This is second part of the tutorial on how to build a diy 12V DC to 220V AC inverter using TL494 PWM controller. Here I will be adding some components that remained to be connected in the unfinished circuit schematic of the inverter. These includes the ground connection of the common source of the pus pull MOSFET power driver stage, the pull-down resistors at each of the MOSFET gates, the gate discharge gates across the gate resistors.
Update:
See the 3rd part is here: How 12V to 220V AC TL494 Inverter Works - Simulation
The complete circuit schematic of the TL494 PWM controller-based Inverter is shown below.
Here I started by adding ground connection to the common source of the push pull MOSFET based power stage.
Next, I added the 10kohm pull down resistor (R7, R8, R9 and R10) to the gates of each IRFZ44N MOSFETs (Q3, Q4, Q5 and Q6). The pull-down resistors serve as a safety mechanism to ensure the MOSFETs remain in a known "off" state when the TL494 or driver stage is inactive. By referencing the gate to ground, they bleed off any leakage current or stray static charge that could prematurely trigger the gate. This prevents unintended conduction during circuit power-up, high-impedance states, or if the driver connection is lost, effectively protecting the inverter from erratic behavior or catastrophic short circuits.
After that, I added gate discharge diodes (D3, D4, D5 and D6) across each gate resistors (R3, R4, R5 and R6). The 1N4148 diodes function as a high-speed bypass for the gate resistors, enabling asymmetrical switching for the IRFZ44N MOSFETs. While the resistors limit the turn-on current to minimize EMI and ringing, the diodes provide a low-impedance path to rapidly evacuate stored gate charge during the turn-off cycle. This accelerated discharge ensures a crisp transition to the "off" state, which is critical in push-pull topologies to prevent shoot-through—a condition where both sides of the transformer conduct simultaneously—thereby reducing switching losses and protecting the power stage from thermal failure.
That's it, the circuit is complete. Now the TL494 inverter circuit is ready for simulation.
This TL494 inverter circuit design is explained in detail in the following video:
The next part of the tutorial link is also provided below which show simulation of the circuit that demonstrates how the circuit operates. There, I show 12V input voltage from lead acid battery connected to the J1 header, 220V bulb is connected at the output J2 connector header. The simulation will show that the bulb will glow at 220V. I will also show the measured output voltage using AC voltmeter, the signal waveform at the output on oscilloscope and the frequency of the output signal produced on frequency spectrum graph.
Also provided below is the link to the first part of the video where I have shown how I made the rest of the circuit is provided below. There in that webpage a video is available which shows the detailed steps I took to create the circuit. I also suggest looking at the TL494 IC explorer for easier design. Included in the link is also proteus simulation files which you can download for free.
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