On Mon, 28 Feb 2000, Richard Erlacher wrote: Over the years BYTE, PopularElectronics, RadioElectonics and many texts (none I have) have covered it. the key element is NOT Voltage but, the current flow it can induce through a largely resistive body. The currents range from about 60MA (considered deadly if across the chest) to 20uA which is down around the threshold level. Also DC vs AC and what frequency the effects vary. HF(above several MHZ) AC for example is more likely to cause burns before muscle spasms. RULE 1, unless the voltage is very low it _can_ be dangerous. Low is hard number be exact about but, over 12-30V is the watch out zone. RULE 2, All efforts are to be made to avoid crossing the heart or chest as a possible path for safety. One hand in pocket rule is derived from this. RULE 3, if you not sure, make sure. get a meter and find out if it's live and how hot hot is. Over the years working with RF and transmitters I've been hit with RF and DC to 1800V (ouch!) and LF AC power to 200V/400hz. Some were annoying, a few painful, one nearly bluecrossed me and the better ones left scars (and a willingness to NOT stick fingers in). Allison

On Mon, Feb 28, 2000 at 08:55:33AM -0700, Richard Erlacher wrote: 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. 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