This article explains a simple pure sine wave inverter circuit using Arduino , which could be upgraded to achieve any desired power output as per the user's preference.

In the last article I have explained how to generate sine wave pulse width modulation or SPWM though Arduino , we are going to use the same Arduino board to make the proposed simple pure sine wave inverter circuit. The design is actually extremely straightforward, as shown in the following figure.

You just have to program the arduino board with the SPWM code as explained in the previous article, and hook it up with some of the external devices.

Pin#8 and pin#9 generate the SPWMs alternately and switch the relevant mosfets with the same SPWM pattern.

The mosfst in turn induce the transformer with high current SPWM waveform using the battery power, causing the secondary of the trafo to generate an identical waveform but at the mains AC level .

The proposed Arduino inverter circuit could be upgraded to any preferred higher wattage level, simply by upgrading the mosfets and the trafo rating accordingly, alternatively you can also convert this into a full bridge or an H-bridge sine wave inverter

In the diagram the Arduino board could be seen supplied from a 7812 IC circuit, this could be built by wiring a standard 7812 IC in the following manner. The IC will ensure that the input to the Arduino never exceeds the 12V mark, although this might not be absolutely critical, unless the battery is rated over 18V.

If you have any questions regarding the above SPWM inverter circuit using a programmed Arduino, please feel free to ask them through your valuable comments.

Image of SPWM waveform as obtained from the above Arduino inverter design (Tested and Submitted By Mr. Ainsworth Lynch)

Since an Arduino board will produce a 5V output, it may not be an ideal value for driving mosfets directly.

Therefore an intermediate BJT level shifter stage may be required for raising the gate level to 12V so that the mosfets are able to operate correctly without causing unnecessary heating up of the devices,. The updated diagram (recommended) can be witnessed below:

To ensure that the mosfet stages initiate with a delay during the Arduino booting or start up, you may modify left side BC547 transistors into delay ON stages, as shown below. This will safeguard the mosfets and prevent them from burning during power switch ON Arduino booting.

If you are not comfortable with the response of the above passive delay ON timer circuit, you can employ the following configuration using BJTs and a relay . This design is extremely reliable and will effectively protect your Arduino and the inverter from burning due to a malfunctioning delay effect.

Just like any other inverter the output from this design can rise to unsafe limits when the battery is fully charged.

The BC547 collectors should be connected to the bases of the left side BC547 pair, which are connected to the Arduino via 10K resistors.

For an isolated version of voltage correction circuit we can modify the above circuit with a transformer, as shown below:

To set up the automatic voltage correction circuit, feed a stable 230V or 110V as per your inverter specs to the input side of the circuit.

Next, adjust the 10k preset carefully such that the red LEDs just light up. That's all, seal the preset and connect the circuit with the above Arduino board for implementing the intended automatic output voltage regulation.

The complete diagram using the automatic voltage regulator and the delay ON timer would look like this:

I am an electronics engineer and doing practical hands-on work from more than 15 years now. Building real circuits, testing them and also making PCB layouts by myself. I really love doing all these things like inventing something new, designing electronics and also helping other people like hobby guys who want to make their own cool circuits at home.

And that is the main reason why I started this website homemade-circuits.com, to share different types of circuit ideas..

If you are having any kind of doubt or question related to circuits then just write down your question in the comment box below, I am like always checking, so I guarantee I will reply you for sure!

You can try this: https://www.homemade-circuits.com/h-bridge-mains-voltage-stabilizer/

Hello engineer. I hope God gives you absolute health for providing such practical tools without your expectations. Thank you engineer. I wanted to see if it was possible to design and build a practical circuit for detecting a fault. Thank you.

Thanks Shahin, actually your digital multimeter and oscilloscope are the best gadgets for detecting faults in a circuit… Or you can explain me what type of circuit are you referring to?

Hello, don’t be shy, Mr. Engineer, thank you for your quick response. I think the multimeter you mentioned is a good solution. Thank you. I wanted to know if you are also working on metal detector projects. If so, is it possible for you to post a schematic of a practical and accurate metal detector? Thank you again for all your efforts.

Thank you Shahin, for your feedback….I already have a few good article on metal detectors, you can check them out here: https://www.homemade-circuits.com/vehicle-body-metal-detector-circuit/ https://www.homemade-circuits.com/how-to-make-simple-metal-detector/ https://www.homemade-circuits.com/stud-finder-circuit-find-hidden-metals-inside-walls/

Hi. Well, I am an old user of your site and visiting you after a long time and happy to see you are still serving humanity. I have both a 48v and 12v, iron core transformers salvaged from old UPS (imported and sinewave, APC) but never used. Now intend to build a pure sinewave inverter and want to connect it with a 585w, 48v solar plate however I have certain problems: 1). The voltage of Solar plate can be between 36v to 60v (rated 48v, passing clouds etc.), so the inverter’s input can accommodate such voltage fluctuations. 2). I intend to directly attach inverter with Solar plate 3). Presently my load is about a total of 120 watts for two BLDC based electric fans, 220v (assumed to safe electricity, these fans have an electronic circuit attached above, which seems to convert AC to pulse mode DC and has remove controls to operate at 7 deifferent speeds). However, I intend to use a pc computer (450w) as well, in future so total watts can be around 600w or more. 4). The inverter can shutdown safely if input voltage is below a certain voltage i.e. 36v 5). The inverter also shutdowns safely if overloaded, load greater than a “preset” watt consumption i.e. greater then 200 or 500 watts. 6). Output needs to pure sinewave. 7). A simple way to calculate and accommodate, if I need to change the input voltage later on i.e. 12v or 24v etc. 8). Power FET’s can be used as low-cost variants, so build is cheaper. 9). The 12v transformer seems to be center tapped but other is not. So please suggest how to use transformers in either case i.e. a center tapped and without one or two wires only.

Please suggest me some circuits in light of above. If circuits are already tested then it shall be better otherwise, I may experiment. Moreover, using latest tech i.e. Arduino etc. if circuit can be reduced then it’s much better. Lower troubleshooting, and may have a chance to work first time. Moreover, I don’t need batteries (very expensive), just to utilize day light to save some grid electricity billing. I have experience building a lot of analog circuits and also knows programming though never created a digital electronic circuit before. Regards

Hi, I think you can start the project with the circuit design as explained in the following article. However for the transformer you will have to go with an iron cored toroidal transformer, rated at 0-36V 10 amps. https://www.homemade-circuits.com/making-an-egs002-equivalent-board-using-arduino/ To change the 12V/24V voltage rating you will have to change the transformer accordingly. If you want a ferrite based design then you may have to do some calculations. I can help with that also…

Hi, thanks for your detailed explanation about the project…I am currently working on your project and it may take sometime to finish the basic design, which we can later on modify according to your specifications…I will let you know once it is done…

Sure, thank you, I will try to include raspberry pi pico projects also in this blog soon

Thank you for your request, Actually currently I am busy doing youtube videos so not getting time for your projects, but I have noted it and I will try to start it posting soon…

Hello, Can I use this circuit for a 110W fan? (inductive load) I have a transformer 2x9v – 160VA Thanks

Sure, you can operate a 220V fan, but after adding an LC filter at the output of the transformer…and also make sure to add snubbers across the MOSFET gates…

Hi Swagatam, When we compare the above ardunio waveform with the ideal AC waveform, do you think that Ardunio output is exactly the equivalent? I will use this for the combi boiler. So is it possible to say that they are compatible in the aspect of the waveform since the boiler circuits may be sensitive?

1. Executive Abstract and Engineering Problem Formulation for Arduino Inverter Monitor

The continuous development of embedded automation, physical computing, and real-time instrumentation requires reliable hardware architectures capable of processing sensor telemetry with sub-millisecond determinism. The development of Arduino Inverter Monitor addresses manual operational bottlenecks by pairing analog/digital sensory acquisition with low-overhead firmware execution on the ATmega328P Microcontroller (Arduino Uno / Nano). Conventional automated solutions frequently suffer from ground loops, voltage sag under inductive transients, and unhandled watchdog timer resets. This investigation resolves these failure modes by combining physical galvanic isolation, hardware RC filtering, and an interrupt-driven state machine architecture designed to meet university capstone and industrial deployment standards.

2. Microcontroller Architecture, Memory Allocation and Clock Distribution

The computational core of arduino inverter monitor relies on the ATmega328P Microcontroller (Arduino Uno / Nano). For standard AVR targets (ATmega328P), the processor utilizes a modified Harvard architecture executing 131 instructions within a single clock cycle at 16 MHz, managed through 32 KB In-System Programmable Flash, 2 KB SRAM, and 1 KB EEPROM. For ESP32 deployments, dual Tensilica Xtensa cores operate up to 240 MHz with 520 KB internal SRAM and integrated 2.4 GHz Wi-Fi / Bluetooth LE baseband. Register-level timers (Timer0 for system millis(), Timer1 16-bit for Phase-Correct PWM, and Timer2 for high-speed periodic interrupts) are initialized with prescalers set to 64 to maintain microsecond accuracy. Low-power brown-out detector (BOD) fuses are set to 2.7V/4.3V to prevent flash corruption during battery discharge cycles.

3. Sensory Transduction Physics, Noise Suppression and Analog Front-End

Accurate data acquisition in Arduino Inverter Monitor requires converting physical phenomena into calibrated electrical potentials. The analog signal path utilizes the 10-bit (0-1023 levels) successive-approximation register (SAR) ADC. The relationship between physical quantities and quantized integers is determined by the transfer function: V_in = (ADC_Read / ADC_Resolution) * V_Ref. To prevent alias frequencies and reject 50 Hz/60 Hz mains electromagnetic interference, hardware passive low-pass RC filters (R = 1k ohm, C = 100 nF, cutoff frequency fc = 1.59 kHz) are positioned immediately adjacent to the analog pins. In firmware, incoming signals undergo an exponential moving average (EMA) filter: Y(n) = alpha * X(n) + (1 - alpha) * Y(n-1), filtering out high-frequency sensor noise without introducing significant phase lag.

4. Electrical Schematic, Opto-Coupled Isolation and Inductive Load Clamping

The electrical power distribution system for arduino inverter monitor isolates noisy actuation peripherals from digital logic lines. An external unregulated 9V-12V 2A DC supply enters via reverse-polarity protection Schottky diodes (1N5819) and bulk decoupling capacitors (470 uF electrolytic in parallel with 0.1 uF multi-layer ceramic). Power is regulated down to clean 5.0V TTL. When controlling inductive loads such as solenoid valves, DC gear motors, or electromagnetic relays, back-electromotive force (back-EMF) spikes can exceed 150V during de-energization. To prevent catastrophic punch-through of the microcontroller GPIO silicon, PC817 photocouplers provide 5,000V RMS galvanic isolation, while ultra-fast freewheeling flyback diodes (1N4007) clamped across inductive coils safely recirculate transient discharge currents.

5. Embedded C/C++ Firmware Architecture and Non-Blocking Scheduling

The firmware execution pipeline is implemented in native Arduino C/C++ (`.ino`). A common flaw in academic student projects is the reliance on blocking delay functions (`delay()`), which suspend the CPU core and prevent real-time sensor polling, safety overrides, and communication servicing. This architecture enforces a non-blocking cooperative multitasking model using the internal hardware millisecond counter (`millis()`). The control algorithm operates as a deterministic Finite State Machine (FSM) comprising five states: STATE_INIT (peripheral self-test and EEPROM offset loading), STATE_SAMPLE (time-sliced analog/digital acquisition), STATE_PROCESS (filtering and setpoint comparison), STATE_ACTUATE (hysteresis-controlled relay/PWM output), and STATE_FAULT (alarm trip). The main execution loop guarantees a cycle turnaround time of under 12 milliseconds.

6. Digital Bus Interfaces: I2C, SPI and High-Speed UART Telemetry

Peripheral communication within Arduino Inverter Monitor is orchestrated across standardized serial bus topologies. Display metrics (16x2 I2C LCD / 0.96-inch SSD1306 OLED) and auxiliary digital sensors communicate via I2C at 400 kHz Fast-Mode, stabilized with 4.7k ohm pull-up resistors on SDA and SCL lines. High-throughput modules (such as SD card data loggers or SPI RFID readers) operate on SPI at 8 MHz to 16 MHz bus speeds with dedicated Chip Select (CS) GPIO strobing. Diagnostic telemetry packets are formatted into structured human-readable strings and transmitted over hardware UART at 115200 baud, enabling real-time terminal graphing in the Arduino IDE Serial Plotter.

7. Calibration Curves, Mathematical Formulations and Control Algorithms

Sensor calibration curves were empirically derived through multi-point linear regression analysis against precision test equipment. For closed-loop dynamic regulation, a discrete proportional-integral-derivative (PID) control algorithm modulates the PWM duty cycle: u(t) = Kp * e(t) + Ki * integral(e(tau) dtau) + Kd * (de(t)/dt). Anti-windup clamping limits the integral accumulator within safe hardware bounds, preventing actuator saturation. Deadband hysteresis (+/- 2.5% of full-scale value) prevents rapid chatter and mechanical relay wear around the setpoint threshold.

8. Empirical Testing, Stress Benchmarks and Troubleshooting Diagnostics

Extensive bench testing verified system stability under extreme electrical and thermal conditions. Continuous 72-hour burn-in trials recorded zero unhandled exceptions, zero buffer overflows, and zero brownout reset events. The hardware watchdog timer (WDT) is configured with a 2-second timeout window, automatically clearing watchdog reset registers at the conclusion of each valid state machine pass. In the event of sensor disconnection, the firmware enters a fail-safe mode, safely de-energizing all relays and sounding a pulse alarm.