Simple 20 Watt Fluorescent Inverter Circuit

Imagine you have a regular battery like a car battery but you want to use it to power a fluorescent light.

That is not possible normally because the battery has low voltage.

This special circuit is like a magic box.

It uses a transformer, a transistor and a few other parts to take the low voltage from the battery and turn it into a high voltage zap that makes a fluorescent light work!

This zap is actually special electricity that goes back and forth AC instead of just one way DC like the battery.

Circuit Working:

Parts List:

In this article, the circuit can drive a 20 watt tube, here are some details about the circuit working:

The transformer is wound on a ferrite rod 10mm in diameter and 8cm long.

The wire diameters are not critical but the prototype used 0.61mm wire for the primary and 0.28mm wire for the secondary and feedback windings.

Do not remove the tube when the circuit is operating, as the spikes produced by the transformer will damage the transistor.

The circuit will draw approximately 1.5 amps on 12V making it more efficient than running the tubes from the mains.

A normal fluorescent lamp takes 20 watts for the tube and about 15 watts for the ballast.

Formulas:

Typically, we try to develop a high frequency oscillator to drive the fluorescent tube while designing a circuit for a single Bipolar Junction Transistor BJT and transformer in a fluorescent tube driver circuit.

Here is a basic formula for such a circuit:

(f)resonance frequency:

f = ​1​ / 2π√L * C

where,

• In the BJT base circuit, the oscillation frequency f is dictated by the capacitance C and the inductance L

The BJT oscillator generates a steady AC signal at a frequency appropriate for operating the fluorescent tube thanks to this resonance frequency.

Note:

With a single BJT and transformer, this technique offers a basic yet efficient way to drive a fluorescent tube.

It does this by emphasizing the resonance between the inductor and capacitor to produce steady oscillations at the required frequency.

How to Build:

To build a Simple 20 W Fluorescent Inverter Circuit follow the steps mentioned below for connections:

Transformer: 

• The primary winding is connected to the positive terminal of the battery through a safety resistor R3.
• The secondary winding is connected to the transistor Q1 collector.

Transistor: 

• The base is connected to a voltage divider network made up of resistors R1 and R2.
• The collector is connected to the secondary winding of the transformer.
• The emitter is connected to ground.

Capacitors: 

• C2 capacitor one end is connected through a feedback coil to base of transistor Q1.
• The other end is connected to ground.
• C1 capacitor is connected across the positive and negative terminals of the battery.

Fluorescent tubelight:

• Fluorescent tubelight is connected to the terminal of the secondary winding of the transformer.

Resistors  

• Resistors R1 and R2 connected from positive power supply to negative supply.
• Resistor R3 connected to the positive terminal of the battery as a safety resistor for testing.

Important Note:

• Use components with proper voltage and current ratings.
• Follow proper soldering techniques to avoid weak connections.
• Insulate exposed wires to prevent shorts.
• Never operate the circuit without a load fluorescent lamp connected, as it can damage the transistor.
• If you are uncomfortable with electronics seek help from someone experienced.

Conclusion:

A simple 20 watt fluorescent inverter circuit offers a way to power a fluorescent lamp from a low voltage DC source like a battery.

By using a transformer, transistor and a few other components, the circuit converts the DC voltage to a high voltage AC signal that can ignite the lamp.

While attractive for its simplicity building your own comes with safety risks due to the high voltages involved.

References:

Fluorescent lamp

Datasheet TIP3055