At the very least, you need to add a resistor between pin 3 of IC1 and ground to supply its input bias current. Try 1K. The blogspot article doesn't allow for Vin being capacitively coupled.
At the very least, you need to add a resistor between pin 3 of IC1 and ground to supply its input bias current. Try 1K. The blogspot article doesn't allow for Vin being capacitively coupled.