12V To 220V Modified Sine Wave Inverter

DIY 300W Modified Sine Wave Inverter (12V to 220V)By Creative For You

In this project, we are building a high-performance 300W Modified Sine Wave Inverter. This device is designed to convert 12V DC (from a battery) into 220V AC, allowing you to power household appliances like LED bulbs, fans, and chargers during power outages or for off-grid applications. Using the SG3525 PWM IC, this prototype offers a stable frequency and high efficiency compared to simpler transistor-based designs.Supplies

Electronics Components: * PWM Controller: 1x TL494 IC 1× IR2110 * MOSFETs: 2x IRF3205 (High-current switching) * Transformer: 12V-0-12V to 220V (Ferrite core or Iron core) * Resistors: * 2x 22Ω (Gate resistors) * 2x 10kΩ * 1x 4.7kΩ (for frequency adjustment) * Capacitors: * 1x 1000µF 25V (Filtering) * 1x 104 (100nF) Ceramic * 1x 2.2µF Electrolytic * Diodes: 2x 1N4148 * Potentiometer: 1x 50kΩ (To fine-tune output voltage/frequency)

Tools & Hardware: * Custom PCB * Heatsinks (Aluminum, for MOSFETs) * 12V DC Power Source (Li-ion battery pack or Lead-acid battery) * Soldering Iron and Solder Wire * Multimeter (For testing)

Step 1: Circuit Design and PCB PreparationThe heart of this inverter is the TL494 Pulse Width Modulation (PWM) IC. Unlike simple oscillators, this IC provides a precise frequency (50Hz/60Hz) and dual-channel output to IR2110 to drive the MOSFETs in a "push-pull" configuration.For a professional build, it is recommended to use a custom PCB. You can export the Gerber files and order them from a service like JLCPCB. This ensures the high-current traces are thick enough to handle the 300W load without overheating.

Step 2: Soldering the Small ComponentsStart by soldering the components with the lowest profile to keep the board stable: * Resistors & Diodes: Place the resistors and the 1N4148 diodes. * IC Socket: Always use an IC socket for the SG3525. This prevents heat damage to the chip during soldering and allows for easy replacement. * Capacitors: Solder the ceramic and electrolytic capacitors. Ensure the polarity of the electrolytic capacitors is correct (the stripe indicates the negative lead).

This project was made possible by JLCPCB, a leading manufacturer of high-quality PCB prototypes and SMT assembly services.New User Promotion: Register via the link below to receive $135 in coupons for your first orders.Special Offer: Get your PCB and SMT Stencil for only $5 (for sizes up to 100x100mm).I used JLCPCB. They have an incredible deal where you can get 5 PCBs and a Solder Stencil for just $5.Using a single Gerber file to order both the board and the stencil makes the assembly much cleaner. If you're starting a new project, you can Sign up here to get Free Coupons for your first order.

link: $5 for 5 PCBs and One Stencil, One Gerber File to

Order Both, Sign up here to Get Free

Coupons: Free Coupons From JLCPCB

Added Power MOSFETs and Resistors

Step 3: Installing the MOSFETs and HeatsinksThe IRF3205 MOSFETs handle all the current from the battery. At 300W, they will generate significant heat. * Apply a small amount of thermal grease to the back of the MOSFETs. * Secure them to the aluminum heatsinks tightly. * Solder the MOSFETs to the PCB. Note: Ensure the heatsinks do not touch each other if they are electrically "live" via the MOSFET drain, or use mica insulators.

Step 4: Connecting the TransformerThe transformer steps up the low-voltage AC generated by the MOSFETs to 220V. * Primary Side: Connect the Center Tap of the transformer to the Positive (+) input of the 12V battery. Connect the two side wires of the primary to the MOSFET drain outputs on the PCB. * Secondary Side: These two wires will provide the 220V AC output. Connect these to an AC socket or terminal block.

Step 5: Testing and CalibrationBefore plugging in expensive appliances, we must test the output: * Connect a 12V battery to the input. * Using a multimeter (set to AC Voltage), measure the output terminals. It should read between 220V and 240V. * Frequency Check: If your multimeter has a frequency setting, check for 50Hz or 60Hz (depending on your region). Use the onboard potentiometer to adjust this if necessary. * Load Test: Connect a small 10W LED bulb. If it lights up steadily, the circuit is working. You can then test with higher loads like a table fan.Step 6: Final AssemblyOnce the circuit is verified, mount the PCB and transformer inside a non-conductive (plastic or wood) or grounded metal enclosure. Ensure there is adequate ventilation or a small DC fan to keep the MOSFET heatsinks cool during extended use.

⚠️ Safety Warning * Lethal Voltage: The output of this circuit is 220V AC, which can be fatal. Never touch the output terminals while the battery is connected. * Battery Safety: Use a fuse (30A-40A) between the battery and the inverter to prevent fire in case of a short circuit. * Polarity: Connecting the 12V battery in reverse will instantly destroy the MOSFETs and the IC. Double-check your connections!