CCFL TUBE TESTING CIRCUIT DIAGRAM

 

CCFL TUBE TESTING CIRCUIT DIAGRAM 

This circuit is an inverter designed to power a CCFL (Cold Cathode Fluorescent Lamp), often used for testing such lamps. It is built around the versatile NE555 timer IC.

Here is a breakdown of the key components and the circuit's function:

⚡️ Circuit Function and Design

The primary function of this circuit is to convert the low-voltage DC (6V) from the battery into the high-voltage AC required to ignite and run a CCFL.

 * Oscillator (IC1 - NE555): The NE555 timer is configured as an astable multivibrator (oscillator).

   * The timing components, R2 (1k\Omega), R3 (2.7k\Omega), and C2 (0.1\mu F), determine the frequency and duty cycle of the square wave output at Pin 3. This square wave is essential for driving the transformer.

 * Switching/Driver Stage (T1 - MOSFET): The output from the NE555 (Pin 3) drives the gate of the MOSFET (T1 - IRF512/IRF830).

   * The MOSFET acts as a switch, rapidly turning the current through the primary coil of the transformer X1 on and off according to the oscillator frequency. This high-frequency switching is what induces the high voltage in the secondary coil.

 * Voltage Step-Up (X1 - Transformer): This is a standard mains transformer used in reverse.

   * P (Primary): The coil labeled 'P' (originally the 230V primary) is now used as the secondary to output the high voltage for the CCFL.

   * S (Secondary): The coil labeled 'S' (originally the 6V, 250mA secondary) is now used as the primary and is connected in series with the MOSFET (T1).

   * The turns ratio steps the 6V pulses up to a much higher AC voltage (hundreds of volts) across the 'P' winding, which is then connected to the CCFL.

⚙️ Operating Controls and Indicators

 * S1 (Push-to-On Switch): This is the TEST switch. Pressing it connects the 6V battery to the circuit, initiating the CCFL test. This suggests the circuit is momentary-use, likely to save battery life.

 * LED1 (Power On): This LED acts as a visual indicator that the circuit is powered and receiving voltage when S1 is pressed.

 * R1 (1k\Omega): This resistor limits the current flowing through LED1, protecting it from damage.

 * C1 (100\mu F, 25V): This large electrolytic capacitor acts as a decoupling/filter capacitor across the power rails, stabilizing the DC voltage supply for the NE555 and the entire circuit.

 * C3 and C4 (0.01\mu F): These are small decoupling/bypass capacitors used to ensure stable operation and filter noise at specific pins of the NE555 (Pin 5 - Control Voltage, and Pin 1/4/8 - general supply bypass).

 * C5 (0.01\mu F): This capacitor is connected across the output winding ('P') of the transformer, likely for filtering or noise suppression of the high-voltage AC output.

In summary, the circuit uses the NE555 to generate a high-frequency pulse, which the MOSFET amplifies to drive a step-up transformer, resulting in the high AC voltage needed to light the CCFL.