Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mgm.mit.edu!wolfgang
From: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Newsgroups: sci.electronics
Subject: Re: shock box
Message-ID: <3616@bloom-beacon.MIT.EDU>
Date: 10 Mar 88 02:51:18 GMT
References: <307@trwind.ind.TRW.COM> <4881@videovax.Tek.COM> <1231@uop.edu>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Organization: Freelance Software Consultant, Boston, Ma.
Lines: 34

I wasn't going to post any shock-box articles. They're certainly fun
to joke and think about, but I have real reservations about their
safety.

Back 16 years ago (when I was 1/2 of this age, damn!) I built a very
simple relaxation oscilator, dc to dc step up box. It used a 45v
photo-flash battery, an rc filter, and an scr with a 40 volt diac
triggering it. The transformer was a 2" xenon tube ignition
transformer which put out ~2kv. I rectified the output of this with a
few series 1kv diodes, and stored the charge on a few 0.1 ufd caps,
chosen for their low leakage. The intention was to have a very high
efficiency device, the size of a pack of cigarettes, that could run
for *many* hours.

As a shock-box this was a great success. Anyone that got shocked was
the greatest evangelist for finding the next sucker to receive a jolt.
The box always drew quite a crowd of spectators.

Although the box only packed a small charge,

	Joules = 1/2 Capacitance * (Volts ** 2)
	(* 0.5 0.5e-6 2e3 2e3)
	1.0 joule

four people (out of tens shocked) asked me days later, if I thought it
was possible that the box to cause back pain. I thought nothing of it
at first. Then it dawned on me that each of these four people had
received jolts from on hand to another. Hmm. That got me worried.  I'm
just glad that nobody had a weak heart. Nothing like someone keeling
over to turn the tables on the joke...

Wolfgang Rupprecht	ARPA:  wolfgang@mgm.mit.edu (IP 18.82.0.114)
326 Commonwealth Ave.	UUCP:  mit-eddie!mgm.mit.edu!wolfgang
Boston, Ma. 02115	TEL:   (617) 267-4365