As a starting device try 2 or more IRF 740 (400V @ 10A each) you have
better options if you don't put more than 200V on the FET you can use only 2
IRF 640 (200V  @ 18A each). MOSFets are really friendly devices when you pay
attention on how to handle then, especial care with driver circuits, some of
then  have quite a large input capacitive reatance. Cgs. There are especial
ICs (GATE DRIVERS) designed to deal with this problem if you don't want to
waste your time doing this.
    Hope it helps a bit.

P.S. the devices mentioned aren't expensive, I often buy then for  a buck or
less.

[ ] s
Horta


----- Original Message -----
From: Kevin Howell <kevin@RECORD.CO.ZA>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, April 13, 2002 3:26 PM
Subject: Re: [EE]:High power DC switching..


> I can't find any Mosfets that can handle 200-300V. The problem is not to
> source them but to find a suitable part. (Keep in mind the 20A)
>
> Thanks
> Kevin
>
>
> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Bob Blick
> Sent: 13 April 2002 06:44 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]:High power DC switching..
>
>
> > I have some high power fast switching transistors, BUV48, which I want
to
> > use to control a 220V DC motor using PWM. The transistor can handle 10A
Ic
> > and 400 Vce (hfe =8!!). My problem is that the motor draws up to 20A and
> > thus I will
> > need more than one of these transistors in possibly a darlington
> > configuration. Please can someone help me with a circuit to control this
> > current hungry motor using a pic ...
>
> Hi Kevin,
>
> Do you really have to use this transistor? Do you already have some
> other transistors to use as drivers for them? If not, perhaps you
> should consider some other transistors, I would suggest MOSFETs.
> Your losses will generally be lower. Also if you do PWM you will
> need a freewheel diode across the motor.
>
> Others will likely also have suggestions. A transistor with hfe of 8
> doesn't sound like a whole lot of fun.
>
> Cheers,
>
> Bob
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>
>
>

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics