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Re: [TCML] Looking for pulse cap
Shannon -
Sorry, but in my opinion presenting a manufacturer with a totally fraudulent
"manufacturing plan" to try and "trick" him into providing free samples is
completely unethical. It may even be illegal.
All "sample" parts provided by manufacturers cost money to fabricate, test
and ship. Manufacturers provide samples to Engineers and product developers
to stimulate usage of the parts in real-world products, which results in
volume sales of that component and profit for the company. By lying to a
manufacturer about your bogus "product requirements" and potential future
sales, and obtaining samples based on those fraudulent claims, you are
negatively affecting that manufacturer's bottom line.
American manufacturers are slowly being squeezed out of business by many
factors. Don't add to their problems by cheating. Unfortunately, most
component manufacturers don't really have the resources to check the
legitimacy of sample requests.
If you REALLY have an interesting or unique application for a manufacturer's
components, talk to someone in the company's Marketing department, and let
them know that while your project is simply an amateur experiment, it may be
an interesting new application for their product, that you would like them
to consider helping to support your project, and that you will send them a
report and photos of the completed widget. If they agree, great. If not,
then just save your pennies and buy parts like the rest of us.
If you can't affort to purchase the parts for your Tesla projects, take up a
different hobby.
Regards,
Herr Zapp
----- Original Message -----
From: "Weinhold Shannon L" <Shannon.L.Weinhold@xxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, September 16, 2009 10:04 AM
Subject: RE: [TCML] Looking for pulse cap
You could always try to obtain samples from Cornell Dubilier...
They are pretty motivated to provide them if you present them with a
well written usage plan indicating that you intend to incorporate them
into something that you are manufacturing and intend to purchase a lot
more in the future.
I'm not going to say how many they sent me, but they are plenty generous
to potential customers.
"Failures are divided into two classes
those who thought and never did,
and those who did and never thought."
John Charles Salak
-----Original Message-----
From: Dave Leddon [mailto:dave@xxxxxxxxxx]
Sent: Tuesday, September 15, 2009 1:25 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Looking for pulse cap
Phillip, Steve,
Thanks for your insight. You both responded almost simultaneously with
the suggestion that I raise the value of my tank cap to 1 uf which has
several advantages, not the least of which is that it reduces the
capacitor count down to something almost manageable. Using the
940C8W2K-F caps ($5.99 at rell.com) I could get by with 9 strings of 17
each and given that I already have 38 of these on hand my out of pocket
expense would only be, ka-ching $690. Still a bit more than I can
justify. So if anybody knows where I can score 1 uf at around 10,000
volts for less money, please let me know.
Thanks,
Dave
Pleasanton, ca
At 11:20 AM 9/15/2009, you wrote:
Herr Zapp,
The lower voltage ratings you may have seen were for 2 reasons: less
current and secondly, they were over stressed.
I used to run my MMC caps with peak AC voltages at the DC rating, and
after enough time, one by one, the caps would fail. Testing shows that
the cap makers arent fibbing about the VAC ratings, stick with that and
it will last for a really long time.
Dave,
Id suggest going up higher than .5uF, perhaps to 1uF or so (i didnt
specify this in our correspondence). Im running 1.25uF on an
experimental setup at 1500A, but a lower frequency. While you get less
amp-turns in the primary, you do arrive at the higher peak current
level faster, which translates to achieving a certain top voltage on
the toroid faster, which is more efficient (in my data i saw a 20%
efficiency improvement going from 8 cycles to 5 cycles of operation by
increasing the tank cap value). You have current to spare with those
big CM600s, so you should have no problem producing well over 10 foot
sparks (id guess in the 14-16 foot range, secondary coil withstanding).
Steve
On Tue, Sep 15, 2009 at 10:48 AM, Quarkster <quarkster@xxxxxxx> wrote:
> Matt -
>
> Eh??
>
> Clearly, my post contained no answers whatsoever, only questions to
> try to gain a better understanding of Dave's rather unique capacitor
requirements.
>
> Most of the large DRSSTCs that I've seen get by using a cap with a
> lower voltage rating, but they may not actually be attaining a
> primary current of 2400A.
>
> Regards,
> Herr Zapp
> ----- Original Message ----- From: <mddeming@xxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Monday, September 14, 2009 5:37 PM
>
> Subject: Re: [TCML] Looking for pulse cap
>
>
>
>> Hi Herr Zapp,
>>
>>
>>
>> Interesting questions, but how do they relate to answering the
>> question Dave asked?
>>
>> Matt D.
>>
>>
>>
>> -----Original Message-----
>> From: Quarkster <quarkster@xxxxxxx>
>> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
>> Sent: Mon, Sep 14, 2009 4:36 pm
>> Subject: Re: [TCML] Looking for pulse cap
>>
>>
>>
>> Dave -?
>> ?
>> A few questions:?
>> ?
>> 1. How are you calculating the voltage requirements for the tank
cap??
>> ?
>> 2. How large a multiplier are you using to define the capacitor's
>> voltage margin (safety factor)??
>> ?
>> 3. What is the manufacturer's voltage rating for the IGBTs you will
>> be using??
>> ?
>> 4. What is the calculated peak primary current??
>> ?
>> Regards,?
>> Herr Zapp?
>>
>>
>>
>>
>> ----- Original Message ----- From: "Dave Leddon" <dave@xxxxxxxxxx>?
>> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>?
>> Sent: Monday, September 14, 2009 11:19 AM?
>> Subject: [TCML] Looking for pulse cap?
>> ?
>> Hi all,?
>> ?
>> ? I'm working on a fairly large DRSSTC and I find that an MMC
>> adequate to
>>
>> ?the task may be out of my financial reach. If I were to push the
>> igbt
>>
>> ?bridge to its limits I would require a cap rated at 20 kv at 0.5
mfd.
>>
>> ?This begins to sound like pole pig territory. If anyone has a cap
>> like
>>
>> ?this that they would consider selling, or if they know of a
>> resource that
>>
>> ?I can pursue, please let me know.?
>> ?
>> Thanks,?
>> Dave?
>> Pleasanton, Ca?
>> ?
>>
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>
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>
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