Re: question about driving a DC sync spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Matt Whitman" <teslacoiler@xxxxxxxxxxx>

Hi, I use a DC motor on my async rotary spark gap. It is a 110v 10,000RPM
1/2Hp motor. I am just driving it using a variac and a bridge rectifier (not
sure the rating but probably somewhere around 25A 400v) with 200v 470uF
filter cap. Power levels on my coil are somewhere between 8-10KVA and on
average I get 8' arcs.  http://72.228.95.56/whitek/8inch.htm   I do my best
to keep arcs away from my power feed lines. I don't run my coil that much,
but I haven't had any problems with the rectifier.

Matt Whitman
teslacoiler@xxxxxxxxxxx
www.electronsgonewild.com
KC2IEV



----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, October 11, 2006 11:08 PM
Subject: question about driving a DC sync spark gap


> Original poster: "miles waldron" <mileswaldron@xxxxxxxxxxx>
>
> Dear All,
>
> Is anyone using a DC motor to drive an async rotary spark gap? If anyone
is
> doing this, how is your variable DC power supply built? We are having
> consistent CATESTROPHIC failure of the power supply diodes. Not the motor.
> The motor is always fine, and the variac is always fine. We are using huge
> giant diodes (300V @400A) and they are frying instantly. We have tried
> chokes in series, caps in parallel, caps in series, but nothing seems to
> help.
>
> Please help before we shoot the DC motor with a 1000 watt CO2 laser, and
> rebuild our spark gap using a variable AC motor.
>
> Background:. This is an 11" OD coil 57" tall #18 wire, 15kva pig, 11 to 15
> foot arcs.
>
>
>