Simple Low-Cost Inverter

The Simple Low-Cost Inverter circuit converts low-voltage DC power from a 12V 7Ah battery into alternating current (AC) suitable for powering low-wattage appliances like the included 230V 25W bulb. The core of the system relies on an analog switching topology utilizing 2N2222 NPN transistors and heavy-duty IRF250 MOSFETs outfitted with heatsinks to handle the high current demands safely. The transistors and resistors (650-ohm and 12k-ohm) form a switching oscillator network that drives the gates of the IRF250 MOSFETs, forcing them to rapidly switch the 12V battery current back and forth through the primary winding of the 12-0-12V 5A transformer (X2). This alternating magnetic flux induces a stepped-up high-voltage AC output at the secondary terminals of the transformer. Additionally, the circuit incorporates a 230V AC to 9V 500mA transformer (X1), a 1A bridge rectifier, a 1N4007 diode, and an LM7805 5V voltage regulator paired with smoothing capacitors (1000uF 50V, 100nF, and 2.2uF 50V) to manage control logic or auxiliary functions. A 5V single-changeover relay coordinates switching behavior, while the 2-pin connectors facilitate modular connections across the general-purpose PCB or breadboard.