Re: Solid-State Marx (fwd)

["High Voltage list" <hvlist@xxxxxxxxxx>]

Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 15 Jul 2005 10:44:50 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>, hvlist <hvlist@xxxxxxxxxxxxxxxxx>
Subject: Re: Solid-State Marx (fwd)

At 07:55 AM 7/15/2005, High Voltage list wrote:
>Original poster: <sroys@xxxxxxxxxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Fri, 15 Jul 2005 13:17:13 +0930
>From: Matthew Smith <matt@xxxxxxxxxx>
>To: High Voltage list <hvlist@xxxxxxxxxx>
>Subject: Solid-State Marx
>
>Hi All
>
>This idea started off as something driven by the flash unit from a
>disposable camera until I realised that I'd forgotten about driving the
>MOSFET gates!
>
>Here's the schematic:
><http://www.mss.cx/img/ssmarx1_sch.png>  (image 917x348px, 5.8kbytes)
>
>I have a rail of spare MOSFETs that can be used in this design:
>PHP6N60E; Vdss=600V, Id=5.4A, Rds[on] < 1.8 Ohms
>
>Capacitors are photoflash types from disposable cameras.
>
>Assume that the input voltage to the circuit is about 250V.
>
>What would be the best way to achieve switching of the charging
>transistors?  Put gate windings on the step-up transformer for
>synchronous rectification (lose the diode)?
>
>(I'm going to worry about the discharge part once I've got the charging
>sorted.)

If you're doing a fairly high rep rate, how about capacitively 
coupling?  Or, stack transformers.

The challenge on a Marx is getting all the discharge switches to turn on 
together.

You might want to look at the Fitch configuration, which is less sensitive 
to the simulanteity of the switching.


>Cheers
>
>M
>
>--
>Matthew Smith
>South Australia
>http://www.kbc.net.au