Re: Neon Power Supplies
Subject: Re: Neon Power Supplies
From: richard.quick-at-slug-dot-org (Richard Quick)
Date: Mon, 18 Dec 1995 23:11:00 GMT
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Quoting napier-at-cats.ucsc.edu (Mark Napier):
>Forth, use a heavy ferrite toroid RF choke in series with the
>line to the tank circuit. I am becomming convinced listening to
>comments and conversations out here that the RF chokes are being
>ignored. It seems that it is difficult to make these chokes have
>too much inductance, and the tendency is to make them too light.
>For the novices out there who are learning the ins and outs of
>tuning, coupling, toroid loading etc., these chokes are really
>going to add life to your neon power supply if you wind enough
>inductance into them and use them. Richard Quick
> Richard, I have the full protection circuit you describe. I got
> the specs from your video. I have been setting the safety gap
> to where it fires every few seconds or so. It is about 1/4"
> right now. Is there a maximum gap beyond which the neons will
> not be safe?
Yes, but if you are doing things right (and it sounds as if you
are) you should not have to open the safety gap up. In a well
tuned and coupled coil system the energy oscillates through the
tank circuit (L1-C1-G1, where L1 is the primary, C1 is the pulse
discharge capacitor, G1 is the main system spark gap) and should
not be kicking back into the supply lines. Therefore it is
possible to open the main system gap, G1, up wider that the
safety gap and still have little or no activity at safety gap.
A quarter inch between each HV line and ground on the safety gap
is pretty narrow. Once you can verify that the coil is in pretty
good tune, and the safety gap is just flicking gently every few
seconds or so (meaning that is you are seeing no loud cracks and
really bright flashes indicating kickbacks), you can open the
safety gap up up to 3/8-1/2 inch between each electrode and
ground, where is does not fire at all.
> Also after a few minutes of firing, the chokes are pretty
> warm. Nothing else in the protection circuit is. Just the
> choke coils. The wires running to them are cool. They are 14
> turns of #12 stranded on 2" x 1" ferrite cores. Is this a
I am not positive what the problem is. But I have had ferrite
toroid choke cores heat up when they were placed too close to the
tank circuit and they were laying orientated on the same plain as
the primary coil. I physically position the toroid core 90
degrees off-axis from the primary windings. This prevents the
choke core from being coupled into the primary coil field flux.
What I mean here is that if the primary coil is orientated like a
pancake, or a saucer sitting on a table, the ferrite core should
be orientated like a hoop that a dog could jump through. This
avoids the possibility of the ferrite toroid acting like a
I also place my HV filter board as far away from the tank circuit
as is reasonable. On small coils this means a minium of about
five feet, on larger coils it is more like 15-20 feet.
> I'm getting up to 40" arcs right now. (4 x 24", #22 wire).
> I want to get that larger toroid on there and see what
> happens. I can't wait to get my new commercial caps on this
I bet! This project sounds really hot!
... If all else fails... Throw another megavolt across it!
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