frequency to voltage converter

[crazy-igzp]

voltage-frequency converter ,monostable-based on logic gate !
can't find ! why it doesn't work ! help me finish it !

 

[Analog Ground]

One problem is R1 starts out holding the input of U5 low. Then, the high output of U5 causes the output of U4 to be low. The low output of U4 goes to the input of U1. With a low input on U1, nothing happens. The output of U1 cannot change with a low on an input of the NAND gate. In short, nothing can start.

 

[gehan_s]

Analog Ground is correct. Why do you need such a feedback anyway? I think you don't need U1:A and U4 either.

Regards

edit
ok maybe keep U4

 

[Analog Ground]

I think the idea is to make a one shot with an R1*C3 time constant. However, most designs of this type would use an edge triggered flip-flop with the input signal into the clock input and then feedback to an asynchronous clear input. I think implementing a design with just logic gates is more difficult. You probably end up implementing a flip-flop sort of circuit anyway.