Hi, Neil.
Beside changing the R2 position, you can use a series zener diode connected 
to R1 and I/O pin. I think that a 9V1 would do the trick.
Cheers,
Fabricio.



----- Original Message ----- 
From: "PicDude" <picdude2@avn-tech.com>
To: <piclist@mit.edu>
Sent: Wednesday, June 11, 2008 1:53 PM
Subject: [PIC] +12V high-side transistor switch?


>
> I need to switch on/off a 12V load, high-side, from a PIC running on 5V, 
> and
> tried this circuit, but the output is always on.  With the PIC I/O 
> floating
> (set as input), the load should be switched off, and with the I/O low, the
> load should be switched on.  I'm using 1k for R1 and 10K for R2.  The load
> will be up to ~250mA, btw.
>
> Any idea what I'm doing wrong here?  The circuit...
> http://www.narwani.net/neil/electronics/PIC-HS12VSwitch-01.gif
>
> -- 
> View this message in context: 
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