Re: [TCML] MOT ballasting options

[ADAM MUNICH <ajm9414@xxxxxxx>]

Before you attempt anything with CW multipliers, I urge you to read this
first; http://adammunich.com/cw-multipliers/

CW's aren't very good circuits, and for the frequency an MOT runs at you're
going to need huge (expensive) high voltage caps in order to get anything
useful out of the network.

-Adam



On Fri, Jan 4, 2013 at 10:48 AM, Carl Noggle <cn@xxxxx> wrote:

> Good caps for ballasting are motor run caps.  If you can't get them used,
> Grainger sells a lot of them.  You could use motor start caps, but they
> would need to be derated in current since they aren't meant for continuous
> service.
>
> ---Carl
>
>
>
>
>
> -----Original Message----- From: Atomic
> Sent: Friday, January 04, 2013 4:57 AM
>
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] MOT ballasting options
>
> Take a look at Greg's
> coils<http://www.**capturedlightning.org/hot-**streamer/greg/frames.htm<http://www.capturedlightning.org/hot-streamer/greg/frames.htm>
> >,
> this one <http://www.capturedlightning.**org/hot-streamer/greg/Mark_**
> III.htm <http://www.capturedlightning.org/hot-streamer/greg/Mark_III.htm>
> >uses
> 4 MOT caps and a lot of small diodes as both voltage doubler and
> ballast. I believe you can add 2 more caps to ballast further if you want.
> I don't think a single gap will work well because the current is too high
> and it won't stop flowing easily and actually single gaps work better with
> higher voltages.
>
> On Fri, Jan 4, 2013 at 12:22 AM, Brian Hall <brianh4242@xxxxxxxxxxx>
> wrote:
>
>
>> Thanks all for the advice and experience stories, even the CW rectified
>> schematic to get DC HV from the output of a MOT.
>> Are there any circuit diagrams or basic description for how I would use
>> microwave oven caps (and possibly diodes) to have a capacitive ballast,
>> since it sounds like it may have the least amount of power loss?  While
>> still keeping the current draw to 10 amps or so?  It also sounds easier
>> and
>> less expensive than making an inductive ballast since I have most of the
>> good innards of four or five microwaves.   I want to probably start
>> simple,
>> maybe a 12 to 18 inch high secondary with a 1:4 ratio on its cylindrical
>> dimensions, driven from a single MOT.   Could I get by with a single
>> static
>> spark gap where its only 1 to 2 kv? Or would it even help to get a higher
>> HV out using the MOT, MOC and diode straight from the microwave to get a
>> higher voltage, if the diode can handle the power from the bigger HV out
>> and not just from the little cloth covered wire for the magnetron?  Has
>> anyone popped a microwave diode before from putting it straight on the 1
>> to
>> 2 kv output of the MOT?
>>
>>
>>
>> ------------------------------**----
>>
>> Brian Hall
>>
>>
>>
>>
>> > From: cn@xxxxx
>> > To: tesla@xxxxxxxxxx
>> > Subject: Re: [TCML] MOT ballasting options
>> > Date: Thu, 3 Jan 2013 13:20:38 -0700
>> >
>> > Hi, David,
>> >
>> > Your incandescent resistor warming your garage proves that every cloud
>> has a
>> > silver lining.  Kind of like the old vacuum tube oscilloscopes.  A
>> couple of
>> > Tek 517s would keep a garage pretty warm, too.  What do you use for an
>> > inductive ballast?
>> >
>> > Cheers---
>> > Carl
>> >
>> >
>> >
>> >
>> >
>> > -----Original Message-----
>> > From: drieben
>> > Sent: Thursday, January 03, 2013 5:51 AM
>> > To: Tesla Coil Mailing List
>> > Subject: Re: [TCML] MOT ballasting options
>> >
>> > Hi Carl,
>> >
>> > Yes, you do bring up a good point as to the power waste of
>> > resistance ballasting in large coils. I have a large power resistor in
>> the
>> > control panel of my Green Monster coil that I can add in series to my
>> > everpresent inductive ballast, if I so choose to help in smoothing
>> > the output or just for additional attentuation. I believe the mea-
>> > sured resistance of my power resistor is only 0.5 ohms, so you'd
>> > think thaere wouldn't really be that much in the way of voltage
>> > drop here. However, when you're typically running ~60 amps
>> > that translates to 1/8 of the total circuit impedance at 240 volts
>> > input (240/60 = 4 ohms), so that's 30 volts dropped out. I have
>> > the option of  switching the resistive ballast on or off while the
>> > coil is in operation and the difference in the output sparks is
>> > definitely noticable! The sparks become noticable dimmer and
>> > weaker looking when I add the resistance. Also, the resistor
>> > will gradually warm to incandesence if ran in this manor, as
>> > 30 volts x 60 amps = 1800 watts of wasted power! On the
>> > bright side, the resistive heating does contribute to warming
>> > my garage on these cold winter days ;^)
>> >
>> > David
>> >
>> > ----- Original Message -----
>> > From: "Carl Noggle" <cn@xxxxx>
>> > To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
>> > Sent: Wednesday, January 02, 2013 10:19 PM
>> > Subject: Re: [TCML] MOT ballasting options
>> >
>> >
>> > > It would be good to stick to capacitors or inductors for ballasting,
>> since
>> > > they don't dissipate any power (ideally).  A resistor such as light
>> bulbs
>> > > or salt water will reduce the power available from the source.  It
>> would
>> > > only be practical for small coils.  The most efficient resistive
>> ballast
>> > > would dissipate half the power in the resistor and half in the TC.
>>  Using
>> > > a DC supply and controlling the firing rate is probably the best ide,
>> > > needing no ballast.  Have to watch out for the large energy storage in
>> the
>> > > C-W capacitors, though.
>> > >
>> > > BTW, the rectifier circuit in the drawing is a center-fed
>> Cockroft-Walton.
>> > >
>> > > ---Carl
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > -----Original Message-----
>> > > From: Jim Lux
>> > > Sent: Wednesday, January 02, 2013 8:53 PM
>> > > To: tesla@xxxxxxxxxx
>> > > Subject: Re: [TCML] MOT ballasting options
>> > >
>> > > On 1/2/13 6:58 PM, Andy Cobaugh wrote:
>> > >> On 2013-01-02 at 17:17, Jim Lux ( jimlux@xxxxxxxxxxxxx ) said:
>> > >>>
>> > >>> the "500 ft spool of wire" as an inductor has some simplicity and
>> > >>> appeal.. I can't recall what it's inductance is, but it's on the
>> list.
>> > >>> (copper being expensive these days, it's not as cheap as other >
>> >>> means)
>> > >>
>> > >> I think the 500ft spools of #12 THHN stranded copper measure around
>> 9mH.
>> > >> The mostly complete spool that I use with my potential transformers
>> > >> measures 8.5mH.
>> > >>
>> > >
>> > > 9mH = 3.4 ohms at 60 Hz, 2.8 @ 50
>> > >
>> > > 1 spool = 35 Amps at 120 V, 60 Hz
>> > >
>> > >
>> > >
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