modify FK408 to use a 3.5mm mic jack instead of a microphone sensor. How to? (851 views)
how would one modify the FK408 to use a 3.5mm mic jack instead of the default microphone sensor. I want to connect a 3.5mm headphone jack cable between my smartphone and the FK408 board so that when the phone plays noises through the mic jack it turns on some 12v led lights.
I have tried simply removing the microphone and replacing it with a 3.5mm headphone jack cable but it does not work. someone told me resistors needed to be changed, but I do not know much about circuit and need basic infomration to change the circuit.