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Re: [TCML] Looking for pulse cap

Matt -

Actually, profit margins for "commodity" component manufacturers are very, very small. If you were to compare the profit margins for every link in the component distribution chain, you will almost always find that the MANUFACTURER has the lowest profit margins, frequently operating at only a few percentage points of gross revenue. If you are offering a sole-source proprietary component, margins can be quite a bit better, but for commodity resistors, capacitors, etc. margins are universally low.

When a domestic manufacturer approaches a zero-profit margin situation with a particular product, he has several options:
1. Discontinue the product;
2. Move the production of the product to a location where manufacturing costs are (temporarily) lower (Mexico, China, etc). 3. Reduce material costs by using lower-quality materials, and possibly reducing product performance margins (product still "meets" specs, but is not as robust).

In the case of C-D capacitors, as Tesla coil builders we certainly don't want options #1 or #3 to occur.

As Americans, we shouldn't want option #2 to occur.

I may be in the minority, but the approach of "lying to get free stuff" is just fraudulent and doesn't seem be the right way to conduct your business.

(A slightly different scenario, but I had the same gut response when immediately after the Gulf hurricane disasters, some list members were gleefully gloating about all the "free" pole pigs that they could simply pick up and haul off, not giving a damn about who might suffer in the long run.)

It's just not ethical.

(End of rant.)

Herr Zapp
----- Original Message ----- From: <Mddeming@xxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, September 16, 2009 11:20 PM
Subject: Re: [TCML] Looking for pulse cap

Even hundreds of samples constitute a miniscule part of  their advertising
budget. Hundreds of thousands are spent each year to get their name out in front of potential buyers. Even if they weren't, when I think of affecting
the bottom line of a multimillion-dollar corporation by a  dollar or so I
can only say:

Matt D.

In a message dated 9/16/2009 10:25:21 P.M. Eastern Daylight Time,
quarkster@xxxxxxx writes:

Shannon -

Sorry, but in my opinion presenting a manufacturer with a  totally
"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
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
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
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
different hobby.

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.

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.


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).


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
> 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
>> ?
>> 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
>> ?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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