6 Nov
2024
6 Nov
'24
4:39 p.m.
On Wed, Nov 6, 2024 at 4:31 PM Mike Stein via cctalk
<cctalk(a)classiccmp.org> wrote:
I use a strobe disk glued to a fridge magnet that I stick on the spindle
motor of 5 1/4" drives to confirm the speed; the trouble is that it's
becoming difficult these days to find lamps that emit light at 60 Hz. ;-)
I made a simple circuit (3 common TTL counter chips, a couple of
transistors, a 4.91...MHz crystal oscillator module, 7805 regulator
and a few passive components) that flashes 4 white LEDs either 100 or
120 times a second wth a 1/16th duty cycle. It runs off a 12V DC
supply
This will simulate a mains lamp for such a strobe disk, and of course
can be used on either '50Hz' or '60Hz' markings no matter what your
mains frequency is.
The crystall osciltor module is easily accurate enough for setting up
such motor speed controllers. I'd be happy to share the schematic but
of course I can't post it here.
If you want to avoid electronics, then stroboscopic tuning fork?
-tony