High volts, low amps

[Simon]

I'm at the point now where I say: let natural selection prevail. If after being warned one wants to kill ones self, well - natural selection should be allowed to have it's way !

[Mechatrommer]

If you are a beginner, do NOT open up mains powered equipment, do NOT play with mains voltages (plugs into the wall), YOU COULD DIE.
You need to study up on your electronics theory, you have to do a bit of maths but it is fun and easy, don't skip the maths.

but you will lose the FUN of it! (red quote above) ok right! you can die! (even in your sleep) hands off.

[M. András]

240v ac and 380V ac is not that bad , it tickels ^^ .

You are very wrong ! 240V kills ! and you are talking to a beginner here. Indeed the ignition coil project is far safer (at your own risk)

i accidentaly touched the wrong end of a live 230V ac switch with 1 hand 2 fingers, it feels like hundreds of little bugs+shaking in the same time, and here i am 10 years later, i would not poke in a box with blindly again thats for sure

You're still alive because the current didn't go through your heart.

When working with high voltage that's the main thing to remember: Don't get in a situation where the current could go through critical parts of your body like heart and brain.

...and if you want to play with "safe" high voltage (at least to humans), try out those experiments that involve static electricity. Those can produce voltages in the 15-20kV range. Just stay away from anything flammable.

i agree on that, it was goung trough my 2 fingers next to eachother, i was on a wood bad

[Kremmen]

Anyone who thinks mains voltages are anything to carelessly play with may want to reflect on this:
Long time ago as a young EE i used to work for Stromberg, now part of ABB. While debugging the controls of a big 3 phase frequency converter i needed to measure the mains supply whether it was there or not. It was late, i was tired and the measuring gear was not what you would call safe today - an analog Metrix multimeter with no safety plug wires. So my fingers slipped and i ended getting full 400 volt mains righteously from one hand to the other.
Let me tell you it was like being struck by lightning. It was instant lights out and judging from the chaos in the lab i sailed over the workbench at some speed. Waking on the floor a couple minutes later the heartbeat felt decidedly funny and i did not feel at all like getting up. Took quite some time to get on my feet and and more than a week to raise my arms above shoulder level. All the joints were stretched to near breaking point at the time. Also funny that i have never been able to recall the last couple of minutes before the zap. Must have been some kind of brain reboot. However, looking at the fingers it was obvious which way the current went - there were small but clear burn marks in the fingers of both hands, like pressing your digit on a hot plate for a moment...

So anyone tells you mains voltages are harmless, do understand it is dangerous bullshit. Even the household current will effortlessly get you if you manage to hook yourself as part of the circuit.

While working at Stromberg i got to see and visit places not seen by just everyone and occasionally saw what high voltages and currents can do. Sometimes you don't even need to get an actual shock. It might be enough to stand too close to a high voltage short to buy the farm when stuff starts flying at high speed. Seen brick walls crumble and fly like deer shot when a high power breaker fails; seen bones break when guys stand in the way of grounding cables and some moron engages the 25 kV disconnector...

I decided not to win the Darwin award, at least not this way. So in addition to care and respect, isolation transformers rule in my workshop...

[Psi]

While debugging the controls of a big 3 phase frequency converter i needed to measure the mains supply whether it was there or not. It was late, i was tired and the measuring gear was not what you would call safe today - an analog Metrix multimeter with no safety plug wires. So my fingers slipped and i ended getting full 400 volt mains righteously from one hand to the other.
Let me tell you it was like being struck by lightning. It was instant lights out and judging from the chaos in the lab i sailed over the workbench at some speed.

My dad once told me of someone at his work who tried to lift up some CRT monitor. It was still plugged in and his hands touched 400V DC on the back.
His muscles contracted so quickly he threw the thing over his head and right across the office at superhuman speed.

[digsys]

... he thew the thing over his head and right across the office at superhuman speed.

Superhuman you say !!?? ... superhero?? ... hmmmm .. I have an interesting idea

[Simon]

... he thew the thing over his head and right across the office at superhuman speed.

Superhuman you say !!?? ... superhero?? ... hmmmm .. I have an interesting idea

Oh no you don't ! 

[rsjsouza]

Back to the original poster's question...

One of the "safest" (if such thing exists) methods to generate high voltages is to use a voltage multiplier with beefy resistors (10M+) at the end. More like an air ionizer.

A bit of theory:
http://www.onegentleman.biz/Hardware%20Design/High%20Voltage/High%20Voltage%20Circuits.html

And an interesting assembly:
http://www.instructables.com/id/How-to-Make-a-Negative-Ion-air-ionizer/

The generator itself will not make half meter sparks, but it will be interesting to look in a dark room and is capable of glowing neon lamps from a distance.

However, always keep in mind everything previously said in this thread regarding safety and the effect of high voltages in your body. I myself got shocked several times throughout my life and can attest this is no joke. Also, when dealing with high voltages keep in mind the electrons are very narrow and not only find their way through the smallest gaps (invisible holes in pliers' insulation) but can also "jump" great distances (especially if you are using thin insulation).

[Psi]

One of the "safest" (if such thing exists) methods to generate high voltages is to use a voltage multiplier with beefy resistors (10M+) at the end.

A few 10+ meg resistors on the end may limit the current to safe levels and let you touch arcs from the output but it's still dangerous because high current is available before the resistors.

It's a similar thing with small Tesla coils, the many thousands of volts out the top is normally quite low current and high frequency, so isn't overly dangerous.
But the high voltage on the input side is a different story, 50Hz 120mA at 15kV, which is very dangerous.

(Note: some coils are different and the arcs out the top are nasty, they can give serious RF burns and can be high current too. Never touch a tesla coil)

[rsjsouza]

A few 10+ meg resistors on the end may limit the current to safe levels and let you touch arcs from the output but it's still dangerous because high current is available before the resistors.

Well, I wouldn't touch the output in any case...

Even still, the available energy just before the resistors is severely reduced by the network or resistors and capacitors - especially if you choose small capacitors (1nF or less). A Tesla coil, on the other hand, is way more efficient in transfering energy to its secondary and therefore it produces higher energy sparks.

[Psi]

yeah, i agree.

I just wanted to get the point across that making the output of something safe to touch doesn't nessesarily make it safe to work with.

[Simon]

the resistors could break down and BANG

[PeteInTexas]

The safest way to play around with very high voltages is with LTSpice 

[LEECH666]

Shane, I wanted to tell you this before, but I always stopped myself from doing so because of the sheer amount of helpful answers you always got with your topics, but this time I feel like posting this is necessary:

You really should start reading and understanding a bit of basic theory.

For example go start reading about ELECTRICAL SAFETY here:
http://openbookproject.net/electricCircuits/DC/DC_3.html

You life might depend on it.

Cheers,
Florian

[shane_95]

As cool as throwing something across the room with superman strength sound, after reading all this, my 9v transformer will do just fine.

Before people go off at me for playing with main's voltage, it had all the leads hooked up for it, and thanks to digsys and his kindnees, i was able to hook it up to a bridge rectifier and run my DC things now

[M. András]

you can go and google the physical effects of electric current trough the human body, alternating current(AC) has a lethal side effect, direct current(dc) has another lethal side effect, so just be careful

[KedasProbe]

A pity that the dead people can't tell about their experience to help you understand the danger of high voltage electricity.

Try playing with static electricity a bit. low capacity and also interesting. (rubbing things together)

[G7PSK]

Static can hurt too, even kill. I used to have a Chrysler PT cruiser that gave me so many painful shocks from static that I got rid of it. Lightning is static and that can kill and do enormous amounts of damage and you don't need lightning for dangerous levels of static, I have seen fires started by static build up on conveyor belts and by ropes on winding gear as well.

[KedasProbe]

You obviously have to keep the capacity low.

[SeanB]

You can try this......


http://youtu.be/B4YKkCy-pGE

Note that this one I did today is not going to shock you, more like kill you, if you touch it when on. I unplugged every time I adjusted it.

[Psi]

You can try this......
http://youtu.be/B4YKkCy-pGE
Note that this one I did today is not going to shock you, more like kill you, if you touch it when on. I unplugged every time I adjusted it.

What current limit does that NST have?  If it's just a 30mA NST then you'll likely survive an encounter with it.
It's only 10mA over the 20mA considered to be *able* to kill.

Where as a 230V (hand to hand) would flow around 150mA through your body.

Here's some info on NST safety.

skip to 2 minutes  29 seconds


Skip to 1 minute 40 seconds

[SeanB]

Only 30mA 7500V. i have 2 15kV units as well, this one was just the closest to hand, and I wanted to test it, as I had just picked it up for free.It will theoretically light up 2 series strings of LED's that consist of 2500 led's per string, with each string being in anti parallel. Nice is that any open led will not stop it from lighting the rest for long. 225W of power is a lot when it is in a concentrated arc, the little brass brazing rods get very hot after a few minutes of running.

[Psi]

Nice is that any open led will not stop it from lighting the rest for long.

hehe

[Monkeh]

I see The Boden even reaches the far off lands of Australia and New Zealand.