EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: shane_95 on July 08, 2012, 04:54:22 pm
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Is there a way to get high volts and very low amps?
I want to have a bit of fun with high voltage but I want low amps so I don't kill my self.
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Plasma globe. Can bite though.
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Is that one of those things that has the glass do e and when you put your and on it, purple arcs go nuts
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That is right, buy a cheap USB or 12V powered one, and leave the globe on, it will act as a high voltage resistor. If you remove the globe the output is going to hurt.
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I want to some how make the circuit, I have a 240v to 9V 1A. Is there so,e how to step,up the volts and lower the amps?
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hm, we seem to have a plague of people wanting to kill themselves this weekend. If last week you were asking "how to charge a capacitor" and now you want to play with high voltages. 50V kills, 30mA kills ! if anything buy something pre-built.
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Shit, wow. It doesn't take much, some of the led's I have draw enough mA to kill me 3 times, then with my bad heart, even more :-\
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Shit, wow. It doesn't take much, some of the led's I have draw enough mA to kill me 3 times, then with my bad heart, even more :-\
Er, no. It seems you haven't been reading theory.
Unless the frikin' led's are drawing 200V, no.
hm, we seem to have a plague of people wanting to kill themselves this weekend. If last week you were asking "how to charge a capacitor" and now you want to play with high voltages. 50V kills, 30mA kills ! if anything buy something pre-built.
at wet skin resistances are about 10k which means about 5mA at 50V ... not too much of a shock
Dry skin resistances mean about 1meg maybe, 1meg at 200V is 0.2mA
now ... wet is where it gets bloody dangerous at 20mA
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The theory goes like this: the human body is considered to have a resistance of 1K (usually with regards to mains voltage AND frequency). it takes 40-50mA to kill you stone dead. 1K x 50mA = 50V !!!.
If you want to play with high voltage make sure you actually know what you are doing because we can't help after your dead and it only takes one mistake. I have had an RCD save my life before and they cut at 30mA and believe me it hurt and left me very shocked.
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I'm now confused, I'm going to bed, it's 5 am here
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The theory goes like this: the human body is considered to have a resistance of 1K (usually with regards to mains voltage AND frequency). it takes 40-50mA to kill you stone dead. 1K x 50mA = 50V !!!.
If you want to play with high voltage make sure you actually know what you are doing because we can't help after your dead and it only takes one mistake. I have had an RCD save my life before and they cut at 30mA and believe me it hurt and left me very shocked.
OH right, didn't know that it can drop to 1k with frequency but i still think you mean WET
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I'm not sure and it's only a guideline, babies will be less, old people more, no one is the same but from memory 1K is the figure used in explaining what voltage you need to kill yourself with if your really intent on doing so like some people here.
Frequency has other effects, I hear tell that at higher frequencies you get off more lightly as the current does not go through you but over your skin (so not through your heart) but I'm no expert and I don't deal higher than mains and treat it will more respect than any god !
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240v ac and 380V ac is not that bad , it tickels ^^ .
Use an 555 timer + mosfet + ignition coil + dc source
Up to 3 Kv verry low current. nice sparks and won't kill you to fast ;) .
TheSignalPath has an video about it. I did it myself , it does not hurt.
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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)
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240v ac and 380V ac is not that bad , it tickels ^^ .
Use an 555 timer + mosfet + ignition coil + dc source
Up to 3 Kv verry low current. nice sparks and won't kill you to fast ;) .
TheSignalPath has an video about it. I did it myself , it does not hurt.
You are wrong there, 240 volts off the mains is a very nasty buzzing sensation 415 feels about ten times worse and throws you across the room, I know this from first hand experience. Nine thousand volts at high frequency makes you feel as if the bones in your hand have been ripped out and then put back again, well that's the best i can explain the experience. i got that when I was setting up a mains operated electric cattle fence and when I went out to test I was walking and talkin at the same time and walked right into the fence at the point where the feed came, Not as bad as a friend of mine having set up his sheep fence he got called short and forgot that the fence ran just where he was having a piss, He jumped so high that it must be an Olympic record.
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240VAC is, if you'll pardon the pun, quite shocking. And fully capable of killing you very easily. Been there, nearly done that, will not be repeating the experience for fun.
415VAC sucks horribly and can kill you if you look at it funny. It's far more dangerous than 240V. There's a very good reason you don't place two socket outlets on different phases next to each other.
340VDC (a charged cap from 240VAC) feels like you're being stabbed. With red-hot sowing needles. Don't play with capacitors.
Do not play with high voltages unless you know exactly what you're doing and have at least one person on hand who not only knows what they're doing, but knows CPR.
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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
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Like many (most?) people on the forum I've had a few 230V AC or couple-of-hundred volt DC shocks and lived to tell the tale. Once, in my 20's I remember feeling quite pleased that I'd fixed an old valve amp without zapping myself. Finishing off I noticed that the mains switch was loose so reached in to tighten the retaining nut......
It wasn't switched on or plugged in so I think it was one of the paper caps but it hurt like hell.
Now I'm a bit older and a bit more cautious I realise that each shock was a lapse in concentration that could have killed me - it takes very little energy to induce ventricular fibrillation if it hits the heart just right.
In cardiothoracic theatre they use tiny little paddles and one or two Joule shocks to defibrillate directly on the heart - compare that with the 150-200J energies that external defibrillators use. The bottom line is that you can affect the heart's electrical activity with just a few 10's of volts and a few 10's of milliamps in the right (wrong?) circumstances. Much of the time dry skin, imperfect contact and a current path away from the heart limit the damage but do you really want your life to depend on that much luck?
Don't fuck with electricity, small amounts can kill and large amounts can kill with a vengeance.
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One time my hand was on a conductor and my other hand on the gnd of my moped running stationary around 6000rpm.
The voltage was around 10Kv if i remember correctly. I was the conductor for a few seconds. It all went trough a big blood vein in my arm. The vein was all swelled up and red for a few days and my hand was also num for a few days. I felt the pulsing in my hart but i survived ...
now i'm thinking i had some hart arrhythmic problems at random times a few weeks later :X , now i just realize why ...
So ... i guess don't don't any of the things i just described.
yay i'm still alive =)
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G7PSK,
a cattle fence wont kill you because it's designed not to, from memory the international max voltage is 10,000v on an electric fences but they are very low amperage therefor it'll 'zap' you as it pulses but wont kill you
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Can we stop arguing and agree that over 50V *might* kill if the current is over 20mA.
Electric shocks are not something where you can point and say "That will kill you stone dead" or "That's safe"
People out at sea have died from 48V due to the salt water decreasing their skin resistance. And people have survived a direct lightning strike to the head.
It's not something you can label as either lethal or safe because there are so many factors
- Everyone has a different skin resistance
- The resistance in the path to earth when you receive a shock varies depending on the situation.
- The path the current decided to take through your body isn't predicable
- The skin effect (if the frequency is high).
- The condition of your heart
- The time you may/maynot be in contact with the voltage.
I could go on...
So basically.. No one is ever going to recommend you play with high voltage!
If you have a weak heart don't play with high voltage at all.
If you're healthy and insist on playing with it then a car ignition transformer is a relatively safe place to start.
(that's not to say a bizarre/freak encounter with an ignition transformer couldn't kill someone, it's just highly unlikely, statistically speaking)
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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.
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G7PSK,
a cattle fence wont kill you because it's designed not to, from memory the international max voltage is 10,000v on an electric fences but they are very low amperage therefor it'll 'zap' you as it pulses but wont kill you
I never said it would kill, In the UK the pulse must be kept below 15 joules and as it is HF you have the skin affect, all I said was that it is painful by trying to describe what it felt like to get such a shock, I know many people who test their fence by grabbing it, not something I would do as I cannot stand the horrible sensation.
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Ohm's Law always applies in these situations.
Any voltage/current source looks like a perfect voltage source with an internal resistance.
The 240 volt mains supply has a very low internal resistance,so can source a great deal of current .
If you are across the mains,the circuit consists of V( supp) which is the perfect source, in series with R( int) & R (you).
In the Mains case R(int) is sufficiently low that it can be ignored, so the total current is very close to I= V(supp)/R (you)!!
For 240 volts,that is effectively 240/R(you).
In most really high voltage power supplies that Electronics people play with,R(int) is no longer negligible,so any attempt to draw enough current to kill you causes the output terminal voltage to fall to a low value,limiting the possible current.
It will still "bite" though!
WARNING! WARNING! Will Robinson!!
(1)Large capacitors may be charged to high voltages in some circuitry.
The internal resistance of capacitors is very low,so they can deliver a dangerous shock,both when the device is operating,& immediately after turn off!!!
(2)My comments about high voltage power supplies earlier,DO NOT apply to the power supplies commonly used for tube type Radio RF Power Amplifiers.
These may be intended to supply 2kV or more,at several Amps to a power Vacuum tube.
To do this,they need a very low value of R (int).
From our above discussion,you can see where that leaves you! :o :o :o :o
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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.
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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 !
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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! :D (red quote above) ok right! you can die! (even in your sleep) ;) hands off.
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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 :)
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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...
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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.
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... 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
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... 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 ! ;)
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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 (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/ (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).
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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)
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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.
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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.
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the resistors could break down and BANG
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The safest way to play around with very high voltages is with LTSpice ;D
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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 (http://openbookproject.net/electricCircuits/DC/DC_3.html)
You life might depend on it.
Cheers,
Florian
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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
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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
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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)
Static Electricity demonstrations (https://www.youtube.com/watch?v=QxZ6AWLpnUw#)
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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.
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You obviously have to keep the capacity low.
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You can try this......
http://youtu.be/B4YKkCy-pGE (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.
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You can try this......
http://youtu.be/B4YKkCy-pGE (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
https://www.youtube.com/watch?v=KSlQjw9OPG4#ws (https://www.youtube.com/watch?v=KSlQjw9OPG4#ws)
Skip to 1 minute 40 seconds
https://www.youtube.com/watch?v=327eDUluub4#ws (https://www.youtube.com/watch?v=327eDUluub4#ws)
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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.
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Nice is that any open led will not stop it from lighting the rest for long.
hehe
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I see The Boden even reaches the far off lands of Australia and New Zealand.