22 Nov
2007
22 Nov
'07
9:12 p.m.
On 22 Nov 2007 at 12:17, Fred Cisin wrote:
Is there some reason to not check the spindle speed in
software (watch for
index pulses)?
I gather that the system that these are hooked to is an S100 box that
may not have any sort of timer facility in it. To be sure, it would
be possible to hook at least the index link to a PC parallel port for
checking--but that would require writing code for the wretched thing.
Many/most drives have 50Hz/60Hz zebra discs on the
flywheel, for using a
flickering fluorescent light.
Indeed--and for 360 RPM, one can use a 45 RPM phono strobe disc just
fine (360/45 = 8.00). A 33 1/3 phono strobe disc works for 300 RPM
drives (300/33.333... = 9.00..). Strobe discs are available free for
the download at sites such as
http://www.extremephono.com/free_turntable_strobe_disk.htm
I prefer a neon bulb or LED for strobe checks--the strobe bars stand
out more clearly. Just be sure to find a disc that matches your
mains frequency (50 or 60 Hz).
Cheers,
Chuck