Hi Dears.
i want to measure the current of power mosfet without using an current transformer. Do you know any transistor based circuit which can measure the mosfet current.
Thanks.

 

Basically, insert a low value series resistor. Measure the voltage across this resistor. Use ohm's law. Amplify this voltage using a transistor circuit.

Choose a resistor that gives about 0.5V drop at the maximum expected current. Calculate the power dissipated in the resistor at full current. Use a resistor that can handle this power.

The problem with this arrangement is that there is no isolation between MOSFET circuit and the measuring circuit.

Hall-effect current transformers are getting cheaper. Google.

 

Basically, insert a low value series resistor. Measure the voltage across this resistor. Use ohm's law. Amplify this voltage using a transistor circuit.

Choose a resistor that gives about 0.5V drop at the maximum expected current. Calculate the power dissipated in the resistor at full current. Use a resistor that can handle this power.

The problem with this arrangement is that there is no isolation between MOSFET circuit and the measuring circuit.

Hall-effect current transformers are getting cheaper. Google.

thanks but i mean to say transistor based circuit. like a current mirror circuit.