I am wanting to measure wheel speed on a vehicle. Each axle has a variable reluctance sensor. I am sharing this signal with the ECM. I am using a LM-2902-Q1. The data sheet is attached along with a schematic and output from the circuitry.
The rear axle output is really nice. As soon as the sensor voltage is positive, the output goes high to 5v and stays there until the sensor voltage is negative. Then the output goes to 0V.
The front axle isn't right. I drew up the scope data on AutoCad so it isn't exact, mainly to give you an idea as to what is happening. The yellow trace is the output of the circuit. The white is the output of the sensor. As you will notice, the output starts off right, but goes to 0V when it should stay high.
Any ideas?
Thanks in advance
Toby
The rear axle output is really nice. As soon as the sensor voltage is positive, the output goes high to 5v and stays there until the sensor voltage is negative. Then the output goes to 0V.
The front axle isn't right. I drew up the scope data on AutoCad so it isn't exact, mainly to give you an idea as to what is happening. The yellow trace is the output of the circuit. The white is the output of the sensor. As you will notice, the output starts off right, but goes to 0V when it should stay high.
Any ideas?
Thanks in advance
Toby
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