ELECTRICAL CONDITION RESPONSIVE MONITORING APPARATUS-NAMELY, A SIGNAL GENERATING UNIT RESPONSIVE TO THE QUANTITY, OR PHYSICAL, ELECTRICAL OR CHEMICAL CHARACTERISTIC OR CONDITION OF COMPOSITIONS, MATERIALS OR OTHER PRODUCTS, AND A SIGNAL PROCESSING UNIT RESPONSIVE TO THE SIGNALS GENERATED BY SAID SIGNAL GENERATING UNIT AND CARRYING OUT COMPUTING, STORAGE, RECORDING AND/OR CONTROL FUNCTIONS DEPENDING ON SAID SIGNALS, SAID SIGNAL GENERATING AND PROCESSING UNITS BEING GENERALLY SOLD TOGETHER