I am building a inertial chassis dynamometer for my electric RC car.
It's a pretty basic setup, a couple of drums mounted on bearings.
To measure the RPM of the drum I am using a simple coil mounted on the frame and a small disk magnet (pulled from an old headphone speaker) mounted on the end of the drum. As the drum "rolls" the magnet passes the coil and creates some current flow etc etc.
To measure the RPM, the coil is wired to a headphone plug that I insert into the microphone jack of my laptop. I then wrote some software (in VB using the winmm.dll WAVEINXXX functions) to "listen" to the input from the microphone jack and count the pulses.
**broken link removed**[/IMG]
This all works just fine. But I am curious to know why the signal I get for each pulse looks the way it does, specifically the portion highlighted in the green ovals in the attached pic. Even though this is working, I was wondering if there is some simple component addition I could make to clean this up.
Thoughts / Comments appreciated.
It's a pretty basic setup, a couple of drums mounted on bearings.
To measure the RPM of the drum I am using a simple coil mounted on the frame and a small disk magnet (pulled from an old headphone speaker) mounted on the end of the drum. As the drum "rolls" the magnet passes the coil and creates some current flow etc etc.
To measure the RPM, the coil is wired to a headphone plug that I insert into the microphone jack of my laptop. I then wrote some software (in VB using the winmm.dll WAVEINXXX functions) to "listen" to the input from the microphone jack and count the pulses.
**broken link removed**[/IMG]
This all works just fine. But I am curious to know why the signal I get for each pulse looks the way it does, specifically the portion highlighted in the green ovals in the attached pic. Even though this is working, I was wondering if there is some simple component addition I could make to clean this up.
Thoughts / Comments appreciated.