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In this work, a protective circuit for a direct current (DC) to alternating current (AC) converter system commonly referred to as an inverter have been designed and implemented. The method employed a simple operational amplifier (Op-Amp) circuit wired as a comparator to serve as input into the microcontroller, a NOT AND logic gate also known as NAND gate connected in a shutdown circuit mode to serve as output of the microcontroller, a microcontroller which functions as an interface circuit between the comparator and the shutdown circuitry and a visual display that relays what is happening within the controller to the outside world. Equipment such as automatic voltage regulators, automatic inverter systems and so on make use of Op-Amp to provide safety for the components that make up the device. This paper focuses mainly on the use of Op-Amp in ensuring the longevity of electronic systems; it does this by providing: no-load, low-battery and overload sensing signal to the input ports of the microcontroller. The 80C51 microcontroller which was simulated using Proteus/Mide software package have been used to generate the appropriate output signals required to operate the NAND logic gate wired as a shutdown circuit. With the aid of an external shutdown circuit arrangement, the entire system can be shut down after given a prior warning alarm about all the conditions earlier mentioned above.
Keywords: Op-Amp, Microcontroller, Inverter, Ports, Battery.