Re: Shockers...

["Prof. John P. Ertel (wizard)" <jpe@nadn.navy.mil>]

On Wed, 12 Feb 1997, Dwight K. Souder wrote:

> 	Greetings everyone!  A student asked me a question that I wasn't
> sure of, so I thought I'd pose the question to the rest of you.  One of
> my students was asking about a practical joke device that looks like a
> regular book, but when you open it, it gives the holder a jolt.
> 	I'm not sure what he's talking about (yes, I live a sheltered
> life), but my guess is that it is either a "joy-buzzer" device which
> doesn't really shock but vibrates or something that has a capacitor in
> it.
> 	Does anyone know how these books work?  If it is a capacitor,
> isn't it dangerous to use such a device?  I know the capacitors in tvs
> and some old radios have enough "juice" in them to melt a screwdriver
> when placed over the terminals...yes, I know from experience when I was a
> kid.  :-)  What type of capacitor is being used?
> 	Hmmm...maybe I should attach a few of these to the magazines I
> see kids hiding behind their textbooks, when they should be studying. 
> > :->
>
> Dwight

I know of two such devices.  The first one I have never tried as I had
trouble figuring how to do the requisite switching.  It was described in a
flyer that I saw in a JOKE STORE when looking for "disappearing ink" for a
chemistry demonstration that I was doing many years ago. The flyer called
for 6 capacitors and 6V worth of batteries.  It went on to say that one
need only charge the capacitors in parallel and then rig a switch to
change them to series when released as you hand the container holding all
of this to a friend(?).  As I said, I never figured how to practically
accomplish the switching.  Also, my simple minded thinking only comes up
with an "output" of 36V (6V * 6 caps), and this is hardly enough to be
SHOCKING.

On the other hand, you could take an old automobile ignition coil and
connect its "input" or primary leads in series with the same 6V battery
and a (normally open) momentary switch.  The "output" or secondary leads
are then attached to two contact points that your friend(?) might grab
when handed the box.  (NOTE THAT THESE "OUTPUT CONTACTS" MUST BE INSULATED
FROM EACH OTHER)  Now if you press the momentary switch, you will energize
the coil causing a fair current (even at 6V) and a reasonable magnetic
field.  If you let go of the switch as your friend(?) grabs the device any
where near the output contacts, the collapsing magnetic field will induce
a substantial voltage across those contacts and your friend's hand.  While
down by a factor of 2 from the spark (at 12V) in your car, the "jolt"
should get anyone's attention!

My only question is why would one ever do this to a friend?!

ERTEL SENDS.         _____________________
                    / Prof. John P. Ertel \
                   /   jpe@nadn.navy.mil   \    
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