Alt-BEAM Archive
Message #03046
To: NSX - evenflow88@hotmail.com
From: "Jesse D." smokin@n-link.com
Date: Thu, 06 May 1999 13:50:01 -0500
Subject: [alt-beam] Re: HYPER WALKER 1.0
NSX - wrote:
>
> Hie,
> i while ago i mailed mark asking bout his particular robot ...it is
> actually a windup toy being modified as a robot which uses frequency to
> detect motion/object...but the bad thing is...i dont have a clue how to draw
> the schematic out based on his text like below and most of all i dont have
> the getting started in electronics book by radio shack..sigh* so i hope u
> guys could help me out
>
Here goes my best "Simplified description" (May still have to much
Jargon for you..)
OK what I think Mark here is talking about is a circuit that detects
disturbances in the ambient 60Hz hum that comes from normal AC power
wiring. Standard AC power "Switches" between + and - at 60 times per
second, which creates a detectable hum. What he used was a simple
crystal radio reciever which is basically just a germanium diode, a
capacitor and a coil (To form the tank circuit which demodulates the
60hz electro-magnetic hum) and an antenna to pick it up. To the output
of this basic RADIO reciever he used a circuit which looks at the signal
so many times a second, and compares it to the last time it checked, so
that when the signal changes (compared to the last time it checked) it
outputs a logic signal. Now what that would accomplish is a detector
circuit that senses change in the "Environmental" 60Hz field which is
just about everywhere. When something moved close to the antena of this
unit, say a CAT or a person, the reciever would sense a change in the
field and trigger the bot to move. Basically it sits there doing nothing
until the cat walks by and then it jumps around, therefor "Scaring the
cat"...
> Mark's text:
>
> Hi. the ambient 60Hz cat detector used a standard crystal radio reciever
> hooked up to an amplitude modulated sample and hold. The bottom line is
> that, inside a house with conventional wiring, any disturbance in the
> percieved field would result in a spike that could enable movement. The
> circuit was not BEAM but one I got from the radio shack "Getting Started in
> Electonics: radio Circuits" series availalbe at most radio shacks. Both
> zoidwalker and the cat-scarer were retrofits to wid up machines done in the
> 80s. Very old and very primitive.
>
> Check out those books for circuits. Good luck.
>
> markt.
>
> ______________________________________________________
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--
__ __ Jesse C. Druehl __ __
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