It is easy to make a sine-wave oscillator that has low output power. If you feed it to a power amplifier then the amplifier will make a lot of heat and most of the battery power will be wasted.

It is easy to convert a square-wave to a sine-wave at low power.

A sine-wave inverter uses a high frequency oscillator, a small high frequency transformer and Mosfets to make a suitable high voltage then rectifies and filters it. Then it uses a microcontroller to make pulse-width-modulation at 50Hz or 60Hz and feeds an H-bridge with high voltage switching Mosfets that produce the sine-wave with many steps in it, then two small high frequency filters. Negative feedback is used to regulate the output voltage. A shutdown circuit works during over-current, over-temperature and low battery voltage.

Ask your teacher to give you a circuit of a sine-wave oscillator or pure sine-wave inverter.

Look in Google. There are links to hundreds of sine-wave oscillator circuits. You might even find the very complicated circuit for a pure sine-wave inverter.

I have decided to build the circuit with CD4047 together with CD4001 and IRFZ44. Hopefully, it i will be able to get the voltage and waveform that was required.

Just to clarify something, the resistor value that was input to CD4047, can i use a potentiometer instead of fixed value so as i can adjust the frequency accordingly? Furthermore, can i used a 9-0-9/230 with a rated of 36VA instead of 10-0-10/230 transformer. What will be the difference and if not, can i use a 12-0-12/230 transformer? Lastly, there is a capacitor that is connected in series to a resistor of 100/5W. What is the value of the capacitor, is it 220uF and also is it a AC or DC capacitor?

Hullo Audioguru, I have built that circuit but the output at pin 10 and pin 11 of the cd4001 is only 6V and you said mosfets turn on when there gate to source voltage is 10V how come these turn on at 6V could it be the reason why its output is low? I also used a 9V-0V-9V/ 230V transformer its no load current draw from the battery is 1ampere why is this? Thanks

Pin 10, 11 and 13 of the CD4047 and the outputs of the Cmos gates are a square-wave with a peak voltage of at least 12V and turn on the Mosfets perfectly. The average of 6V might show on a DC voltmeter. An ordinary AC voltmeter will not measure the peak voltage of a square-wave since they are made to measure a sine-wave which is very different.

The no load draw from the battery is only 12W which is low. The quality of the transformer affects how much is the battery current without a load.

Now you say the output is low. Was the voltage at the output low? What was the load? Did you measure the voltage with a True-RMS voltmeter because an ordinary voltmeter cannot measure these digital signals. accurately.

I have decided to build the circuit with CD4047 together with CD4001 and IRFZ44. Hopefully, it i will be able to get the voltage and waveform that was required.

Just to clarify something, the resistor value that was input to CD4047, can i use a potentiometer instead of fixed value so as i can adjust the frequency accordingly? Furthermore, can i used a 9-0-9/230 with a rated of 36VA instead of 10-0-10/230 transformer. What will be the difference and if not, can i use a 12-0-12/230 transformer? Lastly, there is a capacitor that is connected in series to a resistor of 100/5W. What is the value of the capacitor, is it 220uF and also is it a AC or DC capacitor?

Hi Goodman, R1 can be a 100k potrentiometer in series with 22k. C1 should be a metalized poly film type. A 36VA transformer is too small for a power inverter. In this 500W circuit the transformer should be 800VA. there should be a 100 ohm resistor in series with the positive supply to the ICs and a 15V zener diode and 0.1uf capaciroe to ground. change the 1k resistors to 100 ohms. A 9V-0-9V 1000VA transformer will be fine. Use only two Mosfets for a 250W inverter that uses a 400VA transformer.

Would this circuit: 200824215918_20081910308_Modified sine-wave inverter schematic.png

work for a small AC motor (4watts)? Am looking for an inverter circuit for 115vac/5VA that is kind to motors. Square wave inverters eat them for breakfast. Any suggestions?

The input is 60Hz/12vdc - so don't need the input circuit. Thanks for any help/suggestions! George

The modified sine-wave is really a modified square-wave. It might also eat your tiny motor.

Make a 5W power amplifier with a stepup transformer and feed it a sine-wave. There are hundreds of car radio amplifier ICs available. If you use a bridged amp then use a 6VAC transformer.