No put back the components provided by the datasheet. Try "playing" with the 100K resistance between pin 2 and the 0.1uF capacitor. Lower this value, in order to achieve greater amplification of the incoming signal. Try it until a few Kohms.hossam abdo said:but i change the 20pF capacitors to 22 PF, also i putted resistance 240kohm instead of 300k.
are these affect the function of the circuit?
the same problem occurs when i use two mobile phones, but when i use one mobile phone with a land line phone , the operation achieved properly.
I do not know what is the problem?