Two wire Inductive Sensor

Thread Starter

wess.vic

Joined Dec 27, 2015
7
I started a project of my motorcycle that uses a toner ring and a two wire Inductive Sensor to eventually control a servo as the speedo gauge. My problem I'm having is I set up the sensor and toner ring on bench to scope the voltage produced. I'm new to using a scope and started with the rigol ds1050z. Im trying to scope the sensor at certain rpm with a specific air gap. I'm having trouble getting a clean sin wave. The voltage only amounts to 4mv at most. I would like some advice in implementing this type of sensor and scoping properly. I would really appreciate the help. Thanks
 

Thread Starter

wess.vic

Joined Dec 27, 2015
7
I started a project of my motorcycle that uses a toner ring and a two wire Inductive Sensor to eventually control a servo as the speedo gauge. My problem I'm having is I set up the sensor and toner ring on bench to scope the voltage produced. I'm new to using a scope and started with the rigol ds1050z. Im trying to scope the sensor at certain rpm with a specific air gap. I'm having trouble getting a clean sin wave. The voltage only amounts to 4mv at most. I would like some advice in implementing this type of sensor and scoping properly. I would really appreciate the help. Thanks
Also are two wire resistive inductive sensors best used with a current applied and just using that interruption of inductor to vary timing in circuit or using as it's own voltage producer?
 

Reloadron

Joined Jan 15, 2015
5,646
Depends on your sensor. A magnetic sensor is a coil wrapped around a small magnetic bar. I have one laying here which I believe was a crank sensor on one of my old trucks. With a gap of 0.250" it put out an AC voltage sine wave and i can't recall the amplitude but want to say 5 ~ 7 VAC. See if your center pin is a magnet, if yes and it's a magnetic two wire sensor then no external excitation should be needed.

Ron
 

Thread Starter

wess.vic

Joined Dec 27, 2015
7
Depends on your sensor. A magnetic sensor is a coil wrapped around a small magnetic bar. I have one laying here which I believe was a crank sensor on one of my old trucks. With a gap of 0.250" it put out an AC voltage sine wave and i can't recall the amplitude but want to say 5 ~ 7 VAC. See if your center pin is a magnet, if yes and it's a magnetic two wire sensor then no external excitation should be needed.

Ron
Thanks for the reply Ron
My sensor has no magnet sticking out but when I get near it with a ferrous metal or another magnet I can feel the pulling and pushing. If that helps what kind of sensor I'm dealing with. Thanks again
 

MrAl

Joined Jun 17, 2014
7,803
I started a project of my motorcycle that uses a toner ring and a two wire Inductive Sensor to eventually control a servo as the speedo gauge. My problem I'm having is I set up the sensor and toner ring on bench to scope the voltage produced. I'm new to using a scope and started with the rigol ds1050z. Im trying to scope the sensor at certain rpm with a specific air gap. I'm having trouble getting a clean sin wave. The voltage only amounts to 4mv at most. I would like some advice in implementing this type of sensor and scoping properly. I would really appreciate the help. Thanks
The output depends on a number of things like the number of turns and the magnetic biasing being used and the length of the air gap and possibly the speed of rotation. But i am wondering why you expect a sine wave output not all of them do that some output a pulsed wave.
The output should be more like a current i would think. That means if you connect a larger resistance to the coil you should see a larger voltage. You may have to amplify the voltage with an op amp.
The scope probe and ground lead should go across the coil leads with some kind of load resistance too.
 

Reloadron

Joined Jan 15, 2015
5,646
Thanks for the reply Ron
My sensor has no magnet sticking out but when I get near it with a ferrous metal or another magnet I can feel the pulling and pushing. If that helps what kind of sensor I'm dealing with. Thanks again
Based on that it sounds like a magnetic sensor so should not require any excitation. Should output a sine or square wave, the one I have is a sine and set about 1/4" off the teeth.The tach signal on my 92 Harley Electra Glide originates with the ignition timing module.

Ron
 

Alec_t

Joined Sep 17, 2013
11,639
My sensor has no magnet sticking out but when I get near it with a ferrous metal or another magnet I can feel the pulling and pushing.
That indicates the sensor includes a magnet, so you don't need an external one. Presumably your tone ring is ferromagnetic?
I'm surprised you get only 4mV output. Usually those inductive sensors kick out a Volt or more at shaft idling speed. They don't need an external voltage or current source (unlike a Hall-effect sensor).
 

MaxHeadRoom

Joined Jul 18, 2013
21,403
The voltage only amounts to 4mv at most. I would like some advice in implementing this type of sensor and scoping properly. I would really appreciate the help. Thanks
Some type of proximity switches require a pull up resistor as they are open collector format, this may be the case?
If you require a simple pulse detect then there are many proximity detectors that just detect a ferrous flag, no magnet required.
Oops I see this is a two wire, these often use the two signal lines for power and the signal simultaneously.
These are commonly seen on piston position detectors for pneumatic cylinders.
Max.
 

Thread Starter

wess.vic

Joined Dec 27, 2015
7
Thanks for all the replies much appreciated. I ended up getting another sensor with an external magnet that had a stronger field. I got a much stronger and visual reading that was clean. Thanks again will post my progress to those interested
 
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