MacGyver

<chuckle> I hate to rain on your parade twice in one day, but that's not an accurate statement, either

While it's usually the higher amperage that kills you, high voltage can do just as much damage (just in a different manner). We owe our ability to touch both contacts of our car battery to the high resistance of our skin (in the 10's to 100's of kohms range). However, two sharp contacts piercing the skin on fingers of opposite hands will allow up to several amps or more to travel through the chest... stopping your heart in its tracks. Low voltage, high amperage, bad idea.

A high voltage, low amperage signal can be beneficial when applied in the correct manner... prime example there would be a heart defibrillator. But as the voltage goes up, you create the ability for the power to ionize air (you've seen static electricity jump from your fingertips, right?). Get the voltage high enough and just a litle bit of current, suddenly you can do some nasty tissue damage. You can vaporize water in the skin and literally blow a limb apart from the inside (lightning is one such extreme case, though that's high current in addition to high voltage).

Tesla coils are of the "air ionizing" type of project. Those "hair raising" deals where someone touches a silver ball with one hand are nothing more than high voltage (but very low current) generators. In those cases, you stand on a rubber mat (or other insulator), forcing the electricity to leave your body by any way possible (in the case of hair standing on end, it's attempting to leave the tips of each hair strand and forcing them apart like similar magnets).

Shocked the crap out of myself with quite a few Tesla coils in the past, but as you can see, I'm still here... BTW, Tesla coils are high voltage, fairly low amperage, but will gladly leave a nasty burn (and an eye twitch that seemingly never goes away ).

darkknight1999

jwa4378

What I was referring to was something like a Tesla Coil providing HIGh voltage, but low amps, like you stated. The human body acting like the wire, or the conductor. I saw something on "Mythbusters" - (a poor reference, I know) - where they created an 8' tall Telsa Coil and ran 24,000 volts through one of the guys. No damage. But pretty damn cool looking.

So I deduced that High Voltage / Low Amperage (which I assumed speaker signals were) will cause no damage to the conductor (human or wire). I did not take into account the impediance of the conductor (again). I assumed that amperage was a set number, and not variable based on the impediance of the conductor.

I did not know that the amperage through speaker wires was that high....

How many amps will it take to kill a man? I have been popped several times by 110V / 20A circuits while wiring homes (accidentally brush neutral wire while working on the hot one). Just a BIG jolt, some squeezing of the fingers, and a DAMN good wake-up call.

Anywho.......Electrical Engineer seems to be your area (as you are one). I think I will go back to Accounting Project now.... .

John

MacGyver

That depends on a number of factors, but a direct shot into the bloodstream it's been suggested that it only takes a handful of milliamps... say, much above 10mA and you'll be looking for an ER. Much above 100mA and you'll most likely be looking for a mortician.

If we're talking about a shot to the skin (you touch a wall circuit), we can survive a heck of a lot more due to the resistance of our skin (current equals voltage divided by resistance... high resistance skin, so low(er) current). Things get more dicey, though, when the path of current flow is across our chests, like when you grab a different power line with each hand.

darkknight1999

I don't recommend trying it to see....

PJK3

regretfully, i've seen a safety video of this happening to someone, as well as met some people who have survived this...

*shudder*

*shudder*


John - looks like we need to get you a copy of Ugly's Electrical Reference. (actually, if you can find one at Barnes and Nobles or such, it is generally pretty cheap. (ISBN 0-9623229-2-X by George V. Hart) i don't know what mine cost b/c it was given to me by a vendor. if i get a 2nd one ever, i'll send you it.)

still, since you're an accountant i'll trust you know some math.

there are really only a few governing equations for most basic electrical needs. once you know those, a lot of the basics can fall into place.

Power = P
Votage = E
Current = I
Resistance = R

R = E / I

P = E x I


substituting those two gets you quite a number of combinations:

R = P / I^2 = E^2 / P
E = R x I = P / I = sqrt(P x R)
P = R x I^2 = E^2 / R
I = sqrt( P / R) = P / E = E / R


for resistance loads:

Resistance in parallel: 1/Rt = 1/R1 + 1/R2 + 1/R3 + ...
Resistance in series: Rt = R1 + R2 + R3 + ...

in series:
the total voltage equals the sum of the voltages through all the loads (resistors), the current is equal through each load.
the distribution of voltage is proportional to the resistance of the load.

in parallel:
the total current equals the sum of all the currents through all the loads, the voltage is equal through each load.
the distribution of current is proportional to the resistance of the load.

jwa4378

Good to know. Yeah, now that I remember it, Mythbusters also did a show on how many milli-amps it would take to kill, or severely maim someone. They had a ballistics gel human that they set in a tub of water, then dropped random appliances (with different draws) into the water. I think they said that 300 milliamps could kill / severely harm someone.....I should look that one up again.

Yeah, I was an Electrical Engineering major for 1 semester......then I decided I didnt like looking at formula's all day . Now I just count money!

John

MacGyver

I'd be interested to know what their setup was... ballistics gel by itself isn't going to tell you anything about what's necessary to kill. For that, you need an actual heart/body (or at least an accurate simulation of one). Ballistics gel will give you physical evidence, such as trauma, not physiological evidence... they could show what would happen if the internal water vaporized, but not show how little is needed to stop the heart or shred a muscle. Obviously they had some sort of instrumentation in there, but I can't imagine what kind to get useful data.

JAPCAB

JWA-

Yes the amp is getting power. the green light comes on and stays on. no blinking lights.

I have checked the amp sub wire connection, the connection onto the sub box and even took out the sub and checked the wiring onto the sub/inside of the sub box. A few were loose but nothing disconnected.

The wires are not soldered.....perhaps i should ask for this to happen thanks for the tip.

I have checked all the wires etc, but without a multimeter its impossible to tell where the break is. I checked the headunit, it is connected and should be sending a signal to the amp without doubt. the sub wire into the amp is secure as hell. The part i doubt is the connection onto the sub box and perhaps the internal sub box connection. i had a bit of a look but coulnd't find the problem.

When the sub stopped working the bass just stopped. I have heard sometimes when subs blow they make quite a bit of racket, mine didnt do this luckily.

I'm taking it to the shop for new tweeters and retune on thursday, i'll get them to fix up the sub at the same time. I understand connections etc get loose but this system has been a pain in the bum. I've had it one week and already had two/three problems with it. Oh well as long as they fix it and warranty it which is what they will do then i dont have a problem.

Yeah i was lucky with the soundstream rep too!

JAPCAB

hehhe

i dont have a multimeter......can i test to see if there is a signal coming thru the wire by putting the wires onto my tongue or teeth??

lol