Hi Guys,

I have a problem with my control circuit for Mosfets. The source of the Mosfet that I will be using will be connected to -10V while the drain will be connected to a resistor then the resistor will be connected to ground. I need to connect 15V to the gate of the mosfet and I want it to have a switch so that I can connect and disconnect the 15V from the mosfet turning the mosfet on and off. I have a control signal for the switch that has 0V(low level) and 12V(high level) level. This control signal will control the circuit by disconnecting the 15V from the gate of the mosfet. I need help on designing the circuit. I can only use Mosfets, resistors and BJT for the control circuit.

See attached file for the illustration of the circuit.

 

Hint - the FET is off when the gate-source voltage is 0. It is full on when the G-S voltage is 10 volts.

 

Your battery, V3-10+, should be connected to R2 instead of the ground symbol. Then the source of the FET is connected to ground.

 

The mosfet circuit is already existing, the only circuit that can be change is the control circuit and I am having problem designing a control circuit since the source of the mosfet is connected to -10V and the control signal starts from 0V. I need to have a control circuit that will turn off the mosfet when the control signal is 0V and turn on when the control signal is 12V.

 

Also, be aware that most mosfets have a Vgs rating of only 20V. So, you will be exceeding that with -10 for source and 12 for gate.

John

 

Here is a quick schem. to get the wheels turning,

Think in terms of electronic switching.

It won't work as an actual circuit, just use this for a idea to get you started in a direction of some sort.