Sean wrote:
>This is changing the topic slightly, but I have always wondered: how do DC
>powered tape players/recorders maintain the proper tape feed speed? Do they
>have some means of measuring the speed and perform feedback or do they
>simply rely on the load and motor specs being relatively constant? Since
>even a few percent change is quite noticeable, this would seem to be
>inadequate for cheap motors.

The really cheap ones had mechanical governors. Sort of like a centrifugal
switch that opens when the motor spins too fast. (on/off regulation)
New ones have the drive circuit built in to detect the spikes in motor current
as the brushes contact different portions of the armature. Higher quality
ones are direct drive (induction) with a hall effect or similar feedback.
Regards...

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