Build a simple Marx Generator

Step 3 What you will need are...

I based the components I had easily available.
The recommended components you should get are ceramic capacitors and 1M 1 watt resistors. The ceramic capacitors are best suited for this project, because they are cheap, readily available, and they are good for in pulse discharge circuits. Polypropylene pulse-rated capacitor would also work well, but are more expensive, and harder to find with high voltage ratings. The resistors should be about 1M and 1 watt type, the normal 1/4 watt resistors are very unsuitable, if used, it will cause arcing and the resistors will burn out and damage the marx generator, so use the 1 watt metal glazed or carbon film resistors is suitable.

If in doubt, try building just a couple of stages first to see how well the parts you use will work before you buy more...

But I will tell you what I used...

• Ten 1nF, 4Kv ceramic capacitors
• Twenty 1M, 2 watt, 500v carbon film resistors (I brought the 2 watt resistors because they are somewhat cheaper then the 1 watt resistors!)
• Two 4.7M, 1 watt, 3.5Kv metal glazed resistor for the Rb.

Also you can use a base for your marx generator, the best suited base are glass (too fragile), ceramic (it's breakable) plastics (ideal, but some of them may be conductive), or whatever you think it is good! I use wood, a very baaad idea (because wood is conductive), but I have no choice, wooden base or no base.

You can use capacitors with larger values to get fatter, louder sparks, but take longer to recharge! You can often run capacitors in excess of their rated voltage, but obviously this increased the risk of failure!

And don't forget, the size of sparks at the output gap will depend on the input voltage and number of stages...

(UPDATE)
I got all my components from Farnell. Here is a list of things you will need to get if you are going to buy the components from Farnell.
1nF 4Kv ceramic capacitors
1M 2 watt 500v carbon film resistors
4.7M 1 watt 3.5Kv metal glazed resistor

Comments

[zineb790]

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]

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...

[somebody12345]

how am i supposed to make this? the capacitors are obsilete

[jaydenr]

Will it work to use 1nF, 6Kv ceramic capacitor? cant find 4kv

[p8ntball37]

it will take longer to charge up, but the spark will be much bigger!

[bwang]

Yes.

[bibbibbib]

anyone know of an american place that sells the components

[joehudy]

frys electronics ,and one online company elenco relly good and relly nice.

[bibbibbib]

thanks

[joehudy]

no problem you shold look in to allelectronics thay have relly good deals .does aneyone know a bout makeafair

[bibbibbib]

do you know where to get the capacitors? because none of them have the capacitors

[Mudbud]

Will a 0.003µF 4KV Film Capacitor work???

[Mudbud]

Well acutally, will these work?
http://cgi.ebay.com/50-x-0-33uF-100V-5-Mylar-Film-Capacitors-/320517601938?pt=LH_DefaultDomain_0&hash=item4aa0567a92

PLS REPLY!!

[Minimadnes]

can i use metalfilm resistors of the same specs

[tulavatalo]

are the Two 4.7M, 1 watt, 3.5Kv metal glazed resistor absolutely necesary

[Caspar]

If you can't get 3.5kV resistors, you could substitute 10 of the ordinary ones in series. (20 * .47 MegOhm)

[derbert]

i have some flash capaitors from cameras and i want to make something that'll spark like this, can i do that?

[brooklynlord]

Just adding some details.

Aluminium Electrolytic Capacitors usually do not have voltages above about 500 volts, which by using higher voltages may destroy the capacitors.

The capacitors shown here are ceramic capacitors, which can go up to a few kilovolts. The highest voltage capacitors i can find (Single) on digikey is about 6.3 kVs.

[Plasmana]

No, it will not work.

[dreadengineer]

Although, if you replace the spark gaps with SCRs, you can build a Marx generator using camera capacitors and the charging circuit from a disposable camera. Because each stage will be lower voltage (300V vice several kV), the sum will be lower voltage, so you won't be able to get a very long spark at all (rule of thumb is 30kV per cm of spark for blunt electrodes, though sharp points improve this some.) It's still good for some applications though. Here's a coilgun built using such a Marx generator:
http://lukeallen.org/coilgun.html

[brooklynlord]

If you can't get the wattage of the 1W 4.7M resistor, you can get a combination of other resistors in parralel :

9.31M ohms with
9.53M ohms------> Total resistance: 4 709 400 ohms (4.7094 M)

Another one:

12M ohms with
15M ohms with
16M ohms------->Total resistance: 4 705 900 ohms (4.7059 M)

[Plasmana]

Yes, you can do that if you want...

[brooklynlord]

How big is the energy gap on a 1-watt resistor? like, between the highest voltages and the maximum voltage? I would rather be safe than having a surge burn my resistors......

[JohnMichael]

If using different capacitors; how do I calculate what size resistors to use?

[Enterrupt]

In the cockcroft walton multiplier the caps determine your time constant and surge current.

Choose capacitors that can handle roughly 2x your max input. I used small ceramic disc caps. The smaller their value, the faster they will charge. This allows a more rapid spark. Larger caps will provide a bigger *bang* but there will be more time between arc discharges.

I tend to think smaller caps provide a better result for demonstrating HV here because the camera board does not source very much current at all.

[tulavatalo]

do you know a site that delivers thes components to other countries then uk

[7x13]

Try mouser.com

[firehand7]

Wood will change its conductivity as the humidity changes. An easy way to make wood a very good insulator is to coat it with Varethane or any other polyurethane or even several coats of varnish.

[cryptopsii]

@Derin Ha! I understand how always not know shipping cost must be annoying but i just went to farnell... THEY DO have a turkish page...

[utiruei]

your prints say that you need 6 capasitors and 10 resistores but later you say that you need 10 and 20 of this things

[Plasmana]

Well, I cannot add more than 6 capasitors and 10 resistors in the schematic.

[7x13]

for the Rb resistors could I use carbon film ones instead of metal, all the same specs.

[Plasmana]

If all of the specifications are the same, then yes, you can use the carbon film resistors.

[Mr. Apol]

Hello,

I am assembling the parts to build a Marx generator (you inspired me), but I have a couple of questions.

1. Can I use a Wimshurst machine as a power source? The output is DC, probably in the 20k to 30k range, with very low amperage.

2. Could I use a modified negative ion generator, such as offered here: http://www.goldmine-elec-products.com/prodinfo.asp?number=G1783

Thanks for the input.

[Plasmana]

The Wimshurst machine will take an heck for ever to charge the capacitors because of the high conra discharge rate. Using the ion generator is a much better idea.

[Mr. Apol]

Actually, I did try hooking up my Wimshurst machine to the Marx generator. It did work, after a fashion. As I cranked away, the spark gaps did fire--at slow intervals--but there was no discharge at the output end, just a steady blue brush discharge. Kind of interesting, but not exactly what was desired. Paul

[Plasmana]

Okay, I never thought a Wimshurst machine would charge up a marx generator, but it works for you... That is really interesting..

[Mr. Apol]

I have a couple of questions about using the ion generator. It has a single output--7.5 KV DC--so how do I hook it up to the Marx? Do I simply attached the negative output lead to one side of the Marx and connect the other Marx lead to ground? Paul

[Plasmana]

Yes, you got that right. The ion generators are really voltage multipliers packed in a case.

[Mr. Apol]

Success! The generator works beautifully with the ion generator. It fires about every 6-8 seconds, depending on the nearness of the grounded target. Here are two pictures of my Marx generator. I built it using a piece of perf board. You can't see the capacitor array, as they are underneath the perf board, In the picture it is insulated atop to china cups and grounded to the metal frame of my stove. Paul