amplifying signal from crank position sensor

May 28, 2007 21 Replies

you don't need a floor jack

jack the vehicle up a little and support the transmission, lower it until the support it taking the weight, undo the mounts and then jack the vehicle up until you have enough clearance (this is more work, but will get the job done)

a typical CPS input looks something like this.

+----[R]-- 1/2Vcc | | |\\ --[R]--+-+--|+\\ | | \\ === | >---+--- | | / | --[R]--+-+--|-/ | | |/ | | | +-----[R]--+

the sensor puts out a higher voltage as the engine speeds up, the resistors on the left, and the capacitor form a low-pass filter which compensates for that.

the v0ltage needs to increase with rpm I'm not sure how high it needs to get though.

Bye. Jasen

Assuming the VRS has an inductance of about 100mH, 0.01uF gives a resonance at about 5KHz, and with a Q of >10 (actual value dependant on the input-R of the differential amplifier). The response is probably a little too peaky. The output will fall off rapidly at higher frequencies, and might give trouble at higher engine speeds. The response can be flattened with a 1k to 2k in series with the cap.

Tony Williams.

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