Build a simple Marx Generator
10 Steps
Do you like the idea of tesla coils and other high voltage sparking stuff, but don't have the time, money or patience to build something that is elaborate?

Well, here's a fun 'n' simple project that can make big, fat, noisy sparks at least 2 inches long, and can be built very quickly and cheaply. It might be even more fun to use a marx generator than using a 'very complicated to build' tesla coil!

And to let you know, this "Quick & Dirty" Marx generator website helped me a lot to build this marx generator.

If you have no idea what is a marx generator, you might be saying this in your mind "What the hell is a marx generator!", read about it here on Wikipedia.

WARNING! This project generates very high pulse discharge voltages, which can seriously harm and could be potentially lethal to you and others that are careless to touch the output of the marx generator.

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## Step 1: So, how does it work?

The Marx generator consists of an array of resistors, capacitors and spark gaps arranged as follows in the schematic...

The capacitors are charged up in parallel through the resistors, so they each become charged to the input voltage. When all of the spark gaps fires (sparks), the capacitors get effectively connected in series, therefor multiplying the input voltage by the number of capacitors and causing a long spark at the end of the marx generator.

Rb has a ballasting effect, it is used to prevent a continuous arc forming across the first gap - this prevents further firing of the marx generator. The value of the resistor will mainly depend on the type of power supply is used, in this case, we are going to use an 10M resistor for this marx generator on this instructable. However, you can reduce the Bb's value to try get more 'bangs per second' without causing an arc forming on the spark gap...

Now, you know how it works (I hope), so lets build it!
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twotower says: May 8, 2013. 7:48 AM
Thanks for your instructable! Since I'm still learning, I'm not up on all of the abbreviations. Can you please tell me what 'RB' stands for? Certainly not Rhythm & Blues...."humor"
Thanks!
my wookie says: May 2, 2013. 4:27 PM
just for fun and because i could, do you think a MOT would work to power it? figured id just ask if you thought it would be safe. (don't want to blow up a bunch of capacitors, not because i'm cheap, just because it stinks)
Lord Garon says: Apr 18, 2013. 9:27 AM
Guys, let me offer a little advice in the hopes of preventing unnecessary injury. I was an electronics technician in the military and maintained high power communications and radar equipment. I have received two serious shocks, both causing heart fibrillation and requiring emergency medical care. One was from a -350 VDC bias supply on a CRT radar display and the other from a +1800 VDC plate supply. Both were my fault and were caused by a failure to follow safety procedures which I was well aware of. (Okay, I acted stupidly.)

The worst case electric shock scenario involves a circuit completed through your heart via direct contact with blood in vessels. An unlikely event which would require piercing the skin at two points. However, the scenario shows how sensitive your heart is to electrical disruptions; a 1 milliamp DC current flow can initiate fibrillation and 10ma can be fatal (arrest). On a more realistic scale, I can personally vouch that a 350 volt potential across dry skin can send you to the hospital with a team of very worried paramedics. Of course, the current level is important, but if you can't compute the possible current flow, assume it is dangerous.

My advice: Reduce the chance of a complete circuit through your heart. How? Observe the "One Hand" rule. When working around an energized (or recently energized circuit with capacitors), put one hand in your pocket. The current path from fingertip to fingertip is across and through your chest. High voltage will find a way to conduct, regardless, and the One Hand rule is NOT a cure-all, but it is a good start for safety.

If you are not familiar with basic electrical theory and safety precautions, if you don't know WHY a circuit is either safe or dangerous, don't play with it. Period. I have a machine at home that will make almost as impressive a spark as this one and is electrostatic in nature (microamp currents from a PVC charging rod and a few water bottle/foil Leyden jars.) It HURTS, but I don't think it would kill me.

If in doubt, just remember that TASER guns run off batteries and people have experienced fibrillation and heart attacks from being tased. And TASERs are designed NOT to kill.

Sorry for the WOT, but it seems important to me.
ozzydogk9 says: Apr 15, 2013. 6:45 PM
To add to my pod racer, lol
endolith says: Jul 11, 2010. 7:27 AM

Can this really harm you? The idea that a special number of voltage or amperage will automatically kill you is not accurate.

Scuffing your feet across a carpet and touching something metal also produces thousands of volts and large currents, but it obviously doesn't harm you, because the capacitance is small and the spark is very short-lived. Yes, it's high voltage and high current, but the duration is less than a microsecond.

I'm sure it hurts, but I'm skeptical that it would actually cause any harm. How long are the sparks in cm?

10x 1 nF capacitors charged to 7 kV store a total of 250 mJ. Scuffing your feet across the floor stores maybe 60 mJ max by comparison.

"The effects of electrical current passing through the human body are covered at length in the International Electro Technical Commission document IEC 479-2:1987. In this document it indicates that a transient or capacitive discharge, as is the case with static electricity, requires energy in excess of 5 Joules (5000mJ) to produce a direct serious risk to health."
Mar 24, 2013. 4:56 AM
I saw on mythbusters that only a few milliamps across the heart will kill you.
endolith says: Mar 24, 2013. 8:00 AM
But how much voltage do you have to apply to your body to get milliamps across the heart? And how long of a duration does the current need to last to kill you? if it's 10 milliamps for 1 nanosecond I doubt it will do anything.
Plasmana (author) says: Jul 15, 2010. 8:08 AM
Okay, you made a very good point, can my marx generator kill? Very good question, personally, I will NOT touch it even if its safe. I never really understand Joules as they are many other units of energy related to it. Each capacitor (1nF) holds approximately 4kV to 5kV, how do I convert that to joules to see if its safe(ish) or not?
endolith says: Jul 15, 2010. 9:23 AM
I already did that for you, but I was using 7 kV. :) The energy stored in a capacitor is given by 1/2 * C * V^2, so:

1/2 * 1 nF * (5 kV)^2 = 0.0125 J = 12.5 mJ

Wolfram Alpha can do a lot of work for you:

capacitor stored energy 5 kV 1 nF

Multiply by 10 and you have 125 mJ total, which is 1/40th of the energy that document says is the minimum that will hurt you.

I'm not claiming that this thing definitively can't hurt you. I'm just skeptical that it's dangerous. Even if it's not harmful to health, the shock might still hurt like hell. :D
endolith says: Jul 20, 2010. 9:36 AM
For another example, I'm looking at a safety test certification document for EN 60065, and they limit the maximum energy of a discharge to 350 mJ.
endolith says: Jul 15, 2010. 9:31 AM
The total voltage could be 70 kV, which means the arcs should be able to jump about 1 inch. Does that seem right?
chakra says: Jul 13, 2010. 11:05 PM
WOW!! U sure R a expert on electricity!! where u got all those facts from??
endolith says: Jul 14, 2010. 6:43 AM
I'm an electrical engineer. :)
Mar 24, 2013. 5:01 AM
is their anyway i can salvage capacitors from various motherboards; and would it make a difference that they were all different.
lortech says: Jan 16, 2013. 12:24 PM
Is there a way to change the values so as to hold off on the charge jumping the gap...unless a conductive object passed across it?

Need to kill a mouse and want to let it wait, before stiking the mouse as it passed by :)
altrobot says: Mar 22, 2013. 11:28 AM
yes, just make the first spark gap slightly bigger than the arc can reach, then when you put a conductive object in between it'll arc over using the object as a stepping stone
softenersreviews says: Mar 2, 2013. 4:02 AM
That is so cool!!!!!!! You are very SMART =O
newnarutofan says: Jan 14, 2013. 9:26 AM
what is that thing in the first picture and how do i get one.
Eng Radwa Ahmed says: Dec 12, 2012. 8:24 AM
what is this in step 5
http://www.instructables.com/files/deriv/FG9/UBFO/FKB3DRCU/FG9UBFOFKB3DRCU.LARGE.jpg
RadioTrefoil says: Nov 27, 2012. 12:00 AM
The 1nF 4KV ceramic capacitors aren't being made anymore. Could they be replaced with 1nF 10KV caps?
somebody12345 says: Jan 16, 2012. 8:23 AM
how am i supposed to make this? the capacitors are obsilete
schumi23 says: Nov 3, 2012. 4:05 PM
What?
AChillyDog says: Jun 26, 2012. 6:52 AM
Sooo... endolith said this thing puts out 70 kv and Plasmana said this puts out 4 to 5 amps...If you could have this thing run continously for 1 SECOND,and have 30 ohms of resistance on a wire, it would produce 608 joules of heat, higher than the fusion heat of hydrogen.

Uselesss information, but i find it cool.
tesladude123 says: Aug 7, 2012. 12:29 AM
(removed by author or community request)
schumi23 says: Nov 3, 2012. 4:01 PM
1 amp hour. It means it can output 1 amp for one hour. But it can also output 2 amps for half an hour, or 4 for 15 minutes (Not exactly, it would be more like 4 for 10 minutes as as the amperage gets higher the] efficiency gets lower.)

jibatsu says: Sep 9, 2012. 9:33 AM
have thoroughly enjoyed making this. both the cockroft-walton and the marx generator were not just enjoyable to make but i also learnt a few things along the way, and for that i thank you!

I have two questions:
1) If you watch my video, you will notice arcing under the resistors to the left of the generator. I can't for the life of me work out why this is happening. any insight on the matter would be brilliant.

2) The spark gap and loud snap is perfect, but sadly the discharge time is a little slow for my liking. preferably without changing the design of the generator, is there any way you think of a way to speed it up?

My only idea was to increase the number of stages and output of the CW to hopefully charge up the marx quicker. I have no idea if that would be feasible, but for now my marx is running smoothly with roughly 9-10cm gap on a good day at about 5-6 second intervals.

zineb790 says: Jan 4, 2012. 5:04 PM
hi!
I wanna build this marx generator for my school project but the professor requires the input and output voltage and current (for safety issues) . pleaaaaaaaaaaase help ! :)
evilmadcow says: Sep 6, 2012. 2:38 PM
the output, as said on the inscrutable is easily 8,000 volts.
xenonic says: Sep 3, 2012. 8:26 AM
what would happen if i use 1kv capacitors instead of 4kv?
ipod135 says: Jul 2, 2012. 5:03 AM
would it be safe to use a 12 volt car battery for power instead of a double A (AA) battery?
p8ntball37 says: Aug 10, 2012. 4:18 PM
it wouldnt work. hes using an inverter do boost the voltage up to 450, and then a voltage multiplier to get around 7kv. hooking a 12v car battery directly to it wouldnt do squat.
THEfog says: Aug 9, 2012. 5:15 AM
Hey,

Signed up purely to ask this question. My Generator works fine in the sense that it successfully forms Oscillating Arcs. However, it fires very slowly - about once every 4 seconds. Now there is no Corona Effect happening and ive double checked the diagrams and ive built it exactly to spec - the only difference is I used 6Kv Capacitors instead of 4.

Any ideas would be awesome :D

Thanks!
AChillyDog says: Jun 2, 2012. 4:58 PM
Would a 12kv 30 mA power source work?
Dreistein says: May 1, 2012. 2:14 AM
hey i'd like to make a device i can attach to say my foot ,that if i touch someone they would get a shock basically like when you walk with socks over a carpet but the effect is automated. A guy made an ible http://www.instructables.com/id/The-mini-electrostatic-generator/ where he makes what im describing but its not very detailed. any ideas?
Aron313 says: Mar 9, 2012. 6:30 PM
Im gonna try to build one over the summer!
zineb790 says: Jan 4, 2012. 5:08 PM
hi!
I wanna build this marx generator for my school project but the professor requires the input and output voltage and current (for safety issues) . pleaaaaaaaaaaase help ! :)
BrunoG says: Mar 7, 2012. 1:19 PM
The scary step (step 2) First line:

The marx generators are dangerous high voltage generating machines, they produce a pulse discharge of many thousands of volts at approximately 5 to 10 amps! If the spark from the marx generator bites you, your life is over...
vamsi1 says: Feb 11, 2012. 4:34 AM
can any one give circuit details of 450v inveter used in above instrutable
vamsi1 says: Feb 11, 2012. 4:26 AM
Can any one give me circuit details and if possible circuit diagram for 450v inverter....
nathanielg says: Jul 1, 2011. 11:13 PM
(im actually fairly smart in electronics i just have no other way to really say this) i have shiny solder and when i melt it it is stilly shiny but when it cools it is dingy and looks like crap can anyone tell my why?
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