Electronic chip circuit, for detecting presence of any electrically conducting substance above or below given threshold, comprises logic circuit with chip inputs arriving via sensor contact

摘要

An electronic circuit detects the presence or absence of a substance having electrical conductivity, above or below a given threshold. The circuit comprises a logic chip (13). All chip inputs (14, 15) arrive via a sensor contact (17) as the same type of square wave voltage, resulting in a pre-determined output signal (16) to a display unit. A single alternating square wave current is continually generated and is taken as the reference for all functions and measurements. Alternating current is continually fed each sensor contact (17) via a capacitor (18). During measurements an active signal voltage is continually supplied at the chip (13) output (16) and activates a static liquid crystal display and/or an acoustic signal. The chip is a four-function NAND-IC, or two two-function NAND-ICs and a four-function Exclusive-OR-IC, registering five different conditions.