Alt-BEAM Archive
Message #02309
To: beam@corp.sgi.com
From: "Ben Hitchcock" beh01@uow.edu.au
Date: Wed, 14 Apr 1999 16:37:48 +0000
Subject: [alt-beam] Re: Timing Device
The most obvious thought was "Why not use a counter chip", but then I
thought back to my bodgy high-shool days, and remembered a crude bike
odometer I built once.
Ingredients:
1 Calculator that you can pull apart.
Some wire
A switch of some sort.
What you do is wire the switch in parallel with the 'equals' button on your
calculator. Make the switch activate every time the pendulum swings past.
You could put the switch up near the top of the string, so that the string
pushes the switch at the end of every swing. If you get the mechanics
right, then the switch should work for at least 50 pendulum swings before
the pendulum doesn't swing far enough to push the switch.
Then, when you want to start counting, press: 1 + + on the calculator, and
start your pendulum going.
It worked for me!
This is a lot easier than designing circuits for debouncing switches,
decoding binary, etc.
Ben
>Hi there, List.
>
>My physics teacher is giving us an assignment to find acceleration
>due to gravity by using a pendulum. I was trying to think of a
>counting mechanism, but my limited electronics knowledge stopped me.
>I was wondering if anyone had some kind of circuit that could could
>start and stop a count activated by touch sensors. Any Circuits or
>diagrams would be appreciated.
>
>Darcy Dueck
>
>P.S.
>Turtletek, I hope your turtles are doing fine...
>I just had a goldfish that died and another jumped out of the tank a
>week ago. sniff. There goes C$1.10
>I'll shut up now.
>
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