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From: murthy@arnor.watson.ibm.com (Sesh Murthy)
Newsgroups: rec.ham-radio,sci.electronics
Subject: Making a clodk go at twice the normal speed.
Message-ID: <1990Aug23.173721.7942@arnor.uucp>
Date: 23 Aug 90 17:37:21 GMT
References: <1990Jun7.141107.6790@bnrgate.bnr.ca>
Sender: news@arnor.uucp (NNTP News Poster)
Organization: IBM T.J. Watson Research Center
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A friend of mine would like to change the speed up a clock by a factor
of 2.0 or 0.5 for a psychology experiment.  

I was wondering if there is any simple way to do this.

I know that the commercially avialable battery driven clocks use a
crystal, bring down the frequency using a divider and then drive a
stepper motor.  This then drives some gears that drive the minute and
second hands.  I figured that changing the voltage would not help in
this case.   

Is it possible to change the gearing or the crystal frequency in a
simple manner.  I am willing to buy a clock in kit form, if these are
available,  and then put a divider in the circuit which can be
switched on and off by a switch.  I think gears are an inelegant
solution.  

The other things I though of was to get a wall clock that operates on
50 Hz, 110 v and somehow double the frequency of the current.  Would
this work?

Is there a simple way to double the frequency of the Ac going into the
clock.  The two ways I could think of doing this were 
1. Have a motor pair, and vary the speed of the motor and hence the
frequency of the current generated by the AC generator.
2. Use an SCR to chop up the incoming sinewave so as to double the
frequency.  Will this work?

If someone can tell me of a simpler way of doing things, or a simple
way to implement any of these ideas, I would be grateful.

Thanks

Sesh Murthy