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Subject: 
Re: Rolling ball clock revisited
Newsgroups: 
lugnet.technic, lugnet.robotics
Date: 
Tue, 7 Dec 2004 16:37:07 GMT
Viewed: 
3188 times
  
In lugnet.announce.moc, Philippe Hurbain wrote:
   I finally rebuilt Bob Kojima’s rolling ball clock with RCX control (and other minor modifications)



Description of these modifications, program, photos, videos are here

Special thanks to Bob for the time spent to LDraw his wonderful model!

Philo

I love it! Very nicely done!

It was interesting to read this bit off your website--

“ The problem should have been very simple: each minute, start the elevator until a ball is detected by one sensor. Unfortunately, my first try over a several hours period showed me that my clock was fast, several seconds each hour! After eliminating all mechanical possibilities (two balls at a time, or an undetected ball), I concluded that my RCX itself was fast... To make sure, I finally put a frequency meter probe on RCX crystal, and indeed it oscillates at 16.03 MHz instead of 16.00 MHz. So I finally added some code to wait for 6.92 seconds each hour. ”

This explains much to me--I have an 1.0 AC’d RCX that’s been on for months but almost weekly I have to reset the clock. Thanks for the info on the fast clock!

Take care,

Dave K



Message has 1 Reply:
  RCX has a fast clock, was Re: Rolling ball clock revisited
 
Hello dave, (...) A made an experiment this night using a RCX 2.0, the clock was fast by about 10s per hour. I suppose that this problem comes from bad capacitor loading of the crystal used on RCX. Crystals need to see some capacitance to oscillate (...) (20 years ago, 8-Dec-04, to lugnet.technic, lugnet.robotics)

Message is in Reply To:
  Rolling ball clock revisited
 
I finally rebuilt (URL) Bob Kojima's rolling ball clock> with RCX control (and other minor modifications) (URL) Description of these modifications, program, photos, videos are (URL) here> Special thanks to Bob for the time spent to LDraw his (...) (20 years ago, 7-Dec-04, to lugnet.announce.moc, lugnet.technic, lugnet.robotics, FTX)  

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