[sdiy] Strobe Tuner

[Christian Bergmiller]

Hello,

the topic of stobe tuners pops up from time to time on this list, so i
hope to get
some answers ;-)

I successfully built my own version of a led based strobe tuner some time ago.
it uses an avr to light a line of leds in circular fashion and fixed frequency.
the frequency is genrated with a phase akku oszillator (in the avr).
The incoming signal is rectified and enables the string of leds - the
strobe pattern emerges..

Now i would like to try and build a "real" strobe tuner with a rotating disk..
What would be a good way to rotate the disk with the needed frequency precision?

In cdrom drives, so called brush less dc motors with 3 phases can be found.
the needed driver chip is often mounted near to the motor.
this chips are fed by an analog signal and spin the motor faster as
the signal level
goes up..
I could try to generate sort of a feedback loop with the avr, but will the
precision that is needed (to measure the speed and to do the control
signal for the motor) be easy to attain?

otherwise i could try to spin the motor by generating an three phase motor
drive signal of fixed frequency in the avr. the motor should run synchronous
with this drive under low loads, at least i hope so..

some suggestions?

christian