Astable Multivibrator using 555 timer

Ok so I am back. I guess I don't have anything better to do in the world!The Astable multivibrator is stable in two states i.e the low and high and it keeps on oscillating between them with a specific time period determined by the values of resistors and capacitors used. Now we come towards the connections ... Pin  8 is Vcc so it's connected to positive terminal of battery .. here let me tell you that in almost  every IC the last one will be Vcc ... connect pin 1 to negative terminal of the battery and connect your output to pin 3 which can be anything either an LED or speaker.A resistor R1 we'll call it is connected between pin 4 and 7.Another resistor R2 is connected one leg to 7 and other to 2.Pin 6 is connected to 2 and 2 is grounded through capacitor C1.The discharge time is:
td=0.693*(R1+R2)*C1
Charging time is: tc=0.693*R2*C1
Time period is : T=td+tc
Frequency with which LED will flash is: f=1/T so by adjusting the values of resistors and capacitors you can make the circuit resonate at any frequency. The working principle behind this behavior is that when capacitor is being charged the LED flashes but as the capacitor is fully charged it behaves as open circuit and no current flows. A flip-flop which is part of the IC's internal circuitry comes into action and causes the capacitor to discharge through resistor R2 in this way a pulse train of required frequency is generated.
For a demo watch my video on Youtube!




























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Monostable configuration of 555 IC.

555 IC is a timer IC which can be operated in four modes: the astable,monostable,bistable and schmitt trigger(NOT Gate). Right now I'm going to talk about the monostable configuration. The reason it's called monstable is that it's stable in one state which is pretty much obvious and that state is "low", it's "high" state is short lived and dies down quickly.Now let me quickly describe the pins of the IC.Counting starts from the small dot. Pin 1 is ground, pin 2 is trigger, pin 3 is output, pin 4 is reset, pin 5 is control, pin 6 is threshold, pin 7 is discharge and pin 8 is Vcc where you plug in the positive terminal of your power supply. Now to get the circuit running, you connect the pin 1 to negative of power supply. Pin 2 is the trigger so we connect a switch there which is used to trigger the response, the other terminal of switch is connected to +ve of power.Pin 3 is the output where you'll observe the response.You can connect basically anything LED, speaker etc. Pin 4 is the reset. What happens is that when the capacitor gets charged it behaves as an open circuit and no current flows resulting in the stable "low" state. To generate another response,we press the reset button to discharge the capacitor. You connect the pin 5 to a 0.01 microF capacitor which is grounded. This pin is used just to regulate the power. Pin 6 is threshold , the capacitor in use C1 is connected across it and the other leg of capacitor is grounded, pin 6 is also connected to pin 7 and then a resistor R1 is connected to it which then connects to +ve of power supply.Pin 8 is Vcc so we connect it to the power supply or battery or watever you are using!The formula used to calculate the time period is :
                                                 T=1.1*R1*C1
The LED will flash momentarily and then it'll go blank until you decide to reset the process with the switch you installed!That's it ... Next up is the Astable Configuration.
























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