Elektorskop, Teil 4 (Oszilloskop)

The dual-slope technique is one of the simplest and most reliable DVM systems. The voltage to be measured is fed to an integrator for a fixed period of time . The current into the integrator, and therefore the charge on the integrator capacitor at the end of this period, is proportional to the input voltage. The capacitor is then discharged at a (known) constant current and the time taken for the capacitor to completely discharge is measured. Since the discharge curren t is constant the time taken to discharge is proportional to the original charge, which in turn is proportional to the input voltage.