Homemade Capacitor 19nF / 10KV

Here's a video on a homemade capacitor test and its failure at high voltage stress.

It was designed using plastic foil as dielectric, withstanding at 10KV maximum test performed.

It is using aprox 30cm x 40cm aluminium foil, and the corresponding plastic foil, cut into 3 longitudinal stripes, packed together into the black cylinder with red high voltage wires.

The test shows ~19nF capacitance, that varies with pressure applied to dielectric (air in between also changes with the pressure applied). The capacitor was covered in black tape to keep the pressure to a maximum level. Of course, it is not enough.

Charging the capacitor using the high voltage power source results in loud discharges once the spark gap is properly adjusted. The camera's framerate can't catch all of them, but the sound is recorded correctly.

At the end, the capacitor's dielectric is punctured, resulting in internal spark overs, and local heating around the middle. Basically this can be easily overcomed by using a better dielectric (ex: instead of 2 layers of plastic foil, use 3, etc).

A good alternative to highly expensive high voltage capacitors, easy to construct with aluminum foil, some good dielectric (I'd suggest plastic foil since it can be rolled), tape and a few wires. The capacitor is actually made by putting in parallel 3 internal capacitors:

---------- A
=======
---------- B
=======
---------- A
=======
---------- B
=======
---------- A
=======
---------- B
=======

3xA form a terminal, the 3xB form the other.

Power supply: http://www.pocketmagic.net/?p=1162

High voltage supply: http://www.pocketmagic.net/?p=802

Category:

Science & Technology

Tags:

• homemade
• high
• voltage
• capacitor

[ncranfill]

do by chance know of a way to make an nf 10v cap? specifically 440nf and 100nf. I need caps that are as close to nf while being around 10v.

[radumotisan]

@ncranfill yes, but better buy them, they are available everywhere

[kmncztms]

I made 2 leyden jars connected paralell to each other a few weeks ago. If I charge it with fur and plastic tube and approach the 2 wires, it makes a half cm long arc.

And I made your kind of capacitor today. If I charge it, it makes a very small spark.

Is it normal? :S

[radumotisan]

@kmncztms Yes, it is normal, because the leyden jars are suitable for electrostatic charging, while the capacitor in my video requires high voltage DC supply and won't work with electrostatic potential difference. The high voltage supply can be like the one I've used in a video (you can build one using a 555 circuit and a rectified flyback from TV/monitor)

[radumotisan]

@kmncztms the two caps you require cost no more than 30cents. Nevertheless it is possible to buld them using only paper and aluminum foil, but it depends on the application you plan to use them for, how well they would perform, so..the first question is what do you need them for?

[steadfast1984]

cool video, but it drives me crazy when people make vids and dont talk. like what are you doing when you squeeze it?

[radumotisan]

@steadfast1984 nothing, I just squeeze it :) . By doing so the space occupied by the dielectric becomes narrower and the capacitance increases .

[ncranfill]

@radumotisan I would if I have the money. unemployed and working on Teslian Tech...

[ipaqmaster]

1:10 WOW thats awesome XD

.. now touch it =P

[OrionXBlaze]

discharging so fast the camera can't keep up