Let's Make Robots!

Marx Generator (HIGH VOLTAGE !!!)

Produces very high voltages

So here is a little toy I recently made. I was inspired by Plasmana on www.instructables.com. I followed/modified his instructions to make a Marx Generator power by a Cockroft-Walton voltage multiplier. This baby should be putting out around 40-50kV. I don't have the equipment needed to verify that but I know its putting out at least 30kV (based on the length of the air gap between terminals. The list of supplies bellow is based on what I used to make it. It is not the best way to make it but these are parts I had/was able to source easily.

** The time I get excited in the video about a spark there isn't one, it was a corona discharge that made a "pop" sound. You do get to see a discharge at the begging and right before I turn it off though.

Supplies:  

34 1N4007 diodes
34 100nF film 275V capacitors
10 1nF 4kV capacitors
100mA fast blow fuse
18 1M 1W resistors
20 470k 1W resistors
25 1.1K 1W resistors
Lexan Plastic

Functionality:

This setup works by using a Cockroft-Walton Voltage multiplier that outputs an about 6000V DC to the Marx generator. The Marx Generator then charges up in parallel and discharges in a series. This discharging cascade results in very high voltages of about 40-50kV (in theory) and probably about 30kV in practice.(Images bellow from Wikipedia) 


CW Voltage Multiplier


Marx Generator

Pictures of Build/Sparks;



CW Generator Finished

Building the Marx Generator


Discharge!


Capacitors Discharging in Series via Spark Gaps

Whole System 

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Enjoyed your walkthrough - simple electronics with a lot of history and impact (in many ways)......

A question :- each capacitor stage multiplies the voltage by how much approx ?

A second question :- how long does each charge cycle take - (before its ready to spark) ?

The 1st stage CW generators (gray) each hold the RMS value of 120 AV main. That means each of those gives me about 170V [120xsqrt(2)]. So 34 of those give me 5770V DC.

The 2nd stage Marx Generator capacitors each hold can hold up to that 5770V and then discharge in series to give up to 57 700V. However, my caps are rated for 5000V each. As such I made the spark gaps smaller so no capacitor charges past 5000V. With my setup a 1mm gap can be jumped by a voltage of about 1100V. My gaps are 3-4mm meaning each capacitor charges to 3-4kV. (The caps momentarily experience voltages higher than the 5000V they are rated for when the whole system discharges but it's so fast/current so low they are able to handle it.)

The charge cycle depends on your capacitor values and needs to be calculated using difficult math for RC circuits. I didn't bother doing the theory on that because this was a project just for fun. My setup takes about 30sec. to charge from 0 to full.

Thanks for the compliments and interest :)

Mini-artificial lightening! Nice work Gonzik

If only. Lightning has a voltages in the millions of volts or so....several orders of magnitude greater than my little generator =(

Hence the word mini (I've previously researched lightening so I hear ya on a big difference).  At least it will jump an inch though

Yeah, thanks for the compliment anyhow though =)

Awesome!