This is a 60 Watts inverter circuit diagram which using a couple power transistor of 2N3055 for final amplification. Actually, the circuit is capable of driving medium loads of the order of 40 to 60 watts working with battery of 12V, 15 Ah or greater capacity. This inverter will convert 12V DC input to turn into 230V AC in output.
Transistors T1 and T2 (BC548) form a 50Hz multivibrator. For getting proper frequency, the values of resistors R3 and R4 may possibly need to be changed after testing. The complementary outputs from collectors of transistors T1 and T2 are given to PNP darlington driver stages formed by transistor pairs T3-T4 and T6-T7 (utilising transistors BD140 and 2N6107). The outputs from the drivers are fed to transistors T5 and T8 (2N3055) connected for push-pull operation.
Somewhat greater wattage could be achieved by increasing the drive to 2N3055 transistors (by lowering the value of resistors R7 and R8 while increasing their wattage). Appropriate heatsinks could be utilized for the output stage transistors. Transformer X1 is a 230V primary to 9V-0-9V, 10A secondary implemented in reverse.
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