Siemens Polyphos 30, X-RAY Collimator and Image Plate Teardown (Part 2 of 3)

Teardown of the Siemens Polyphos 30 collimator and image plate. Collimator had an interesting moving blinds design with a lot of gears, pulleys and strings. …

Siemens Polyphos 30, X-RAY 125kV head teardown (part 1 of 3)

Teardown of the Siemens Polyphos 30 X-ray head which contains step-up transformers, voltage multipliers and a rotating plate x-ray tube and a lot of oil! …

AC vs DC fuses, high current, explosive destructive testing and theory

Littlefuse 300A 32VDC fuse destructive test Protistor 200A 690VAC fuse (naked) destructive test: Protistor 200A 690VAC fuse (housed) destructive test: High Voltage Fuse Teardown video: …

Merry Christmas & Happy New Year 2018 (X-ray teardown edition)

Pictures as promised: Teaser for the upcoming teardown videos of the Siemens Polyphos 30 x-ray machine, complete with control panel, inverter, collimator, detector/grid plate …

GE AMX-II, mobile 110kV X-RAY system teardown

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5kJ capacitor bank fired at 2kJ charge

Second charge experiment with the bank of 35 electrolytic capacitors connected in series. The bank did however not get charged to more than 50% of …

5kJ capacitor bank, 1.5kJ BANG test at end!

For now all details during development and testing can be found on the forum thread: 35 capacitors in series, each 450VDC/1000uF, for a 48 …

A new dedicated high voltage forum!

Hello everyone! The comment sections on my website have grown long with questions, advices and solutions. So I have expanded the site with a brand …


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24 kV Marx generator


This was my first high voltage circuit that eventually led me into building other high voltage generators, supplies and Tesla coils.

A Marx generator works by the principle of charging up a number of capacitors in parallel and when the voltage is high enough to break down the spark gaps, the capacitors will be discharged in series. When a Marx generator fires, it is said to be erected.



WARNING!: Working with electricity is dangerous, all information found on my site is for educational purpose and I accept no responsibility for others actions using the information found on this site.

Read this document about safety!


A Marx generator can work as a electromagnetic pulse generator, at high energy levels, if it is not shielded and grounded correctly. You can risk damaging electronic equipment if this circuit is not constructed or operated in a safe manner with these precautions in mind.

In the construction of the Marx generator it is very important to give great thought to distances that works as insulation between stages and components. An advantage against spark gap jitter can be achieved easily and for free by designing all the spark gap in one line where they can see each other. The UV light from the first spark gap will help break down the following spark gap and so forth.

The ideal Marx generator circuit will deliver n times the input voltage with n stages. So with a 4 kV supply and 6 stages, ideally I should have 24 kV output.

Each stage of 1 nF is charged to 4 kV and gives me 0.008 Joule energy per stage. With all 6 stages in series the capacitance is now 1/6 and the voltage is 6 times higher. So the erected capacitance is now 167 pF with 24 kV across it resulting in 0.048 Joule discharge energy.



Voltage supply 4 kV at 20 mA / 20 kHz from a solid state neon sign transformer.
Stage design 6 stages of 2x 1M5 3500 V charging resistors and 1 nF 7500V capacitors
Discharge 24 kV at 0.048 Joule
Longest arc 20 mm sparks




14th April 2008

The 4 kV supply used is a solid state neon sign transformer that delivers 20 mA. The output comes at 20 kHz from the switching and normally is no problem for a neon tube, but I need to rectify it to use it in the Marx generator as DC supply is needed. A string of 10 1N4007 diodes are used for a 10 kV rectifying diode.

3500V 1M5 metal-oxide resistors were used with two in series for each stage and 1 nF 7500V ceramic capacitors, this gave a good head room for a 4 kV stage voltage.

The long leads on the capacitors were used as the spark gap by soldering them to the string of resistors as far up the legs as possible and then bending them into forming spark gaps.



A Marx generator in this size and level of supply voltage is a very forgiving and hard to break circuit. This makes it perfect as a entry level circuit for high voltage experiments.

The few number of components makes it cheap and it is easy to source the high voltage capacitors on Ebay.

The sparks generated from the Marx generator is very loud and it is easy to gain higher voltages and thus longer sparks by just adding more stages. A circuit that is easy to upscale just by adding more stages and where output is quickly calculated with number of stages.

Definitely a must-build circuit for everyone with a interest in high voltage generation and experimentation.



28th April 2008