Need a little help with my circuit

  • Thread starter Ali Inam
  • Start date
  • #1
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Hi guys, today I made this simple form of door bell. It is working perfectly, there is a simple push button, which on pushing, enables the buzzer to buzz on sufficient voltage.

But, when I showed my circuit to my intructer, he asked me to modify it in such a way so that when I push the button, it should wait for 2 to 3 seconds before it buzzes.


Any idea how I may do it ? Any new IC to be implemented ? or should I change the values of the capacitors which I am using in my circuit ???

I changed the resistor values using the formula which is demostrated on the wikipedia portion of the 555 IC, but it was of no use.

Please help....


http://4.bp.blogspot.com/_RpOfkmvmO...h_jjP8N0/s400/simple+electronic+door+bell.JPG
 

Answers and Replies

  • #2
berkeman
Mentor
59,668
9,822
Hi guys, today I made this simple form of door bell. It is working perfectly, there is a simple push button, which on pushing, enables the buzzer to buzz on sufficient voltage.

But, when I showed my circuit to my intructer, he asked me to modify it in such a way so that when I push the button, it should wait for 2 to 3 seconds before it buzzes.


Any idea how I may do it ? Any new IC to be implemented ? or should I change the values of the capacitors which I am using in my circuit ???

I changed the resistor values using the formula which is demostrated on the wikipedia portion of the 555 IC, but it was of no use.

Please help....


http://4.bp.blogspot.com/_RpOfkmvmO...h_jjP8N0/s400/simple+electronic+door+bell.JPG

This is for school, so we are not going to give you a solution. However, we can give you hints...

What other functions can a 555 IC perform, other than just oscillator? If you added a 2nd 555 IC, could you use it to make a delay before enabling the buzzer oscillator?
 
  • #3
863
4
Essentially what he is asking you to do is operate the NE555 IC in what is called monostable mode - basically it only starts 'timing' when it gets a certain input signal. The wikipedia article is fairly helpful:

http://en.wikipedia.org/wiki/555_timer_IC#Monostable_mode

Basically, set your R and C to the correct time amount: 2 seconds is a long time and may require a pretty huge capacitor.
 
  • #4
99
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So you mean that I will have to use the formula which is available on wikipedia

t = RC ln (3) ??


and from this, I will try to get t=2 by changing the values of the resistors and the capacitors ?
 
  • #5
99
0
And berkemen, you mean that if I connect another IC with my circuit then it will be able to develop a sort of delay in its functioning ?
 

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