ABSTRACTTITLE: 12V DC to 230V AC / 60W Inverter Problem Description: This project is aimed to use the home appliances even in the absence of main power supply. This is a transistorized inverter circuit capable of driving medium loads of the order of 40 to 60 watts using battery of 12V. This inverter will convert 12V DC input to become 230V AC in output. This inverter circuit consists of various sections: • • • • Multi vibrator section Darlington pair section Pull push section Output section Multi vibrator section: A Multi vibrator is an electronic circuit used to implement a variety of simple two-state systems such as oscillators, timers and flip-flops. It is characterized by two amplifying devices (transistors, electron tubes or other devices) cross-coupled by resistors and capacitors. Multi vibrator used in the inverter circuit is an Astable Multi vibrator. Astable multi vibrator is not stable in either state. It continuously oscillates from one state to the other. Due to this, it does not require any input (Clock pulse or other). General circuit of Astable Multi Vibrator Transistors T1 and T2 (BC548) form a 50Hz multi vibrator. and the other supplying or sourcing current to the load from a positive power supply. one dissipating or sinking current from the load to ground or a negative power supply. Pull push section: A push–pull output is a type of electronic circuit that can drive either a positive or a negative current into a load. Darlington pair section: The output of Multi vibrator will be a weak signal. In general a varying current is applied to the primary windings and an induced varying voltage is obtained from the secondary windings. Darlington pair is a compound structure consisting of two bipolar transistors connected in such a way that the current amplified by the first transistor is amplified further by the second one. It is usually realized as a complementary pair of transistors. Thus it has to be amplified sufficiently. A Transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. General circuit of Darlington Pair 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 (utilizing transistors BD140 and 2N6107). This configuration gives a much higher current gain than each transistor taken separately. Output section: This section contains a Transformer. If a load is connected to the secondary.In the inverter circuit. For this purpose Darlington pair section is used. . an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. The outputs from the Darlington pair drivers are fed to transistors T5 and T8 (2N3055) connected for push-pull operation. Push pull section is used to drive the current into the load. home appliances can be operated by using the designed inverter. 10A secondary used in reverse. • It can be used in Uninterruptible power supplies (UPS). This electricity can be used to home appliances satisfactorily. Finally the transformer is used in reverse manner to obtain a steady 230-240 volts. The circuit contains various sections.But in this circuit transformer is used in a reverse manner. Applications: • This inverter converts the DC electricity from 12 volts battery to AC electricity. An uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when main power is not available. Circuit diagram: . Division of Project: Circuit diagram. Suitable heat sinks can also be used for the output stage transistors. So it can operate any AC equipment designed for mains operation. State of the Art: In the absence of main power supply. Inverter circuit uses the concept of using transformer in the reverse manner. Multi vibrator section is used to produce the oscillations. functioning and working by M B Yashwanth Kumar and P Krishna chaitanya while testing done by Anil Kumar Karnati and Documentation done by P Prashanthi. The electricity obtained is about 230-240 volts. Thus obtained oscillations are amplified by Darlington pair section. • It provides high frequency main AC power for use in induction heating. Transformer X1 is a 230V primary to 9V-0-9V. 60 Hz ac electricity. com Batch No: 8 Name & Roll Number: M B Yashwanth Kumar 07881A04C0 P Krishna Chaitanya Anil Kumar Karnati P Prashanthi 07881A0488 07881A0463 07881A0499 .com 3. www.electronicsforu.ICJournal. It is cost-efficient and easy to carry along.projectguidance.com 2.Conclusion: The simplicity of the circuit makes it highly user-friendly and easy to use. http://electronicsprojects.circuitstoday.com 4. www. References: 1. www. It is specifically designed for home appliances. _______________________________ Ch. Srinivas Rao Associate Professor .