# Time Delay Circuit

Discussion in 'General Electronics Discussion' started by mngeow, Jan 13, 2010.

1. ### mngeow

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0
Jan 13, 2010
Hi guys,is there anyway to get time delay with D Flip Flops?For my project my school does not allow me to use a 555 IC,this is their way of challenging us I suppose?Haha.Anyway if possible give me a diagram of some sort that I could follow.Thanks for your help!

2. ### alex88

8
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Jan 20, 2010
How long you want to get for delay? if not long(less than 2^8 clock time), 8 counter will be enough for you.

3. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,505
2,853
Jan 21, 2010
Have a look at what you can do with schmitt triggers.

http://www.fairchildsemi.com/an/AN/AN-140.pdf

The hex Schmitt trigger is so versatile I sometimes wonder why they bothered to make any other logic at all :-D

1 Schmitt trigger can do much that you might want a 555 to do, and there are 6 in the package!

4. ### andreapg

11
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Jan 29, 2010
When the start button switch in open, pin 2 is on the high level; pin 6 is on the low level, because discharge switch (pin 7) is closed to the ground.
When I press the button, pin 2 goes to the low level, than the output (pin 3) will be energized. Discharge switch is now open, but pin 6 is closed to the ground by the capacitor, so it is on the low level.
When the capacitor is full charged, pin 6 goes to the high level, than the output goes to the start condition.

11
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Jan 29, 2010

11
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Jan 29, 2010
7. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,505
2,853
Jan 21, 2010
andreapg, note the above quote

8. ### andreapg

11
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Jan 29, 2010
Thank you. I didn' t know the meaning of "allow", so I didn' t understand the real problem...