Agree on the benefit of active charge spray.
I've built a largish unit (almost 2m high, 40cm dia topload) with a 6KV DC PSU I get off ebay spraying charge onto a Kapton belt. Works a treat giving up to about 1m sparks in good conditions. I've also got some high value resistors insider the terminal which give enough voltage drop to drive a second downward spray. It does almost double to current output.
-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Teslalabor
Sent: 24 December 2015 09:57
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Subject: Re: [TCML] VDG pickups (was Ignition coil driver)
Hello,
it seems that only self-exited van de graaf generators are built by you folks. Why not use an external DC source (10-20kV) and spray the charge on the belt, like all big generators do the job? Wouldn't that be much easier to realize than dealing with triboelectric scale and humidity problems?
Regards,
Stefan
----- Original Message -----
From: "ExtremeElectronics.co.uk" <tesla@xxxxxxxxxxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, December 23, 2015 3:36 PM
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.
>>>> https://www.youtube.com/user/dr043042#p/u
>>>> https://www.youtube.com/watch?v=YCWAH-J091c
>>>> https://www.youtube.com/watch?v=uoS7sOy2Src
>>>>
>>>> Thank you again, Doug J.
>>>>
>>>> -----Original Message----- From: ExtremeElectronics.co.uk
>>>> Sent: Friday, December 18, 2015 11:35 AM
>>>> To: Tesla Coil Mailing List
>>>> Subject: Re: [TCML] Ignition coil driver
>>>>
>>>> You can get about 300W from 8 of them though..
>>>>
>>>> http://www.extremeelectronics.co.uk/electronic/v8-tesla-engine/
>>>>
>>>> Derek
>>>>
>>>>
>>>>
>>>> On 18-Dec-15 2:30 PM, Jim Lux wrote:
>>>>> On 12/18/15 4:39 AM, doug wrote:
>>>>>> 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
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Tesla mailing list
>>>>> Tesla@xxxxxxxxxx
>>>>> http://www.pupman.com/mailman/listinfo/tesla
>>>>
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>>>
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