Bias: favorite BJT/JFET bias guide

Collector-feedback bias 

@8/14 2012

Gate is grounding. focus on R4 selecting.

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MPF102

            Vgs(off) = -8V

            typical Idss= 2mA to 20mA ( i guess most of in range 2mA to 5mA, sometime, you need checking this)

             R4=680R

                              Vgs= -Vs= 1V      Id=1.5mA   @Idss=2mA

                              Vgs= -Vs= 1.9V  Id=2.9mA    @Idss=5mA

                              Vgs= -Vs= 2.5V  Id=8mA       @Idss=8mA

             R4=1.6k

                              Vgs= -Vs= 1.9V  Id=1.2mA    @Idss=2mA

                              Vgs= -Vs= 3.1V  Id=1.9mA    @Idss=5mA

                              Vgs= -Vs= 3.7V Id=2.3mA     @Idss=8mA

             R4 = 2.7k

                              Vgs= -Vs= 2.5V  Id=1mA       @Idss=2mA

                              Vgs=-Vs=3.8V    Id=1.4mA    @Idss=5mA

                              Vgs=-Vs=4.4V    Id=1.6mA    @Idss=8mA

             R4=3.3k

                              Vgs= -Vs= 2.8V  Id=0.8mA     @Idss=2mA

                              Vgs= -Vs= 4.0V  Id=1.2mA     @Idss=5mA

                              Vgs= -Vs= 4.6V  Id=1.4mA     @Idss=8mA