Here the 50W inverter circuit build based power MOSFET FQB45N03 and IC TL494. This inverter will convert 12-14V DC input from car battery, become 220V AC output with 50Hz sine wave frequency.

The main oscillator, a voltage reference and comparator collected on DA2. External elements DD1 and DD2 repeated internal structure of the TL494, in the part that works is unstable at low frequencies (false positive D-flip-flop).

Further, using the low-pass filter suppresses the upper harmonics of the PWM. LPF consists of two parts. First-DA1.1, with a smooth lowpass characteristic curves. Second-DA1.2 notch filter with a frequency of 150 Hz suppression. The analysis shows that the PWM contains only odd harmonics of the first and, because such a filter is enough to form a “beautiful” sine (oscillogram 2). And, as the level of the first harmonic is almost linearly dependent on porosity, we obtain a well-managed with precision sine constant component equal to 2.5 V. Further, in addition we get the inverse sine (Pin 14 DA1.4).

In DA3, DA5, VT1, VT2 assembled the first channel of the VLF class D. The second channel, respectively, collected on DA4, DA7, VT3, VT4. At the output of the first and second channels are formed antiphase sine wave VLF (oscillogram 3).

The output of the transformer, a diode bridge fed on the feedback output voltage. Thus the output voltage stabilisator.

**Inverter Circuit Specifications :**

- Input voltage 12 – 14V
- Output voltage 220VAC, tolerance +/-2V, freqency 50 Hz
- Maximum power 50W
- Efficiency … 90%.

__50W inverter circuit__ 12VDC to 220VAC based MOSFET FQB45N03, source: http://powersupply88.com/12220v-converter-with-sine-output.html