10 Feb
2009
10 Feb
'09
2:44 p.m.
On Tue, 2009-02-10 at 20:41 +0000, Tony Duell wrote:
If you were being excessively clever, you'd measure the speed of the
disc with the tachogenerator and apply some modulation to the twiddlepot
to let you choose any speed, right or wrong, and stick to it! If you
used a little microcontroller you could program in various test patterns
of wobbly speed, too.
Gordon
Of course, I
may well need a drive that's having speed regulation issues in
order to prove that it can track the speed correctly...
That shoukld be easy enough.. Many of the full-height 5.25" drives used a
combined motor and tachogenerator with a belt drive to the spindle. Teh
control circuit was often based round an LM2917 chip with a twiddlepot to
set the speed.
Eitehr turn the pot by hand to get the thing off-speed., or find some way
to inject a very slow analogue signal into the circuit to cause the speed
to vary a bit over time.