LED Flasher Circuit


Posted on Feb 7, 2014

The 555 timer chip is a very versatile IC, because when connected correctly, it can it can create pulses of current at specific time intervals decided by the resistor-capacitor (RC) network. When a 555 timer creates pulses in this way, the LED doesn`t stay constantly on. It only turns on at a pulse and then shuts off after the pulse has passed. An


LED Flasher Circuit
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d it does this in a never-ending cycle, which creates the flashes of light. To make the 555 timer chip create pulses, it must be placed in astable mode. Astable mode simply means that the 555 timer has no stable state. It switches constantly between high and low, or on and off. This is why this mode is also called oscillator mode, because it uses the 555 timer an oscillator, which creates square wave signals. For this circuit, you will need several jumper wires because to connect all the resistors and capacitors to the 555 timer chip does become complicated. To simply the breadboarding of this circuit, jumper wires help to space out the circuit so that everything isn`t jumbled on top of each other. Again, the output of a 555 timer are square waves. There are 3 important time measurements for a square wave. There is the total length of the square wave (the time it is on and off or high and low), there is the length of time it is high (T. The amount of time that the square wave is high is its duty cycle. So, for example, if the total time of a square wave is 1 second and it`s high for 0. 2s, it has a duty cycle of 20%, because it`s on for only 20% of the cycle. The duty cycle is very important for an application like this LED flasher circuit. The duty cycle we choose determines how long the LED will stay on for compared to how long it is off for. Again, as an example, if we set our duty cycle to be 20%, this means the LED...




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