Inrush-Current-Control Circuit

The electronic circuit shown in the figure regulates the inrush current that arises upon initial application of voltage to capacitors. This inrush-current-control circuit is intended principally to be incorporated into an electronic instrument in which capacitors are used to filter out current spikes and noise that would otherwise be impressed on the instrument power-supply bus. In the absence of a circuit like this one, voltage would be applied to the capacitors abruptly - typically by closing a relay; the resulting high inrush current could disrupt the power-supply bus and thereby also adversely affect the operations of other instruments connected to the same bus.