I have written extensive notes on the theoretical aspects of power supplies, voltage regulators, current sources, and inverter designs using Arduino and 555 timers, as these circuits are fundamental to electronics. Recently, I shifted my focus toward practical implementations, starting with basic power supply circuits like mobile charger adapters, CFL bulb drivers, and DC-DC converters. However, frequent power outages in my area have disrupted my WISP internet links due to unstable power delivery to my networking equipment—MikroTik routers, Ubiquiti devices, and a TP-Link router. This prompted me to explore DIY UPS solutions on a tight budget.
Initially,
I considered repurposing a spare car inverter(SAA-1000A, 1000W, 12VDC
to 230VAC modified sine wave) with an Arduino-based automatic transfer switch. This car inverter is shown below.
However, research revealed that modified sine wave inverters can damage sensitive electronics like MikroTik routers, making this approach unsuitable. An alternative solution involved bypassing the inverter entirely and using buck/boost converters to power the equipment directly from a battery, with an Arduino and voltage sensor managing the UPS switching. Unfortunately, this also posed challenges: my primary router, the CCR2004-16G-2S+, lacks a DC input, requiring risky internal modifications to tap into its 24V rail—something I’m unwilling to attempt on a new device.
While I may experiment with these DIY methods for other projects, I’ve decided against testing them on my critical WISP equipment due to the risks of damage or fire. Instead, I’ll invest in a commercial UPS with a battery backup, ensuring a reliable, long-term solution for maintaining uninterrupted power and service quality. Safety and stability take precedence over cost-cutting for this setup.
