Derek; You must understand, I have n formal education in this field, I am
just an old guy that thinks in PRACTICAL teams. I just figured that sparks
constituted LOSS, and I could be full of it where this is concerned!!
I can't tell you how many materials I tried before settling on this product.
The really great thing about using it with the wimshurst machine is that it
does not mark the discs and yes both neutralizers and collectors contact the
discs.
Look at my videos, that is all I use on any of my machines!
I would be happy to send some to you, I have more than I will ever use.
Doug
Sent: Wednesday, December 23, 2015 9:36 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] VDG pickups (was Ignition coil driver)
Doug,
Looking at the triboelectric scale for Polyethylene its near the
-ve end, so contact with neoprene you will get a charge build up,
although that should be counteracted by a similar charge build up at the
other end, so the net gain would/should be zero.
I agree about the spark losses. I always thought they were negligible,
but now I think of it they could be quite large, especially if the gap
from belt to collector is large. But the resistance of the sheet must be
quite large, so I would expect losses there too.
I can see how these would work for the neutralisers in a Wimshurst, but
not for the collectors in either machine, as they are to collect surface
charge, pushed out towards the collectors by the opposing charge on the
roller or other plate of the Wimshurst and not in full contact.
Do you use the film for both collectors and neutralisers in your
wimshurst? Are they both in full contact with the disks
Derek
On 23-Dec-15 1:38 PM, doug wrote:
Derek, I am sorry, I do not know the tribo property's of the plastic.
Here is my theory on why it works so well;
With the pickups sitting a little away from the belt you can see little
sparks passing, that is energy, like a spark gap. With the pickup point in
contact with the belt there is no charge dissipated from jumping the gap.
I could be wrong on this theory, all I know is that it works!
I use the same stuff on my Wimshurst machines in contact with the discs
with great success.
Here is the link to my source>>
http://www.all-spec.com/products/65-18.html
Doug
-----Original Message----- From: ExtremeElectronics.co.uk
Sent: Wednesday, December 23, 2015 2:51 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] VDG pickups (was Ignition coil driver)
Doug,
So the film is actually touching the belt?
If so, then you are adding another place for charge separation, as
well as collection. Any idea where on the tribo electric scale the
conductive film sits?
Would that account for the extra current ?
Derek
On 22-Dec-15 10:55 PM, doug wrote:
Hi Derek; What you see is conductive plastic film riding on the rollers
attached with copper tape, rollers are PVC and aluminum tape covered
acrylic. I did do comparisons, plastic film produced 30% more current.
Belt Is neoprene.
Doug
-----Original Message----- From: ExtremeElectronics.co.uk
Sent: Tuesday, December 22, 2015 4:52 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] VDG pickups (was Ignition coil driver)
Doug,
From what I can see from the videos, you are using a thin piece of
copper for your pickup. Have you done any comparison between that, wires
or gauze. Do you see an increase in current or voltage ?
What is the composition of your rollers and belt ?
Derek
On 22-Dec-15 2:34 PM, doug wrote:
Hello Derek;
Thank you for your comments and including a link to my youtube video. I
have included a link to my youtube page so you can take a look at some
of my VanDeGraaff projects. I think all VDG builders are using the wire
or screen type pickups on their VDG’s, I have found something MUCH
better. You can see it in operation in some of my videos.
Hello; I am looking for some information concerning Ignition coil HV
supplies. I am using 120V mains through a light dimmer and wonder if
there is something better and more robust than the dimmer? This
Ignition coil HV supply will be a dual coil setup using a
25.0uf/370VAC motor run Cap.
Not as cheap..
any of the standard capacitor discharge electronic ignitions basically
put 400V pulses into the coil to generate HV.
6000 RPM in a 8 cylinder engine is 200 Hz
typical energy per "pulse" is 100 mJ so 200 Hz is 20 W
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