Simple 220V Inverter Circuit using 2N3055 Transistors

This article shows you how to build a powerful inverter circuit that can turn a 12V battery like a car battery into household electricity 220V.

It is easy to build, uses few parts, and is very efficient according to the author.

There should be safety regulations regarding using homemade inverters so be sure to check before you build one.

What is a 220V Inverter Circuit using 2N3055 Transistors:

A 220V inverter circuit using 2N3055 transistors is a design that converts a low voltage DC input typically 12V to a higher voltage AC output 220V.

The 2N3055 transistors act as power amplifiers to drive a transformer ultimately producing the desired output.

Circuit Working:

Parts List:

Using a Transistor Astable as the 50Hz Oscillator:

The entire design revolves around an astable multivibrator stage, comprising two low power general purpose transistors BC547 and associated components including electrolytic capacitors and resistors.

This stage generates the necessary 50Hz pulses to initiate the inverter operations.

The low current signals are then elevated by darlington configured driver transistors BD680 to higher current levels before being fed to the output transistors.

The output transistors, a pair of 2N3055 receive an amplified current drive from the driver stage and operate at high saturation and current levels.

This current is then alternately directed to the transformer windings resulting in the generation of the required 220V AC volts at the secondary of the transformer.

Power Output 100 watts with a single 2N3055 transistor on each channel.

Frequency 50 Hz, Square Wave.

Input Voltage 12V @ 5 Amps for 90 Watts.

Output Volts 220V or 120V (with adjustments).

Heatsink specifications for T3 and T4, T5 and T6 are also recommended.

Calculating Resistors and Capacitors for 50 Hz or 60 Hz Frequencies:

In this transistor based inverter circuit, the oscillator design is based on a transistorized astable circuit.

The resistors and capacitors associated with the transistor bases determine the output frequency.

Although correctly calculated for approximately 50Hz, if you wish to adjust the frequency according to your preference you can easily do so using the Transistor Astable Multivibrator Calculator.

Formulas and Calculations:

Formula for calculating Frequency of Oscillation:

f = 1 / T = 1 / 1.38RC

where,

• f: This is the astable multivibrators frequency, expressed in hertz Hz.
• T: This stands for the duration, expressed in seconds (s), of one full cycle of the output voltage waveform, which includes both the high and low states.
• R: This stands for the circuits resistance value, which is currently expressed in ohms Ω.
• C: This stands for the circuits capacitance value, expressed in farads F.
• 1.38: This particular formula for astable multivibrators uses this constant value.

In essence, the formula says that the frequency (f) is inversely related to the time constant (τ) multiplied by 1.38.

The product of resistance R and capacitance C yields the time constant (τ).

Calculations:

= 1/ (1.38 x 27000 x 4.7E-7)

= 57.10 Hz

Consequently, the astable multivibrators predicted frequency is 57.10 Hz based on the formula and the provided component values.

Note:

This figure an approximation, the following reasons might cause a tiny variation in the circuits actual frequency:

• Non ideal transistor behavior
• Tolerances for components (differences in the real values of capacitance and resistance)
• Unwanted resistances and capacitances in the circuit design
• Practical measurements or circuit modeling tools can be useful for more accurate frequency estimation.

How to Build:

Building the simple 90 watt inverter circuit involves following the schematic and assembling the components in a systematic manner.

• Carefully study the provided diagram to understand the placement and connection of each component.
• Place the transistors BC547,BD680 and 2N3055 on the PCB as per the diagram.
• Connect resistors and capacitors according to their values and positions on the schematic.
• Use the correct resistor values as specified.
• Connect the transformer as per the schematic ensuring the correct winding connections.
• The transformer specifications must match the design requirements.
• Attach heatsinks to T3and T4, T5 and T6 transistors to dissipate heat effectively during operation.
• Connect the 12V power supply to the circuit.
• Ensure it can deliver at least 5 Amps.

Testing:

• Power on the circuit and use an oscilloscope or frequency meter to check the output frequency.
• Adjust resistors and capacitors if needed to achieve the desired 50Hz frequency.

Output Connection:

• Connect the output terminals to a load or device requiring 220V AC power.

Further Adjustments:

• Fine tune the circuit if necessary for optimal performance.
• Monitor temperature and stability during operation.

Safety Precautions:

• Exercise caution when working with high voltages.
• Ensure all connections are secure and insulated.
• Follow safety guidelines when soldering and handling electronic components.

Conclusion:

Remember, building electronic circuits requires attention to detail precision in soldering, and careful testing.

If you are unfamiliar with electronics, seek assistance from someone experienced or consider consulting a professional.

Always maintain safety during the construction and testing phases.

References:

Need help on 2N3055 12v DC to 220v AC Inverter Circuit