RE: [TCML] DC coils

["S&JY" <youngs@xxxxxxxxx>]

Jon,

 

6 MOTS in series.  Center two grounded and in ammo box with transformer oil.
Actually the cores are connected to an analog milliamp meter and then to
ground so I can monitor the DC current without the meter being at a high
potential.  There are back to back diodes across the meter for safety in
case the meter opens up.  Each pair of outer transformers is also in their
own separate ammo box with oil, with the cores insulated from the boxes.  

 

Bridge rectifier, each leg having 28 1N5408 rectifiers in series.  Filter
cap was sized for not more than 8% ripple at 250 ma.  It is 0.67 mF at 18
KV.  It is made up of six series connected banks of 4 paralleled 1 mF 3KVDC
microwave oven caps.  Each bank has a bleeder resistor across it made up of
15 220K ¼ watt resistors.  

 

I also monitor DC voltage with a surplus analog DC milliamp meter.  Since
the center of the power supply is grounded, I use two sets of 40 1 meg ¼
watt resistors in series as voltage dividers, one to the plus side and
another one to the minus side so the KV meter stays at ground potential.  I
have two other meters to monitor AC voltage and current to the MOT
primaries, which run off of variac controlled 240 VAC.  Voltage to each MOT
is kept below about 100 volts to keep them from saturating.

 

The goal was to minimize expense.  The oven caps and meters were purchased
surplus, and I made my own meter scales and shunts.  The MOTs were
cannibalized from junked ovens.

 

S. Young

 

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From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Jon Danniken
Sent: Friday, January 28, 2011 4:21 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] DC coils

 

S&JY wrote:
>
> A twin TC produces connecting 6 ft streamers at 150 bps
> with an input power of 1164 DC watts (9.7 KV at 120 mA) which was
> 1548 VA out of the wall plug. (My power supply is only roughly 75%
> efficient since it uses 6 MOTs.  A pole transformer would be better.)

Thanks for posting your specs on that, Steve, your success is very
encouraging to me.

One thing I am curious about is your MOT HVDC supply configuration.  How are
your MOTs configured, and what did you use for the rectifier and cap?

Thanks,

Jon

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