Oscillator 35khz with ic

[processor]

hi
i need a circut for genaration 35khz square puls
and i try to make with 555 but changed ferequancy in long time
please give me a idea

i liked make with 555 but increase and not fixed for ever

 

[crutschow]

What value of frequency stability do you need? What's the maximum low and high frequency around 35kHz you can tolerate?

 

[processor]

maximum high change 100hz
my circut increase 1hz in 2 second , very bad in 1day

 

[chuckey]

is your C2 a high stability component - do not use ceramic!! Like wise the resistor chain must be high quality components especially the variable device. Have you logged the frequency drift with the temperature?, you could try thermal cycling it to expedite any burning in processes.
Frank

 

[processor]

i need a way for fixed the frequancy
can use feedback with 555 that input changed with output
i searching for feedback
555 is better or micro avr?!!

 

[chuckey]

have you used a high stability type for C2? Any oscillator is only as good as its frequency determining components.
Frank

 

[crutschow]

You could use a crystal clock and divide the frequency with a digital counter to get 35kHz. For example a standard 3.64MHz crystal oscillator can be divided by 104 using two 4-bit programmable counter chips to get 35kHz, which will be accurate to within the accuracy and stability of the crystal you obtain.