Multiplying circuit for variable resistive load power measurement e.g. of plasma arc

摘要

The circuit incorporates a measurement capacitor (CMult) charged by the current (IVersorgung) drawn from the source of supply, and in parallel with the capacitor a semiconductor switch controlled by the supply voltage (UVersorgung). The capacitor is discharged to a voltage (UMult) which corresponds to the product of the supply voltage and current. It performs temporal smoothing of the result of the multiplication. The switch has a temperature-compensating resistance (RComp) between its emitter and the source of supply.