This 100W inverter circuit works great for small loads like a fan or 2-3 bulbs/lamps. In this circuit as IC1 we used a CD 4047 IC to generate 100Hz frequency (180 degree out of phase). CD 4047 IC is from Texas Instruments. It is mostly used as Astable/Monostable signal generator device. In this circuit it is triggered as astable multivibrator by the capacitor C1 between the Pin 1 and 3 of CD4047. And VR1 is used to adjust the frequency of signal.
Four 2N3055 transistors are used to amplify the pulse trains that are pre-amplified by two TIP122 transistors. There used three transistors for each side (half cycle), one TIP122 & two 2N3055 transistor to drive the output transformer (TX in circuit). Four 2N3055 transistors are used as driving transistor. An inverters maximum output power depends on two factors; one is the max current rating of transformer’s primary winding and other factor is the current rating of driver transistors.
Transformer: Use a 12v-0-12v, 10A step-down transformer in reverse. That’s mean secondary winding (12v-0-12v) will be the primary and primary winding (220VAC side) will be the secondary (output). So that it will worked like a step-up transformer. You can also use a 5A transformer instead of 10A, if you couldn’t have 10A. But the output power will decrease to 60 Watt.
+12VDC: A good quality 12V car battery could be used for DC 12V.
VR1 = 250K (Variable resistor/POT)
R1, R2 = 4.7K-1/4W Resistor
R3, R4, R5, R6 = 0.1R-5W
C1 = 0.022uF
C2 = 220uF-25V
D1 = BY127 Diode
D2 = 9.1V Zener Diode
Q1, Q4 = TIP122 Transistor
Q2, Q3, Q5, Q6 = 2N3055 Transistor
F1 = 10A Fuse
IC1 = CD4047
TX = 12-0-12V, 10A Step-down Transformer