n channel mosfet switch

[govardhanamma]

hi,
i want use irf 630 n-channel mosfet by grounding the drain voltage and by applyin -5v to the source resistor,and by gradualliy increasing the gate voltage from 0v to saturation of mosfet ,will this circuit will work ,my aim is to achieve -5v across resistor during off condition of mosfet ,.......will it work

 

[dselec]

hi,
i want use irf 630 n-channel mosfet by grounding the drain voltage and by applyin -5v to the source resistor,and by gradualliy increasing the gate voltage from 0v to saturation of mosfet ,will this circuit will work ,my aim is to achieve -5v across resistor during off condition of mosfet ,.......will it work

Ok why do u want to complicate matters by grounding drain ?
it will need u to apply positive isolated vgate in ref. to source, or to apply higher voltage than min 5v to start with.
why dont u post the circuit u trying to make and ill help.
dselec

 

[govardhanamma]

we have connected the circuit as given in the image but we have connected drain to the ground and source to supply i,e -5v, trough a resistor of 1.5k,and if VGS is 0 it is showing -3.3v across resistor after raising the gate voltage the voltage at the source is decreasing,but my doubt is with out conducting the how it is showing -3.3v at source terminal...................actually i want -5v at source terminal in off stage of MOSFET please suggest any corrections in my circuit

 

[alexan_e]

Connect the load to the drain and not the source side.
If you connect the load in the source side then as the current increases it will create a voltage drop across the resistor and this will increase (more positive) the voltage of the source.

Exactly as the circuit above but replace gnd with -5 and +5 with gnd

Alex

 

[dselec]

T gov..
"my aim is to achieve -5v across resistor during off condition of mosfet"
no way if u using mosfet in series of resistor.
if have resistor in paralel u will get -5v on resistor and then short the mosfet and get zero ... you will need additional resistor in series or fet, or u can use 2 transistors and connect +/_ voltage.
unless u tell us more about what u want to do ...sorry we are all wasting time here.