Hello my friends, i have this circuit and i'm asked to explain how Vin works here.
I know that FET's NORMALLY ON which means when 0V applied in its base it....works.
And when negative voltage is applied then it start to fall until Vgs(off). When V=Vgs(off) then it's OFF.
Ok i made a first explanation in my mind but it's not correct.
Well at first square-wave voltage source has 0V.
Ib(2n2222)=V/R=(-15)/2k= -7,5mA.
The voltage in the 2N2222 base is -15V so the 2N2222 doesnt "work".
So the only voltage we have in the IN4148 is the +15V from the Vcc source.
So the IN4148 works as cutoff, so no voltage in FET. so FET is normally ON.
When Square-wave source has 5V there's voltage in the 2N2927, so it is added in the -15V and the 2N2222 goes to working mode. and "sends" voltage in the 2N2222 collector and there's negative voltage in IN4148 cathode. If this negative voltage is below Vgs(cutoff)<-4V the FET goes OFF.
I know i say nonsense but i had to ask
I know that FET's NORMALLY ON which means when 0V applied in its base it....works.
And when negative voltage is applied then it start to fall until Vgs(off). When V=Vgs(off) then it's OFF.
Ok i made a first explanation in my mind but it's not correct.
Well at first square-wave voltage source has 0V.
Ib(2n2222)=V/R=(-15)/2k= -7,5mA.
The voltage in the 2N2222 base is -15V so the 2N2222 doesnt "work".
So the only voltage we have in the IN4148 is the +15V from the Vcc source.
So the IN4148 works as cutoff, so no voltage in FET. so FET is normally ON.
When Square-wave source has 5V there's voltage in the 2N2927, so it is added in the -15V and the 2N2222 goes to working mode. and "sends" voltage in the 2N2222 collector and there's negative voltage in IN4148 cathode. If this negative voltage is below Vgs(cutoff)<-4V the FET goes OFF.
I know i say nonsense but i had to ask