At 04:03 PM 2/27/02 +0000, Graham North wrote: >Hi all, > >I need to control (turn off) a depletion mode mosfet with a Pic output >(the Pic is running from a 3.3V supply). Is this possible? As far as I >am aware a depletion mode mosfet conducts with a zero volt potential on >the gate, and is turned off when a negative potential is applied to the >gate. Is there an easy way to do this with a Pic output? Yes - and no! First - use a P-channel FET - something like a J174 thru J177. A positive gate voltage (with respect to source) turns the FET off. I use LOTS of this family! Your main problem is the low supply voltage. The closest part from the J17x family would be the J177 - the maximum rated pinch-off voltage is 2.5V. The problem is the channel resistance is quite high at 300 Ohms. VGS VGS ON RESISTANCE PART MIN MAX MAX 174 5 10 85 175 3 6 125 176 1 4 250 177 0.8 2.5 300 The above data from the Fairchild web site. Hope this helps! dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.