Hi Audio and all,
I implemented your circuit,Audio...but I changed 330nF to 300nF,Used 100 nF and 5-35pF to 4-30pF.....I was unable to find LM2931A 5.0 .....I used 7805(Is it ok??).....I heard a whistling sound!!! That whistling sound spoiled all the voice which i was transmitting...just i got...