This is a design circuit for flasher LED. This circuit flashes an LED to provide a highly visible warning signal—for example, to indicate power on, battery low, or another eye-catching visual signal. However, white LEDs typically present a forward - voltage drop of 3 to 5V. This circuit is work with based on Logic IC and two transistor as main control. This is the figure of the circuit.
The principle of the operation in this circuit is when IC1’s output pulses high, Q2 turns on and saturates, sinking current, IL, through inductor L1. The inductor current ramps up at a rate determined mainly by VBATT; L1’s inductance; and Q2’s on-time, tON. During this interval, LED D1 and Q1’s base-emitter junction are reverse- biased. Provided that the inductor does not saturate, current IL ramps up linearly and reaches a peak value, IL(PEAK) at the end of the on-time. When IC1’s output goes low and Q2 turns off, L1 generates back EMF to forward-bias D1 and raises its anode voltage, VA, to a value greater than VBATT. Current circulates through L1 and D1 and ramps down to zero as L1’s stored energy decays. Values of 100 pF for C2 and 220 k_ for R2 set the astable oscillator’s frequency at approximately 20 to 30 kHz.
The principle of the operation in this circuit is when IC1’s output pulses high, Q2 turns on and saturates, sinking current, IL, through inductor L1. The inductor current ramps up at a rate determined mainly by VBATT; L1’s inductance; and Q2’s on-time, tON. During this interval, LED D1 and Q1’s base-emitter junction are reverse- biased. Provided that the inductor does not saturate, current IL ramps up linearly and reaches a peak value, IL(PEAK) at the end of the on-time. When IC1’s output goes low and Q2 turns off, L1 generates back EMF to forward-bias D1 and raises its anode voltage, VA, to a value greater than VBATT. Current circulates through L1 and D1 and ramps down to zero as L1’s stored energy decays. Values of 100 pF for C2 and 220 k_ for R2 set the astable oscillator’s frequency at approximately 20 to 30 kHz.
No comments:
Post a Comment