About Positive and negative edge triggering

[qwertyqwq]

Hi all. I want to make a positive and negative edge trigger circuit. May you guys help me...
First of all the goal is to trigger clock pin of a d flip flop (cd4013). The project is just about to learn something interesting.
Incıming signal is variable square wave %50 duty cycled. I want to generate a clock signal from that square wave. Every changing edges (rising & falling) the circuit will generate a pulse for clock pin of the flip flop. It will not change by input frequency. By the way bedore i wrote here , i also tried to do some but it wasnt desired one. The scheme is here ;

This circuit is working on high freq about 200hz-25 khz. But on less is not working well. I have also changed caps and resistor different type of values but the result didnt changed. In theory it was working. And also tried with ltspice. All things working as i desired. But in pratic ...
Some of the websites also mentioned sometihng like that;

But this time in simulation softwares the time width is too small then i wanted to generate.
So i thought you guys may help me about that. If you have any spesific diagram for that , i can take it gladly

Edit: The reason why im not using D Latch is all i want to do generate edge trigger.

 

[ronsimpson]

I have used the XOR circuit many times. Some times to get a 2X frequency out.

 

[Tony Stewart]

perhaps your trigger problems are due to logic family impedance. Rather than slow 4xxx series (assumption) Use 74ALC' or 74HC' series The pulse width can be very short <20ns which limits your maximum frequency but has no effect on minimum frequency when going into an edge trigger circuit.

 

[qwertyqwq]

perhaps your trigger problems are due to logic family impedance. Rather than slow 4xxx series (assumption) Use 74ALC' or 74HC' series The pulse width can be very short <20ns which limits your maximum frequency but has no effect on minimum frequency when going into an edge trigger circuit.

Hi steward thanks for reply all.
I dont think the reason about slow cd4013. Cause when i look at output of the XOR gate with scope , some of edge signals are missing. Sometimes it can detect edge espesially at high frequency , but sometimes not at lower frequemcy that i mentioned before.
Thanks.
Edit: xor gate is 74hc series.

 

[rjenkinsgb]

What are you feeding the XOR gate circuit with?

That must be a logic level signal with a fast edge for the R-C delay to function properly.
If it's a slow signal you could feed it through a schmitt gate such as a 4093 or 40106?

 

[qwertyqwq]

Thanks
Actually yes i though that before so you are right the signal is rising and falling slowly. After i saw that i put a buffer after it. The buffer is Nxp’s HEF4050bp. Now it looks like sharo enough. What do you think ? Should i change the buffer against two 74hc14 schmitts cause i dont have 4093 or 40106 ics .

 

[eTech]

Hi all. I want to make a positive and negative edge trigger circuit. May you guys help me...
First of all the goal is to trigger clock pin of a d flip flop (cd4013). The project is just about to learn something interesting.
Incıming signal is variable square wave %50 duty cycled. I want to generate a clock signal from that square wave. Every changing edges (rising & falling) the circuit will generate a pulse for clock pin of the flip flop. It will not change by input frequency. By the way bedore i wrote here , i also tried to do some but it wasnt desired one. The scheme is here ;
View attachment 123013
This circuit is working on high freq about 200hz-25 khz. But on less is not working well. I have also changed caps and resistor different type of values but the result didnt changed. In theory it was working. And also tried with ltspice. All things working as i desired. But in pratic ...
Some of the websites also mentioned sometihng like that;View attachment 123014
View attachment 123015
But this time in simulation softwares the time width is too small then i wanted to generate.
So i thought you guys may help me about that. If you have any spesific diagram for that , i can take it gladly

Edit: The reason why im not using D Latch is all i want to do generate edge trigger.

hello,

if your using your custom edge trigger circuit to clock a CD4013, it won’t clock on a negative edge. The CD4013 clock input has a built-in positive edge trigger. So it will only clock on a positive edge.

eT

 

[rjenkinsgb]

One or two sections of an HC14 would work fine.