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Re: [TowerTalk] TIC Potentiometer

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] TIC Potentiometer
From: "David Robbins" <k1ttt@arrl.net>
Date: Fri, 04 Apr 2014 10:52:46 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Yes, the early 1032 ring I had used a pulse counter but it was just a
microswitch that counted gear teeth.  It also had limit switches that used
plastic ramp things on the inside of the ring to stop it.

David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net


-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Zivney, Terry
Sent: Friday, April 04, 2014 02:18
To: towertalk@contesting.com
Subject: Re: [TowerTalk] TIC Potentiometer

I seem to recall K1TTT said the earliest rings used a pulse counter instead
of the pot.  The implication being that the pulse counter approach had
problems and was upgraded to the pot.

A basic problem with putting the whirling magnet on the motor shaft is that
it only counts how many times the motor shaft turns.   But, many of he rings
appear to skip or slip or miss a beat (whatever you want to call it). So,
the ring location is computed by counting the number  of rotations of the
motor, not the rotations of the ring.

In my case, the pot reliably follows the motor and the spur gear that is
supposed to drive the ring.  The problem with inaccurate readout is not
caused in these cases by the pot but rather by the spur gear and ring gear
losing contact from time to time.

It seems that is also the case with the ring in the recently posted YouTube
video of a  TIC ring problem.

A pulse counting technique that is counts motor revolutions is not
inherently superior to a precision potentiometer geared to that same motor.
The selected pot is a ten-turn pot which has lots of resolution potential
(sic).   

Terry N4TZ



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