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I'm having a problem in 555 astable mode...
Actually I'm using 555 to generate 5 frequencies so I'm putting a switch after R2 resistor keeping R1 fixed and C=1uF..
I know when it is open output it should be high and when closed output it should be low...
But it is not giving the correct output...why???

See the circuit above...when I close the switch the MULTIMETER reading should be 0V and when I release the switch reading shold be Vcc(9v)...
But it doesn't happen when you continuously switch on and off the switch....
I mean when I open the switch reading is still 0v it should be Vcc(9v)

Actually my aim is to blink the LEDs when I close the switch and turn off the LEDs when I open the switch but what happens is when I close and open the switch continuously, LEDs are blinking all the time in spite of having opened the switch.

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Having a high on the output of U1 at pin 3 will cause the rest of your circuits to oscillate and blink the leds.  This pin must go low to stop the rest of your circuit.

What I would do is to relocate the switch to pin 4.  Connect your switch so that in one position U1 gets Vcc and in the other position U1 gets ground.  This seems to me to be the similist solution.  Let me know if it works out for you.

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