I had a look and now i m pretty clear as to how to connect the receiver circuit with the arduino. Coming back to the receiver circuit, i m nt getting a steady output. I have used two LM386 ICs, the first one giving a gain of 50 while the second giving a gain of 200. But the second goes into saturation. I donot know how can i achieve a constant output. Can i use AD620 ? or can u suggest me with some other alternative. Please help me out.