Angus Bryant" wrote in message ...
frequency) has this effect. The advantage of using pulse-width modulation
(PWM) switching to achieve this is that the switching process is very (90%)
efficient, since the devices only pass high currents at high voltages (hence
burn lots of power) when switching. You could use a linear amplifier (i.e.

How does that efficiency compare with the old DC systems where at full power
the motor was pretty much just connected directly to the power rail(s) as
opposed to the new systems where you still have the electronics driving the
motors?

B2003