This is a circuit that is used as indicators or to provide illumination, LEDs are hard to beat in efficiency, reliability, and cost. White LEDs are rapidly gaining popularity as sources of illumination, as in LCD backlights, but with forward voltages typically ranging from 3 to 5V, operating them from a single cell presents obvious difficulties. This circuit is based on SN74AUC1G14 IC’s. This is the figure of the circuit.
The operation of the circuit begin, when you first apply battery power, Schottky diode D1 conducts, and the familiar Schmitt-trigger astable multi vibrator starts to oscillate at a frequency determined by timing components C2 and R1. When IC1’s output goes high, transistor Q1 turns on, and current begins to ramp up in inductor L1. At the end of tON, when the inverter output goes low, Q1 turns off, and the voltage across L1 reverses polarity. The resulting “flyback” voltage immediately raises Q1’s collector voltage above VBATT and forward-biases the LED and D2, which appear in series.
The operation of the circuit begin, when you first apply battery power, Schottky diode D1 conducts, and the familiar Schmitt-trigger astable multi vibrator starts to oscillate at a frequency determined by timing components C2 and R1. When IC1’s output goes high, transistor Q1 turns on, and current begins to ramp up in inductor L1. At the end of tON, when the inverter output goes low, Q1 turns off, and the voltage across L1 reverses polarity. The resulting “flyback” voltage immediately raises Q1’s collector voltage above VBATT and forward-biases the LED and D2, which appear in series.
