In this video, we’re going to look at inductive sensors and Hall effect sensors. I’m going to be explaining what they do, how they do it, and also how to test them. So let’s start off with the inductive sensor. Now, what this sensor does is it can detect the presence of any metallic object. It doesn’t matter if it’s magnetic or non-magnetic, it will still pick it up. And how does it do this? Well, it’s quite simple. The DC current from your supply passes through an oscillator which converts it into an AC current. This AC current is then fed into some conductive claws at the end here, and what that does is it produces a changing magnetic field at the top.

So when you hover a metallic object over the sensor, it actually induces a current called eddy currents inside the conductor. The eddy currents produce their own magnetic field, which push back, causing a disturbance in the original magnetic field. This disturbance is sensed by the detection circuit inside the sensor, which triggers the output.

Now let’s talk about the Hall effect sensors. It looks very similar to the inductive sensors, but what this one does is it detects magnetic objects. Inside this sensor is a thin strip of conductive material often referred to as the Hall element. And this element is connected to a supply of current. When you pass a magnetic object close to the sensor, it will produce a voltage across the element. This voltage is actually quite small, so it goes through an amplifier and then a detection circuit which triggers the output.

These sensors have three wires, a brown, blue, and black wire. This is the industry standard for these sensors, and in some cases, you may even have an additional white wire making it a four wire sensor. As you can see from the label on this inductive sensor, we have a PNP type. So the way we connect it is as follows. The brown wire goes to the positive terminal of your supply. The blue wire goes to the negative terminal of your supply. The black wire is your output, so you connect your load across this black wire and the blue wire.

As you can see from the label on this Hall effect sensor, we actually have an NPN type sensor this type. So the connections are slightly different. The brown wire is connected to the positive terminal of your supply. The blue wire is connected to the negative terminal of your supply. The black wire is your output, so you connect your load across this black wire and the brown wire.

So here we have both sensors wired up and ready to go inside our prac box. One thing to note is to make sure you’re supplying the sensors with an appropriate voltage. These two sensors have a maximum rating of around 30 volts, but here we’ve got it supplied with 24 volts, which is fine. Our load is going to be these two LEDs. The green one is connected to the inductive sensor, whereas the red one is connected to the Hall effect sensor. So when either of them light up, we will know which sensors have triggered. We’re going to be testing out a bunch of different materials. Here we have a metal ruler, a piece of foam, small magnet, a pencil, a wrench, and a magnet I just took from a motor.

So as you can see with the metal ruler, the inductive sensor is triggered while the Hall effect sensor isn’t detecting it. The foam is not detected by either of them. The small magnet is detected by both of them. Now, one thing to note about the Hall effect sensor is that they are usually set up in a way where it will turn off in the presence of a north pole magnet. So this is actually a good way to identify which side is north and which is south. The pencil itself doesn’t get picked up by either of the sensors, but this metallic strip holding the pencil together with the rubber is picked up by the inductive sensor. This wrench is like the metal ruler. It was only picked up by the inductive sensor. And lastly, we have the motor magnet, which only gets picked up by the Hall effect sensor.

But what if we didn’t have an indication light to look at? How would we know if the sensor was actually working? In this prac box, we can’t see that light. So what can we do? Well, like we did before, we can attach our own LED to the output terminal. The other option is to measure the voltage. So as you can see here, we have us apply at 24 volts, and if we measure the voltage across this LED, we should get 24 volts as well. If we drop the voltage down to say, 12 volts, we should also get 12 volts across the load. And so that’s how you can test whether your sensor is working properly.

But one thing to note is that these sensors are rated to supply a maximum current of around 100 to 300 milliamps, so don’t expect it to be able to power something like a motor or a heated lamp. And that’s how an inductive and Hall effect sensor work. If you enjoyed the video, please make sure to like and subscribe down below. Thanks for watching.