TIMBER CORROSION DECISION DEVICE

PURPOSE:To measure the ratios of the corrosion of timber quantitatively by detecting the attenuation ratio of frequency components having impact sounds and the containing ratios of two different frequency components. CONSTITUTION:The impact sounds produced when a wooden column is striken with a hammer or the like are applied via a microphone 1, low- and high band pass filters 2, 3 to a detecting circuit 4, which converts the same to fluctuation signals of DC components. On the other hand, after the lapse of prescribed different times from the trigger signal of the impact sounds, the outputs of the circuit 4 are held in sample holding circuits 5-7. The value of the circuit 5 is divided by the values of the circuits 6, 7 by a divider 8, and the results thereof are held in sample holding circuits 9, 10, and further the values of the circuits 9, 10 are applied together with the constant from an amplifier circuit 11 to an adder 14 via amplifier circuits 12, 13. The degree of corrosion is displayed in a meter 15. Thereby, the corrosion is easily decided simply by giving impact by a hammer.