Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!zaphod.mps.ohio-state.edu!wuarchive!uunet!abvax!iccgcc!gibbonsj
From: gibbonsj@iccgcc.decnet.ab.com
Newsgroups: sci.electronics
Subject: Re: Transistor Selection
Message-ID: <4632.2837e6fb@iccgcc.decnet.ab.com>
Date: 20 May 91 20:10:51 GMT
References: <1991May14.003221.5725@unhd.unh.edu>
Distribution: usa
Lines: 23

In article <1991May14.003221.5725@unhd.unh.edu>, jwm712@unhd.unh.edu (Jonathan W Miner) writes:
>   I need to switch a 12 volt / 1 Amp circuit using a 5 volt CMOS
>   control.  What type of NPN transistor do I need?  I have

> Thanks in advance.
> Jon.

Don't use a bipolar transistor, use a MOSFET.  International Rectifier (IR) 
makes an IRF*** series that will do the job real nicely, and the gate drive just
looks like a 1000 pF cap (not too hard to drive with regular logic!).

If the load is inductive, be sure to damp the ringing with an RC snubber.
For example, the IRF531 has an Rds(on) resistance of 0.18 Ohms, and can handle 
60 volts Drain to source.   

Hope this helps!

-- 
  John Gibbons             N8OBJ                     Macedonia, Ohio

           "Welcome My Son, Welcome To The Machine" - Pink Floyd

           Of all the things I've lost, I miss my mind the most...