Continuous measurement of slowly chopped DC signals over a high dynamic range

Slowly decreasing DC signals, being chopped at a frequency of only 0.3 Hz, were measured over a dynamic range of at least 50000. Using a special sample and hold circuit together with a narrow bandwidth lock-in amplifier allowed a continuous measurement over the whole range without changing the amplifier sensitivity. Thus any interruption of the measurement caused by the long amplifier relaxation time constant after switching over the sensitivity could be avoided.