lm567

[ariakovo]

I want to detect if there is a 40KHz frequerncy.So I create a 40KHz frequency with a NE555 and then I put the output of 555 in the input of the 567.The out of the 555 is 5 Volt peak to peak +2.5 offset.I use a ceramic capacitor in the input of 567 (100nF).I use the two formulas to find the capacitors and the resistors and the circuit doesn't works.The output doesn't goes up when i put the frequecy.I have to say that i use a ceramic capacitor for the bandwidth of the filter in the 2 pin of 567.Can someone suggest values for ceramic capacitors and resistors for 40KHz because it doesn't works.Thanks in advance.

https://www.electro-tech-online.com/custompdfs/2008/03/LM567.pdf

 

[chemelec]

I want to detect if there is a 40KHz frequerncy.So I create a 40KHz frequency with a NE555 and then I put the output of 555 in the input of the 567.The out of the 555 is 5 Volt peak to peak +2.5 offset.I use a ceramic capacitor in the input of 567 (100nF).I use the two formulas to find the capacitors and the resistors and the circuit doesn't works.The output doesn't goes up when i put the frequecy.I have to say that i use a ceramic capacitor for the bandwidth of the filter in the 2 pin of 567.Can someone suggest values for ceramic capacitors and resistors for 40KHz because it doesn't works.Thanks in advance.

https://www.electro-tech-online.com/custompdfs/2008/03/LM567-1.pdf

It should work.
Can you post your exact schemetic, Or email it to me.
Include all your part values on it!

Gary

 

[k7elp60]

Acommon error people make with the 567 is not putting a pull-up resistor on pin 8(output). It is a open collector output.

 

[ariakovo]

It should work.
Can you post your exact schemetic, Or email it to me.
Include all your part values on it!
Gary

Hi i think that i find the problem.See the schem.I use in the place of R1 = 250hm: C1=100nF.I didn't put input signal capacitor and C3 and the whole thing worked.Also i put and a capacitor between GND and 8 pin because i see in the oscillocope a frequency 40KHz with on time 99% and of time 1%.After a BJT and it worked.I don't know why when i remove the C3 the circuit goes on.But it worked.Thanks anyway