Thanks Tony and David - putting the relay on the drain side of the HEXFET
worked.
Love this list!
David

                -----Original Message-----
                From:   Tony Nixon [mailto:Tony.Nixon@ENG.MONASH.EDU.AU]
                Sent:   Wednesday, December 08, 1999 8:46 PM
                To:     PICLIST@MITVMA.MIT.EDU
                Subject:        Re: Logic Level HEXFET's

                "Fansler, David" wrote:
                >
                > I am working on a project that uses a PIC to operate 3
logic level HEXFET's
                > (IRLIZ44N & IRLD014) that is driving me crazy.  I was
under the impression
                > that logic level HEXFET's would (when +5V is applied to
the gate) would open
                > up an pass whatever voltage was on the drain to the source
(within the
                > limits of the device).  Ain't happening.  All I get is 6 -
7 v through the
                > device, with 24vdc on the drain.  And yes, I do have the
gate, drain, source
                > pins correctly identified.  I have tried high side, low
side and would try
                > third side if I knew how.
                >
                > Basic circuit is
                >                 +24vdc
                >               |
                >                 Drain
                >  +5V------Gate
                >                 Source
                >               |
                >            24 vdc relay coil
                >               |
                >              GND
                >
                > To date I have not even put the PIC in the circuit, but
rather just fed 5v
                > from the power supply.
                > Any ideas or help would be greatly appreciated - I am
beginning to doubt my
                > manhood!
                > Thanks
                > David

                Perhaps put the relay on the drain side, with a protection
diode.

                --
                Best regards

                Tony

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