Instructables

Step 3: What you will need are...

Picture of 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

 
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sarvesh73 months ago

can we use electrolytic caps??

twotower1 year ago
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!

Rb = Ballasting Resistor

jeanrenaud4 months ago

Hi, i've made a 5 stage Marx Generator, with initial voltage ±10 kV (hard to tell i can't measure it reliably, but it's a CRT monitor flyback).

After some experiments, all the resistors between stages blew out (my ohmmeter shows "OL"). In your instructable, you used 1M 500V 2W carbon resistors. I've choosen 1.8M 1W 3.5 kV metal film resistors. I'm not sure how this happened ;)

My ballast resistors (rated 10kV) are still ok.

Any idea, guys ? I don't blame anybody but myself ;) but some opinions are welcome.

is their anyway i can salvage capacitors from various motherboards; and would it make a difference that they were all different.
ipod1352 years ago
would it be safe to use a 12 volt car battery for power instead of a double A (AA) battery?
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.
how am i supposed to make this? the capacitors are obsilete
zineb7902 years ago
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 ! :)
jaydenr3 years ago
Will it work to use 1nF, 6Kv ceramic capacitor? cant find 4kv
it will take longer to charge up, but the spark will be much bigger!
bibbibbib3 years ago
anyone know of an american place that sells the components
Mudbud3 years ago
Will a 0.003µF 4KV Film Capacitor work???
Minimadnes3 years ago
can i use metalfilm resistors of the same specs
tulavatalo4 years ago
are the Two 4.7M, 1 watt, 3.5Kv metal glazed resistor absolutely necesary
derbert4 years ago
i have some flash capaitors from cameras and i want to make something that'll spark like this, can i do that?

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.

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)

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......
JohnMichael5 years ago
If using different capacitors; how do I calculate what size resistors to use?
tulavatalo5 years ago
do you know a site that delivers thes components to other countries then uk
7x13 tulavatalo5 years ago
Try mouser.com
firehand75 years ago
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.
cryptopsii5 years ago
@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...
utiruei5 years ago
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 (author)  utiruei5 years ago
Well, I cannot add more than 6 capasitors and 10 resistors in the schematic.
7x135 years ago
for the Rb resistors could I use carbon film ones instead of metal, all the same specs.
Plasmana (author)  7x135 years ago
If all of the specifications are the same, then yes, you can use the carbon film resistors.
Mr. Apol5 years ago
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 (author)  Mr. Apol5 years ago
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.
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
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 (author)  Mr. Apol5 years ago
Yes, you got that right. The ion generators are really voltage multipliers packed in a case.
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
PICT0072.JPGPICT0073.JPG
Plasmana (author)  Mr. Apol5 years ago
Great job! I am glad that you did! If you want, to make it fire faster you can to put a little blob of hot glue on every connection, this will decrease the corona discharge therefor it will charge up the capacitors faster and it is very likely to fire faster.
I used some silicone caulk. We'll see how much effect that has. Now I wonder if I can adapt my homemade leyden jars into another one . . . Paul
An update: silicone bathroom caulk proved effective. I lowered the sparking interval to 4 seconds. That seems to be about the best it can do. Insulating the connections also helped the Wimshurst machine charge the generator. Instead of a slow fizzle and spark gaps triggering every 12 seconds, I now get genuine discharges from the Marx about every 8 seconds. I have to crank pretty briskly, but it does work. I am wondering, if I build another Marx generator using my soda can leyden jars as the capacitors, will I need to use higher rated resistors. I don't know the exact capacitance of my leyden jars. Most formulae for calculating it rely on measurements of the conducting surface, etc. and i don't know how to figure the surface area of a soda can . . . regards, Paul
Plasmana (author)  Mr. Apol5 years ago
Okay, I never thought a Wimshurst machine would charge up a marx generator, but it works for you... That is really interesting..
skuitarman5 years ago
could I use 3kv 5pf capacitors instead
Plasmana (author)  skuitarman5 years ago
yes.
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