Changing frequency with 74HC14.

[ikelectro]

BTW: I don't understand how you getting such a high frequency output with a 0.1uF cap and those pot values. It should be a factor of 10 less than that. Are the component values changed?

ops sorry, My mistake. I used a 47pF by mistake!!!!

 

[ccurtis]

ops sorry, My mistake. I used a 47pF by mistake!!!!

Whoa, 47pF. That's okay. But, that would get the frequency onto the MHz. Now I'm really confused.

 

[ikelectro]

Whoa, 47pF. That's okay. But, that would get the frequency onto the MHz. Now I'm really confused.

now you can slap on my face!!!!!!!!!!!!!!!!!!!!!!!!!!1
again i made a mistake (now this time a writing mistake) ........
I have used a cap 22 nF (222 code)...!!!!!!!!!!!
extremely sorry to make you confused.... really sorry..........

 

[ikelectro]

I have used 47 pF in my another circuit, so I just mixed up it with 74HC14 freq circuit!!!!!!!!!!!!!!!!!!!

 

[ccurtis]

Ah, now I get it. Thanks for clearing that up.

 

[ikelectro]

You can get independent frequency and mark-space control with a four-gate circuit. Mark-space ratio is adjustable ~ 8% to 92%. If I can attach the schematic successfully it's here:
View attachment 69848

Edit: I used a CD40106 because of its symmetrical Schmitt threshold values. You could use a 74HC14 instead, but you might have to tinker with R1 and R4 values to allow for threshold asymmetry.

I just done it on the bread board but the frequency always fluctuate a lot.....
and i do it with 74HC14...

 

[alec_t]

1) How much is "a lot" ?
2) Does your circuit have supply decoupling capacitors?
3) If your 3V supply is a battery is it a fresh battery and not overloaded by other circuits?
4) What values are you using for R1 and R4?