Low cost vehicle speed pickup

[Jester]

Magnetics is not my strong point. Can anyone recommend a low cost coil that could be used as a vehicle speed sensor pickup that would be located adjacent to a rotating drive shaft (I will epoxy a couple of small magnets to the driveshaft). I'm visualizing a coil about 1" diameter with a hole in the center for a mounting screw. The really old aftermarket cruise controls used this type of arrangement.

Preferable the coil would have pigtail connections to be connected to 10' of twisted pair.

Two most important factors: low-cost and easy to mount in a universal fashion.

Thanks,

 

[D.A.(Tony)Stewart]

Cost vs volume is unstated!

This Hall Sensor is easy to use $2 in volume. Any cable length per P.O.

http://www.hamlin.com/specsheets/55100 IssueAG.pdf

● Magnetically operated position sensor
● Digital, latching or programmable analogue
types available
● Medium, high or programmable sensitivities
● 3 wire (voltage output) or 2 wire (current
output) versions
● Reverse/Over voltage protection
● Built in temperature compensation
Benefits
● High switching speed up to 10kHz
● Long life; up to 20 billion operations
● Unaffected by harsh environments
● Operates in static or dynamic magnetic
field
● Customer selection of cable length and
connector type
BLOCK DIAGRAM
Notes:
1) Add capcitor Cn as shown, close to the sensor, for transient suppression if required.
2) Add resistor Rpu as shown for sinking output
Applications
● Position and limit sensing
● RPM measurement
● Flow metering
● Commutaion of brushless dc motors ● Angle sensing
● Magnetic encoders

 

[jiripolivka]

Magnetics is not my strong point. Can anyone recommend a low cost coil that could be used as a vehicle speed sensor pickup that would be located adjacent to a rotating drive shaft (I will epoxy a couple of small magnets to the driveshaft). I'm visualizing a coil about 1" diameter with a hole in the center for a mounting screw. The really old aftermarket cruise controls used this type of arrangement.

Preferable the coil would have pigtail connections to be connected to 10' of twisted pair.

Two most important factors: low-cost and easy to mount in a universal fashion.

Thanks,

Attaching a magnet to a rotating shaft is certainly possible but it adds a weight and may misbalance it. An easier way is to paint a white bar on it, and use a photosensor to generate pulses once (or more times) per revolution.

Reflective photosensors can be found on the market, or you can build one of a LED and a photodiode arranged so that the LED light gets to the photodiode only by reflection from the said white bar. Then simply use a counter to measure shaft RPM.