[time-nuts] Antique precision timing device without

[Brooke Clarke]

Hi Morris:

The GR 631 StroboTac includes a power line driven vibrating reed sticking into the reflector and so it's motion is 
stopped by the strobe.
The patent has hand written comments regarding that idea.
http://www.prc68.com/I/GRstrobotac.html#2331317
http://www.prc68.com/I/Images/Strobotac631-01b.jpg

The idea here was to use the power line as a frequency reference.
This would be fine since most of the applications for this strobe were related to line driven motors.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

-------- Original Message --------
> HI all,
>
> Thanks to all those who responded to my post and also for the great pics of
> other tuning forks. It's amazing that they were still being used for
> electronic purposes as recently as the 1960s. Actually now that I think
> about it I have seen little tuning forks used to check the function of
> modern police speed radars so they still have some use. Musicians don't use
> them any more - guitar players will know the little electronic tuning
> devices clipped to the  neck of the instrument that displays the frequency
> or key of each string. Doctors still use 125 Hz forks to test vibration
> sense and higher frequency ones to test for conductive hearing loss.
>
> In answer to some of the questions posted: no there was no documentation
> with the unit. The most useful thing was the "12 volts in" label on the
> power socket so I knew where to start. The rest of it was necktop analysis.
> The fork is maintained by means of a central electromagnet and small leaf
> spring contacts on the tines - they also provide the 25 Hz power for the
> motor which runs at 12 volts. Of course they would reduce the Q of the fork
> a little and affect its resonance but I'm sure that was taken into  account
> by the designer and the frequency & symmetry can be adjusted with the
> weights on the ends. Operating current is about 0.5A at 12 volts when
> running and 1A when the fork is not vibrating. There's a switch marked "Neon
> Lamp" that controls the AC supply to a pair of clips between the tines of
> the fork. They are about 3-4 inches apart and I have no idea what sort of
> long thin tubular lamp would fit between them. Just for fun I'm going to
> make a simple stroboscope with a 555 timer and some high intensity white
> LEDs I have lying around to see if I can use it on the fork.
>
> Cheers,
>
> Morris
>
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