Is ringing voltage dangerous?

From: Don Maslin <donm_at_cts.com>
Date: Mon Feb 28 19:13:22 2000

On Mon, 28 Feb 2000, John Wilson wrote:

> On Mon, Feb 28, 2000 at 08:55:33AM -0700, Richard Erlacher wrote:
> > The ringing voltage is over 250 volts peak-to-peak but at a high enough
> > voltage to make you jerk your hand away if you touch it. The voltage range
> > that's most dangerous is from 25volts to about 60 volts, as it won't make
> > you jerk your hand (or other body part) away, yet it is capable of
> > disrupting normal operation of the cardio-vascular system.
>
> I guess it depends on a lot. When I was in 6th grade I tried to build my own
> inverter, using a 12V lantern battery and a buzzer in series with the secondary
> of a doorbell transformer. Didn't get 110V like I was hoping but it gave
> off a nice 50 V according to my voltmeter (the finest that $8.95 would buy
> at Shack!). So being the well-adjusted, popular kid I was, I installed the
> whole mess in a lunch box and went to school and zapped everyone who didn't
> jump out of the way fast enough! No real ill effects (well I think I got
> punched a few times for some reason, but that's different), but I suspect the
> key was that it was probably a pretty low duty cycle, and more importantly
> I used a normal 110V cord and plug for the 50V end, so it was being applied
> to only 1/2" of skin, as opposed to going in one arm and out the other etc.

All of this reminds me that when I was in high school there were a few
of us that did some similar type things with a Model T spark coil - the
old buzz box thing. We made a haywire installation in a car with the
high tension lead connected to the car's bodywork and a ground lead
trailing on the pavement or ground. Power to the thing was controlled
by a push button switch.

It was rather fun - we thought - to wait until someone placed a hand on
the bodywork or, better yet, parked their fanny on a fender. The rest
is left as an exercise for the student.

But, even better was to ease up behind another car until bumpers touched
and wait until the driver returned to board and was about to touch the
door handle. ZAP!

We did not continue too long as word spread rather rapidly! Oh yes,
there was also the dog that elected to relieve himself on one of the
wheels...

                                                 - don

> Naturally my friends (the few I had left after that) wanted in, so they
> put together high voltage lunch boxes too. One friend's father worked for
> an electronics company (General Scanning in Watertown, MA, I never really
> understood what they make though) and used to hang around there after school,
> and one of the engineers liked the idea and put together a little transistor
> inverter circuit for him which got 170 V instead of 50. The engineer wisely
> put a big series resistor on so no one got hurt by that either, it bit a lot
> harder though, and the kid was able to fool people into getting into range
> because at least *his* lunch box wasn't loudly buzzing!
>
> Anyway in retrospect, this was all insanely dangerous, because it *really*
> depends on how good a connection you get, how dry the person's skin is,
> whether they have any unknown heart problems, etc. I've *heard* that it's
> possible to build up a resistance to this kind of thing but that sounds
> pretty fishy to me, it's not that kind of thing. I think it's more just
> hit and miss, I've zapped myself with all kinds of voltages as I'm sure
> most people on this list have, but still you occasionally hear of someone
> being killed by some pitiful amount just because it caught them the wrong
> way.
>
> Did anyone see the tape a few months ago on 60 Minutes or Dateline or whatever,
> showing the two founders of a company that sells "air tasers" demonstrate
> their supposed safety by shooting each other with them? I was impressed,
> it looked a no-kidding-around shock... And the needles have gotta hurt too,
> unless I misunderstood that part. I assume it's high frequency or uses short
> pulses or something though. And the nice thing about small shots of really
> high voltages is, charred skin doesn't conduct nearly as well! Built-in
> fail safe system... well maybe not!
>
> John Wilson
> D Bit
>
Received on Mon Feb 28 2000 - 19:13:22 GMT