#### slow_rider

##### New Member

I'm building a negative ion generator for a friend. I'm using a full wave Cockroft-Walton voltage multiplier (http://upload.wikimedia.org/wikipedia/en/thumb/4/47/Full_wave_Cockcroft_Walton_Voltage_multiplier.png/180px-Full_wave_Cockcroft_Walton_Voltage_multiplier.png with the diodes reversed since I want negative voltage output). I've built 10 stages on an a thick plastic panel. At this point I have two questions:

1. Because of the number of capacitors in the circuit the inrish current will be big, how can I limit it (and how to calculate)?

2. I want to keep the Vout high but limit the current in case someone will touch one of the needles of the ion generator. I have a bunch of 1MOhm 5W rated resistors, I'm thinking to limit the output to 1mA but for that I need to fill a hole in this formula:

Eout = 2n * Epk - Vdrop

n = Stages

Epk = AC input peak volatge

==>

Eout = 2*10 * 311 - Vdrop

Eout = 6220 - Vdrop

Vdrop = [ Iload / (6*f*c) ] * (n^3 +2n)

Iload = Load in Amps

f = freq. Hz

c = Capacitance in Farad

n = stages

(after calculations) ==>

Vdrop = (Iload / 0.000003) * 1020

So the big question is - what is my load? If I'll know that I can calculate the resistor value according to ohm's law.

Any help will be really appreciated!

Thanks