According to the Three R’s slogan “Reuse, Reduce, Recycle”, we must be conscious to save our planet from electronic waste. Sometimes we have a dead cell phone, but the battery is in good working order. The circuit given here is used to utilize battery for mini candle light using high brightness LEDs.
The main part of the circuit is IC MC34063A. It is a monolithic controller consisting of an internal temperature compensated voltage reference, a comparator, a controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This IC is specifically designed to be incorporated into voltage step-up and step-down and inversion applications with a minimum number of external components.
CIRCUIT AND WORK
The circuit of this circuit is given in the circuit diagram section.
It is built around the MC34063A monolithic DC to DC converter (IC1), Schottky barrier diode (D1), four 5mm tall bright white LEDs, and a few other components.
Here, IC1 is configured in advanced configuration to drive four high brightness 5mm white LEDs from an old cell phone battery. The 33 ohm resistor R4 limits the current flowing through the LEDs. Capacitor C2 determines the operating frequency of the IC and resistors R3 and R5 determine the output voltage.
The output voltage can be calculated using the formula.
Vout = 1.25 (1+ (R2/R1))
Where, R1 is R5 and R2 is R3 in this circuit
When switch S1 is closed, IC1, inductor L1 and Schotkky barrier diode D1 perform a step-up operation and the LEDs (LED1-LED4) light up. IC 78S40 can be used in place of MC34063A. Any Schotkky barrier diode works well in this circuit. By using a 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 a few more components.
Circuit diagrams
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