Re: [TCML] Suitable MMC Capacitors

[DC Cox <resonance@xxxxxxxxxxxx>]

We carry MMCs in stock --- always have for the list members --- and sell
them for $3.25 each.  I get good pricing on them because I purchase them
1,000 pcs at a time.

I know it takes some brain-storming, but a kid I mentor started waxing cars
and he makes about $80 every two weeks doing this.  One has to be
resourceful as possible if working on a budget.

I agree with your comments on the mylar.  The mfg lists them only for DC
filter work in power supplies.  The 700 series they sell for pulse duty work
such as snubber apllications, etc.

Saltwater caps are fine for budget type coils, but the glass does absorb
approx 25% of the energy going into the cap as opposed to modern plastic
dielectrics which are very low loss..

Dr. Resonance




On Sun, Dec 6, 2009 at 11:55 PM, Paul Brodie <pbbrodie@xxxxxxxxxxxxx> wrote:

> D.C.,
> Please don't take this wrong. I'm not trying to be smart about this. I am
> asking you seriously.
> Which inexpensive MMC caps are you referring to that can be bought for the
> $40 from washing a couple of cars. Last I checked, the CD 942 caps run about
> $5.80 a piece when purchased in quantity. If Brandon were to build the
> recommended .008uF MMC tank cap, he would need 18 of them to get .0083uF at
> 36kV, which is approaching the 2.5 times the neon sign transformer voltage
> you recommend. So, to build this MMC, Brandon would need to come up with at
> least $104.40 for the caps alone. That is just for the caps and doesn't
> include bleed resistors or anything else required to build the MMC. If there
> are less expensive MMC type caps he can buy, will you please tell us what
> they are and where he can get them, if you know.
>
> I really like Jim Lux's recommendation to build salt water caps but it
> isn't my project. I'm just trying to help out. I did tell Brandon that I
> completely agree that Mylar caps are all wrong and not to use these caps. I
> was not aware that they are Mylar.
> Paul
> Think Positive
>
> ----- Original Message ----- From: "DC Cox" <resonance@xxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Sunday, December 06, 2009 4:52 PM
> Subject: Re: [TCML] Suitable MMC Capacitors
>
>
> The Fair Radio caps are DC filter caps.  If you buy them and then they
>> blow,
>> you are out your money plus more money to replace them.
>>
>> Use MMC type caps.  They are proven, will work, and won't fail like the DC
>> filter caps will.
>>
>> Just offer to wax a neighbor's car for $20.  Two cars and you have $40 and
>> you can buy the inexpensive MMC caps.  Car washing and waxing are just two
>> methods you can use to make some money to buy the caps you really need for
>> this project.
>>
>> Cutting corners on caps will just give you failure and it's not worth the
>> headache.
>>
>> Dr. Resonance
>>
>>
>>
>>
>> On Sun, Dec 6, 2009 at 11:47 AM, Paul Brodie <pbbrodie@xxxxxxxxxxxxx>
>> wrote:
>>
>> That is the correct list I was telling Brandon about but it is going to be
>>> of little help.
>>> Brandon, you are not building the type of MMC that is usually being built
>>> by other TC builders.
>>>
>>> For everyone to understand what is going on, I was attempting to help
>>> Brandon find some caps to use to build a tank cap as inexpensively as he
>>> can
>>> and still work with his 15kV 30mA neon sign transformer, as he is on a
>>> very
>>> tight budget. The caps we are looking at are only selling for 3 for $12.
>>> I
>>> located these caps at Fair Radio for him that are rated .01uF at 10kV. He
>>> wants to use 4 in series to get .0025 at 40kV and put together 3 strings
>>> of
>>> these to get .0075 at 40kV. I actually recommended 3 strings of 3 caps to
>>> get more capacitance, .01uF at the lesser voltage of 30kV, but he wants
>>> the
>>> extra voltage rather then the extra capacitance and says they will fit
>>> his
>>> budget. JavaTC recommends .008uF for his setup and I have always gone
>>> with a
>>> little bit more capacitance rather than less when given the choice. If he
>>> had the money, I would actually prefer he went with 4 strings of 4 caps
>>> to
>>> get .01uF at 40kV but I suppose that is immaterial.
>>>
>>> So has anyone got any advice for us, taking into consideration that the
>>> usual Cornell Debilier caps are out of the question due to cost. If you
>>> make
>>> a recommendation, please try to keep the cost under about $50 for the
>>> caps.
>>> That has been a very stiff requirement for me to meet, so far. Thanks
>>> everyone.
>>> Paul
>>> Think Positive
>>>
>>> ----- Original Message ----- From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
>>> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
>>> Sent: Saturday, December 05, 2009 4:03 PM
>>> Subject: Re: [TCML] Suitable MMC Capacitors
>>>
>>>
>>> This document is a bit old, but the only one I know of.
>>>
>>>> http://www.classictesla.com/hot-streamer/TeslaCoils/MMCInfo/good-bad.txt
>>>>
>>>> Take care,
>>>> Bart
>>>>
>>>> Brandon Hendershot wrote:
>>>>
>>>> I've heard rumors of a list in the archives consisting of caps known to
>>>>> work well in MMC's, and caps known NOT to be used in MMC's. I was
>>>>> unsuccessful in finding this list. If one of you could give a link to
>>>>> the
>>>>> post if you wouldn't mind. I'm trying to check up on these;
>>>>> https://www.fairradio.com/catalog.php?mode=viewitem&item=5330
>>>>> They're 'Dearborn 430P'. 3 for $12.00 isn't bad at all if they will
>>>>> work...
>>>>>
>>>>>
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>
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