LED Flasher
Category: Analog Circuits
Designer: RANA MUHAMMAD ADNAN KHALIL
Notes
This circuit is designed and simulated in Proteus 7.10. This is very interesting circuit of LED flasher, another name of this circuit is Bi-stable oscillator. The working of this circuit is given below. 1. In LED flasher circuit, the flashing frequency or time is depend on RC time constant i.e., product of C1 and (R2 + RV1) or C2 * (R1+RV1). 2. Change in capacitor value changes the frequency and also base current of transistor. 3. Increasing capacitor value decreases the frequency but increases the transistor base current. 4. While changing the resistor value only changes the frequency of the flashing LEDs by changing the charging time of capacitor. 5. Increasing resistor decreases frequency and decreasing resistor increases flashing frequency. 6. So first select capacitor according to base current, once you select the capacitor then select resistor according to flashing frequency (f = 1/T & T = R*C). 7. If you want to modify flashing frequency any time then place a variable resistor as shown in animation. Applications: 1. This circuit has many uses, one use is LED flasher. 2. LED flasher can be used for flashing side indicators for Auto-Vehicles (Bikes, Cars, Trucks, Buses etc). Download these files for performing more experiments.