Re: question about driving a DC sync spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "James" <mustang3@xxxxxxx>

    Be sure your spacing (from motor to any portion of the spark gap 
is sufficient). I would shoot for an inch and a half of clearance. If 
the SG arcs to the motor, it's curtains for the rectifier. I use a 
250V25A bridge with no problems. Chokes, caps, etc. are not required. James

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, October 11, 2006 10:08 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.