Design and Construction of a Digital Voltage Duration Counter

Timing a process is a critical aspect of modern engineering and daily life. Power — a fundamental resource in both developed and developing nations — demands precise duration measurement for industrial, domestic, and billing purposes. This is especially relevant in regions experiencing power supply instability. This paper presents the design and construction of a digital voltage duration counter that records, displays, and stores the duration of a connected A.C. load. The system incorporates a voltmeter for simultaneous voltage measurement and employs the PIC16F84 microcontroller — a mid-range, 8-bit RISC device — as its central processing element. A seven-segment LED display unit renders real-time count output, with a dual-display configuration providing redundancy. The device includes three push-button controls: a Wake/Sleep switch, a Reset switch, and a Dual-Change switch. The maximum measurable duration is determined by the number of display units employed; this implementation used five seven-segment displays, yielding a ceiling of 10,000 seconds. Testing confirmed that the circuit met all design objectives accurately and reliably.