Chopper circuit using a current controlled switch

The circuit below is a chopper circuit using a current controlled switch (X1) to limit the amount of current flowing in the coil. The switch X1 is configured to sense current from resistor R3. Once the current is over 460ma the virtual switch in X1 is turned on and pulls to low the drive to the main coil switching transistor X5. When the current falls below 400ma, X5 will energize the coil and the process repeats. Note that the large difference between the on and off current sensing has been used for illustrative purposes only.

Chopper Circuit (Download circuit A/D 2000 | A/D v4)

Note: No attempt has been made to model the motors magnetic characteristics in this simuation.

The same circuit using a transistor and diode can be found by clicking HERE.