As shown in the diagram below timer 555 works in astable
mode along with the internal circuit described in the block. There are
three resistors named R inside it and all have equal values.
Description:
Pin 2 of the 555 is the trigger input. If the voltage at pin 2 is<1/3 of Vcc, the flip flop switch to a low state of the output of the lower comparator. The output stage has an inverting action. In other words, output at 555 high when flip-flop output is low.
Now imagine if the power supply is first connected to the astable circuit. Timing capacitor is discharged at the starting. The output in 555 is high and voltage is 0V at pin2. With the help of resistor R1 and R2 and capacitor C starts charging. Note that C is also connected to pin 6, which is the threshold input of 555 timer.
Get remaining detailed explanation about the working of 555 Timer as an Astable Multivibrator in ElectronicsHub.Org site.
Circuit Diagram of 555 Timer in Astable Multivibrator Mode:
Figure 1 555 Timer as an Astable Multivibrator – Circuit Diagram
Pin 2 of the 555 is the trigger input. If the voltage at pin 2 is<1/3 of Vcc, the flip flop switch to a low state of the output of the lower comparator. The output stage has an inverting action. In other words, output at 555 high when flip-flop output is low.
Now imagine if the power supply is first connected to the astable circuit. Timing capacitor is discharged at the starting. The output in 555 is high and voltage is 0V at pin2. With the help of resistor R1 and R2 and capacitor C starts charging. Note that C is also connected to pin 6, which is the threshold input of 555 timer.
Get remaining detailed explanation about the working of 555 Timer as an Astable Multivibrator in ElectronicsHub.Org site.
