Bipolar CW

[abstruse1]

I've read several bipolar CW articles, but I'm having trouble getting two, half-rectified CWs working together.

1.  Is it necessary to use two separate flybacks?
2.  Two separate drivers?
3.  Will the bipolar design work with full wave CWs, or do they need to be half wave?

Finally, could anyone give me a simple schematic of the two multipliers hooked up together?

Thanx, guys.

[abstruse1]

We seemed to have figured this out.  With two, 7-stage half rectified CWs, oppositely polarized, I'm getting 18" of strong, loud sparks.  I had to shut down to move the setup to a larger cart and spread out, since there was a lot of unintended sparking between the various wires.  Based on the last run at 18", this setup is capable of at least a few more inches.

Stay tuned!

[Mads Barnkob]

Hi Abstruse, I am loosing overview of which projects you are talking about, is all your CW threads about the same project?

Could you please list the threads in a reply, then I can merge them all together, so it makes more sense. There is no need to make new threads for every single question, its better to keep it one long thread, else all history is hard to find.

[abstruse1]

Mads, I have several CW projects (efforts, really) that have gone from almost nonfunctioning to quite satisfactory.  My soft goal is to generate 36" hard sparks (not arcs), so I'm hoping to get ~18" from a single CW, then duplicate it except for polarity, and let them arc to each other.

We dug out an early, half rectified, 7 stage CW and duplicated it except for polarity.  They work fine together,getting (so far) 18" sparks.  I'm using an inductive heater driver and a 1,000 turn home made flyback that has been reliable, both of these powering the dual CWs.

At this point, my main question is can I do the same polarity trick with two fully rectified CWs.

Stay tuned.

[Coupling]

If I understand what you are asking, then yes, you can do a bipolar arrangement of full-wave CW multipliers. I have worked with so-called "center-fed" full-wave CWs personally.

[abstruse1]

Got it.  Thanx, guys.

[Vdekje]

I find Falstad-ing things like this to be a helpful sanity check: https://tinyurl.com/23w7rxts

Left is a bipolar center-tapped full wave, right is a bipolar halfwave. The disadvantage of a center-tapped full wave is that it requires double the supply voltage. You can also use a center-tap grounded transformer in the halfwave bipolar CW (I think... the high inductance between the multiplier and ground could be an issue (e.g. secondary flashover) during low-impedance sparking), so you really do need a supply with double the voltage capability. On the other hand, you'll notice that under a 4MΩ load the output voltage of the center-tapped full wave is around 2.75 times that of the halfwave.

I believe using higher voltages per stage is advantageous in regards to voltage sag (even accounting for the accompanying reduction in capacitance) due to the reduced stage count, so the higher required supply voltage would become a larger issue if you push stage voltages higher. Another bonus of lower stage counts is that the first capacitor only sees pk supply voltage, not 2x pk supply voltage, so you need fewer capacitors total.