Cockcroft Walton Voltage Multiplier

Cockcroft Walton Voltage Multiplier

This started out as a quickie project, I had 15 x BY8410 10kv 2mA  diodes and a spare set of 8x 2n2 25kv capacitors. So I built a 3 stage CW multiplier stack. Quickly looking around for a PSU, I found a spare OBIT which gives about 25Kv P-P offload and I strapped the lot together.

The project worked very well indeed, It leaked electricity from every un-insulated point, but I got a decent voltage from the top.

This was fine untill I got too close with an earth and discharged the bottom capacitor through the bottom set of diodes (they selflessly gave themselves up to the cause).

So from this earlier success I wanted to use all of my 8 Capacitors and ordered a stack of diodes. This time I went for the BY8408's as they are rated at 8KV 5mA, but used a stack of four in each stage giving me a per stage over spec to 32Kv.

Each stage is insulated with silicon windscreen washer pipe, and the whole construction is (for now) taped to a peice of 1" trunking.

The output of the stack is protected with 10 x 1M 3Kv resistors (well they are flash tested to >9Kv each !!), and a set of 3 for each leg of the OBIT, to reduce charge up inrush.

Schematics...

Results.

Wow, this thing will charge me up to more than 70Kv from about 1' away (I know this as I was standing on a 3" length of pipe and could feel arcs to ground through my feet.!!). Flourecent lights light near it, It's like having an evil VDG, but with no moving parts..

Experement 1 Bouncing Ball

A polystyrine sphere, coated with aluminium foil, and suspended from a cord, as the power is applied the ball charged to the same potential as the sphere and thus is repelled. As the charge leaks away, the ball again touches the sphere, is charge etc...

Click Picture for movie. 633kb

Experement 2 Levitation

A polystyrine sphere, coated with aluminium foil is placed on the terminal, as the power is turned on the sphere is repelled, it floats off the ball.

Click Picture for movie. 289kb

Experement 3 Ion Spinner

A ion motor, made from a bent peice of copper wire, placed on a crude bearing. As power is applied the sharp ends of the spinner blow ion wind, pushing the spinner around.

Experement 4 Hair Raising

A wig is attached to the terminal, when power is applied the "hair" is all charged to the same potential, so each strand repells its neighbours.

(The stand is the top of an abandoned project a  rotary VDG .)

Click picture for the power on image..

Experement 5 HV Pie Cases

A pile of pie dishes is stood on top of the output terminal
As each pie dish gets charged, they fly off, one after another.

Click picture movie . 589K