RE: [TCML] charging reactors

["Jim Mora" <wavetuner@xxxxxxxxx>]

What about a beefy HV transformer secondary say a small pig or PT?
Jim Mora

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of bartb
Sent: Monday, March 02, 2009 6:58 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] charging reactors

Good points Ed.

You know, I've been a crappy guitar player since I was 5. With that 
experience, I couldn't help but look at Hammond Manufacturing when Jim 
mentioned the "charging inductor" (many good tube amps use Hammond RF 
Transformers). Hammond does build a 5H 500mA choke which would suffice 
for this application if it were not for the high voltage. Voltage is a 
big problem here with the charging inductor. In order to create the 
voltage winding standoff, the insulation thickness becomes a burden on 
winding a 5H inductor. Even the 5H 500mA choke Hammond produces (193P) 
is about the size of a hefty MOT, and it's rated at only 800V. It's not 
an easy assignment as stated earlier. Digikey offers the 193P at $170. I 
can't imagine what a 10 to 20kV version would run if there were such a 
beast.

Regards,
Bart



Ed Phillips wrote:
> I hate to be negative but you're talking about really serious chokes 
> here and nothing you can do with "several hundred turns on a U core".  
> You want a lot of inductance with a lot of DC flowing through the coil 
> and that's something you're not going to get by casual 
> experimentation.  I would guess you'd need a high-quality transformer 
> iron core with cross section of at least 4 square inches, a fairly 
> large air gap, and lots of wire with special attention to insulation.  
> You can probably find power inductor design information on the web if 
> you hunt around.  If you can find something meeting your 
> qualifications for $50 that would be a super bargain!  I'm looking at 
> a 1958 Stancor catalog and see that a 6 henry, 500 ma choke has a base 
> size of 5-5/8" x 5-1/2" and is 8-1/8" high.  Shipping weight is 24 
> pounds and list price 50 years ago was $54.00.  A 10 henry, 1 amp 
> choke from UTC is 4-3/4" x 6-7/8" x 10-1/2" and weighs 40 pounds.  Net 
> price was $40 half a century ago!  Neither of these transformers is 
> designed for high pulse voltage across the windings and that would of 
> necessity require more insulation with more iron and more copper.
>
> Good luck,
> Ed
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