Simple 220V Inverter Circuit using 2N3055 Transistors

This article shows 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.

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

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

Using 2N3055 transistors a 220V inverter circuit converts a low voltage DC input generally 12V into a higher voltage AC output of 220V.

By powering a transformer the 2N3055 transistors function as power amplifiers finally generating the required output.

Circuit Working:

Parts List:

Using a 50Hz oscillator with a transistor astable:

With two low power general purpose transistors BC547 as well as related parts such electrolytic capacitors and resistors the entire design focuses around an astable multivibrator stage.

This step produces the 50 Hz pulses required to start the inverters duties.

Before being sent to the output transistors the low current signals are first raised to higher current levels by the BD680 driver transistors with a darlington configuration.

The output transistors a pair of 2N3055s function at high saturation and current levels after receiving an amplified current drive from the driver stage.

The necessary 220V AC volts is generated at the transformers secondary by constantly directing this current to the transformer windings.

Each channel has a single 2N3055 transistor with a 100 watt power output.

50 Hz square wave frequency.

90 Watts at 12V and 5 Amps is the input voltage.

220V or 120V output voltages with modifications.

Also recommended are the heatsink specifications for T3, T4, T5 and T6.

The calculation of capacitors and resistors at frequencies of 50 Hz or 60 Hz:

The oscillator design of this transistor based inverter circuit comes from a transistorized astable circuit.

The output frequency is controlled by the resistors and capacitors connected to the transistor bases.

The Transistor Astable Multivibrator Converter makes it simple to change the frequency to a desired level even if it is correctly measured for about 50 Hz.

Formulas and Calculations:

Formula for calculating Frequency of Oscillation:

f = 1 / T = 1 / 1.38RC

where,

• f is the astable multivibrators frequency expressed in hertz Hz.
• T 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 stands for the circuits resistance value which is currently expressed in ohms Ω.
• C stands for the circuits capacitance value expressed in farads F.
• 1.38 is particular formula for astable multivibrators uses this constant value.

The formula simply indicates that the frequency (f) and the time constant (τ) multiplied by 1.38 are inversely connected.

The time constant (τ) is calculated by multiplying resistance R by capacitance C.

Calculations:

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

= 57.10 Hz

Thus using the calculation and the given component values the astable multivibrators expected frequency is 57.10 Hz.

Note:

This value is an estimate and the actual frequency of the circuit could differ somewhat for various reasons mentioned below:

• Transistor behavior that is not the perfect
• Component tolerances like differences in capacitance and resistances actual values
• In the circuit design unneeded capacitances and resistances
• For a more accurate calculation of frequency actual measurements or circuit model techniques can be helpful.

How to Build:

Check the provided diagram carefully to understand where each component lies and how it is connected.

• As shown in the diagram arrange the transistors BC547, BD680 and 2N3055 on the PCB.
• As shown by their values and positions on the diagram connect the resistors and capacitors.
• As advised use the correct resistor values.
• Make sure the winding connections are accurate by connecting the transformer according to the design.
• The design specifications and the transformer details must match up.
• When operating connect heatsinks to transistors T3, T4, T5 and T6 to properly dissipate heat.
• Connect the circuit to the 12V power source.
• Check to see whether it can supply at least 5 amps.

Testing:

• Switch the circuit on then verify the output frequency with a frequency meter or oscilloscope.
• If necessary adjust the resistors and capacitors to reach the required frequency of 50 Hz.

Connection for Output:

• Connect a load or other equipment that needs 220V AC power to the output terminals.

Additional Modifications:

• If required fine tune the circuit for best results.
• during operation keep an eye on stability and temperature.

Safety Measures:

• When handling high voltages take precaution.
• Make sure every connection is insulated and safe.
• When handling and connecting electrical components follow all security rules.

Conclusion:

Keep in mind that designing a electronic circuits requires thorough testing, soldering accuracy and care for every little thing.

Seek help from an expert or think about speaking with a professional if you are not comfortable with electronics.

Throughout the testing and building stages always keep yourself safe.

References:

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