modified sine wave for beginners at low cost

SIMPLE WAY OF DOING INVERTER

Hello, here is a simple way to make a home/office modified sine wave inverter that can power various appliance such as bulbs, TV. A modified sine wave inverter gives an output which is intermediate between the square wave and pure sine wave.

For a modified sine wave inverter, we need two inverted square signal to switch the mosfets to generate these signals we make use of ‘cd4047’ multi-vibrator i.c. we use it in a stable mode which gives a buffered output so there is no need for impedance matching. In a stable mode it generate square wave of exactly 50% duty cycle at its pin 10 and its inverted signal on pin 11. It also generates frequency double to that of pin 10 at pin 13.

                                                                WORKING PRINCIPLE

We gave a pwm signal to the pair of MOSFETS connected in a push pull configuration. When the first side of the mosfet  say[side A] is turned on by high input, then the second side of the mosfet say [side B] turns off at that time because on its input we had an inverted signal with some delay. The delay is used so that one of the mosfets get time to turn off before second one turns on. In this mode, the current flows from source to mosfet side A. when the first signal goes low then the second signal becomes high and side B of the mosfet turns on resulting in current flowing from source thus we get a high voltage output at the transformer primary. A 10k ohms resistor from gate to source is important because when the input signal goes to zero, the mosfets may not completely turn off because of the capacitance between gate and source so this resistance makes sure that the signal is fully grounded. The threshold voltage to turn on mosfet is approximately 4v. we are driving mosfets with 12v signal so that mosfets is completely turned on otherwise it will lead to power dissipation….

Below is a simple schematic diagram that can help in your design   

 

FIG1 : CD4047 OSCILLATOR CIRCUIT DIAGRAM

 Part list include: 

• 104 cap
• 5k variable resistor
• cd4047
• Tip41c
• 8v zener diode
• 2 * 220ohms resistor
• 1kohms resistor
• irfp 250n
• 470ohms resistor * 6
• 10k resistor * 2
• 12v big inverter transforme {center tap} 

watch out for more circuit diagram especially oscillator using sg3524 ic.

for more info, you can contact me on 08138110639 or 07018399701 or mail @ jvertectelect@gmail.com