Update:
i got the knock kit from jaycar, but the frequency band is wrong, it detects noise within 4.8Khz to 6.4Khz, which is too low, i am looking for a band of about 6.5Khz to 9Khz, so in order to achieve this i need to change a couple resistors. the one you change are the 2.7K resistor (inbetween the two 5.6K resistors top right of board) and i changed it to a 1.6K resistor to beef up the low pass filter, the other one you change is the 10K resistor (inbetween two 6.8nF caps top middle of board) and i changed it to a 12K resistor.
Now i havnt confirmed these changes but they should be pretty close