This paper presents the design, development, and field validation of a compact, energy-efficient high-voltage electric pulse energizer specifically engineered for elephant deterrent fencing in Sri Lanka’s rural and wildlife-conflict regions. The system is developed as a low-cost, serviceable alternative to imported energizers, which are often expensive, difficult to repair, and not optimized for local environmental or infrastructural conditions. Built around a self-oscillating fly-back converter topology powered by a 12V DC source, the energizer generates intermittent high-voltage pulses up to 10 kV, suitable for protecting extended fence lengths. A discrete power transistor drives the oscillation and transfers energy to a capacitor bank, which is discharged via a silicon-controlled rectifier (SCR) to deliver sharp and consistent pulses. A ferrite-core transformer with an auxiliary feedback winding ensures self-regulation, reducing control complexity and improving circuit robustness. The system is compatible with solar power systems and adheres to the Sri Lankan Standard SLS 1765:2023, making it appropriate for off-grid rural deployment. Field implementation at the Weerawila Open Prison demonstrated successful energization of a 4 km perimeter using two units, with 24-h continuous operation over 90 days. The system showed excellent uptime, durability, and effective deterrence. Its modular, discrete-component architecture supports local manufacturing and repair, positioning it as a sustainable, scalable solution for human-elephant conflict mitigation across similar regions in Asia and Africa.