The liquid level within a storage tank network is continuously monitored by a transducer system of the present invention formed essentially of MSI's (Medium Scale Integrated Chips) including a differential pressure (dp) cell in circuit with a digital volt meter (DVM) which, in turn, is
A "red-alert" end condition digital signal is generated by a transponder system of the present invention formed essentially of MSI's (Medium Scale Integrated Chips) including an oscillator/ripple counter controlling a fixed Gray code logic encoding network in circuit with a programmed