Current control circuit for inductive load - uses amplifier with voltage feedback to link load current to amplifier input voltage

摘要

This circuit, controlling the current flowing through an inductive coil, uses an operational amplifier with negative voltage feedback. The control input signal (1) is connected to the non-inverting input of an operational amplifier (2). The amplifier output is connected to one end of the coil (3). The other end of the coil is connected to the 0 volt d.c. rail (6) via a resistor (5), and is also fed back (7) to the inverting input of the amplifier (2). If the impedance of the coil is considerably greater than the 'R' of the feedback resistor (5), the current 'I' through the coil is related to the input voltage 'U' by the Ohm's law expression: U/R=I regardless of inductive phase-shifts.