Mini Candle Light Using Old Mobile Phone Battery

According to the Three R’s slogan “Reuse, Reduce, Recycle”, we must get aware to save our planet from e-waste. Sometimes we have dead mobile phone but its battery is in good working condition. The circuit given here is used to utilize the battery for mini candle light using High bright LEDs.

The main part of the circuit is IC MC34063A. It is a monolithic controller which consists of an internal temperature compensated voltage reference, a comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This IC was specifically designed to be incorporated in step−down and step−up and voltage inverting applications with a minimum number of external components.

CIRCUIT AND WORKING

The circuit of this circuit is given in the circuit diagram section.

It is built around monolithic DC to DC converter MC34063A(IC1), Schottky barrier diode (D1), four 5mm high bright white LEDs and few other components.

Here, the IC1is configured in step-up configuration to drive four high bright 5mm white LED’s from an old mobile phone battery. The 33ohm resistor R4 limits the current flowing through the LEDs. The capacitor C2 determines the operating frequency of the IC and the resistors R3 and R5 determine the output voltage.

The output voltage can be calculated by using the formula.

Vout = 1.25 [1+ (R2/R1)]

Where, R1 is R5 and R2 is R3 in this circuit

When the switch S1 is closed the IC1, Inductor L1 and schotkky barrier diode D1 perform step-up operation and the LED’s (LED1- LED4) glows. IC 78S40 can be used in place of MC34063A. Any schotkky barrier diode works fine in this circuit. By using low ESR capacitor we can increase the efficiency of the circuit. This circuit can be converted into a small emergency light by adding a charger and few more components.