DIY Audio Knock Sensor – How To
2 min read
It is possible to listen engine knock by connecting a 3.5mm headphone jack to a knock sensor and running it to the mic input on a laptop. This guide details the whole process. Knock sensor with 3.5mm male jack is available as an optional extra to the KSC3 engine knock sensor ECU.
Parts Needed
3.5mm Stereo Jack (Male) – Cut the end off a stereo mic or some old headphones (or source a bare jack from an electrical supplier).
3.5mm Female-Male, Stereo Extension Cable (3-5 meters) – Run cable from knock sensor to laptop inside the vehicle
Knock Sensor
Knock Sensor Pigtail (or buy a connector kit to make your own)
Headphones
Laptop
VLC Player – To listen to mic input in close to realtime. Latency will depend on laptop.
APO Equaliser – Filter out mic frequencies not in our knock frequency window
How To
Connect the 3.5mm male stereo jack to the knock sensor
Install knock sensor on engine, on engine block or cylinder head.
With all the parts connected (knock sensor, mic input, headphones).
Install VLC Player. Select Capture in VLC media player, choose the relevant inputs and outputs. Press Play.
Install APO Equaliser. Open APO Equaliser. Create window for mic input (knock sensor signal). Reduce volume of all frequencies outside of knock frequency window.
You should now be listening to the knock sensor signal in your headphones (there may be some delay/latency between the sound and hearing it).
Demo
This video is a demonstration of what is achievable with this audio knock listening setup.
