Here is a 100 Watt inverter circuit using minimum number of components. I think it is quite difficult to make a decent one like this with further less components. Here we use CD4047 IC from Texas Instruments for generating the 100 Hz pulses and four 2N3055 transistors for driving the load.
The IC1 CD4047 wired as an astable multivibrator produces two 180 degree out of phase 100 Hz pulse trains. These pulse trains are preamplified by the two TIP122 transistors. The out puts of the TIP122 transistors are amplified by four 2N3055 transistors (two transistors for each half cycle) to drive the inverter transformer. The 220V AC will be available at the secondary of the transformer. Nothing complex just the elementary inverter principle and the circuit works great for small loads like a few bulbs or fans. If you need just a low cost inverter in the region of 100 W, then this is the best.
Circuit Diagram with Parts List
The maximum allowed output power of an inverter depends on two factors. The maximum current rating of the transformer primary and the current rating of the driving transistors.
For example, to get a 100 Watt output using 12 V car battery the primary current will be ~8A, (100/12) because P=VxI. So the primary of transformer must be rated above 8A.
Also here, each final driver transistors must be rated above 4A. Here two will be conducting parallel in each half cycle, so I=8/2 = 4A .
These are only rough calculations and enough for this circuit.
Inside a huge PCB factory: https://www.youtube.com/watch?v=_XCznQFV-Mw
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