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Help with time delay

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mngeow

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Hi,is there anyway to get time delay with a D Flip Flop?I've googled it and all I get is 555 timers or something.Got any ideas or suggestions?Thanks for your help! :)
 
Hi,is there anyway to get time delay with a D Flip Flop?I've googled it and all I get is 555 timers or something.Got any ideas or suggestions?Thanks for your help! :)

hi,
You can add a resistor from the Q output to the Reset pin and a capacitor from the Reset pin to 0V.

Choose say a 22K and a 10uF cap,I'm assuming that you are using a CMOS type ic.???

Tie the D pin high, pulsing the Clk line high will set the Q line high and it will time out as per the Res/Cap values.
 
hi,
This shows a delay, using a 22K and 4.7uF cap.
 

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  • AAesp02.gif
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I was about to post a drawing exactly same chematic as Eric, byt it also contains a schmittrigger between cap and reset. However I guess it should't be neccesary in order to get the circuit to work, only old habit :)

Aditonal comment:
You can also use a reset dominant SR flip flop instead of a D flipflop. Only backdraw then is that circuit can oscillate if input pulse has a longer time span then the delay of the circuit.
 
Last edited:
Thanks for the diagram.Is there a variable I must change (Eg. Resistor value) to get the time delay i want?Lets say if I want 5 sec time delay?:)

hi,
If you are using a CMOS type F/F you could increase the resistor to say 150K and the capacitor to 47uF, this is approx 5 seconds.

Just do a little experimentation to get the required time period.
 
Yo Eric I am trying to learn by doing LT SPICE.
I have it all drawn out BUT what is DVIEWS5 and where do I find it??
I get missing nodes error
then need to figure out what uic is??
 
Yo Eric I am trying to learn by doing LT SPICE.
I have it all drawn out BUT what is DVIEWS5 and where do I find it??
I get missing nodes error
then need to figure out what uic is??

hi deb
The DVIEW5 and DVIEW10 are located at the same link as before. LTspice yahoo user group

**broken link removed**
 
now I just need to find them?
I downloaded the cd4000 example and zip files
trying to make heads or tails of all the syntax (file types)
 
now I just need to find them?
I downloaded the cd4000 example and zip files
trying to make heads or tails of all the syntax (file types)

hi deb,
At bottom page from this link, get all the dview files.

**broken link removed**
 
Last edited:
How should I modify the circuit if like lets say I changing the pulse to a normal switch connected to VCC,when the switch is turned on,the LED will light up after 5seconds.Thanks.


hi,
Look at this circuit, OUT2 comes on 5 secs after the initial pulse.

Is this what you are asking.?

AAesp03.gif
 
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