Lesson video

Hello, my name's Mrs Finlay, and today, we're going to be learning about systems and new technologies.

Before we start, make sure you're somewhere quiet where you can hear my voice, and you've got some paper and a pen ready for today's lesson.

And for today's lesson, make sure you've got an exercise book or paper and a pen handy.

So let's look at what we're going to do today.

So we're going to start with the intro quiz, which you've probably done, and then we're going to recap on whether or not, you know your components.

So we're going to look at some of the components we use in circuits.

We're then going to look at different sensors and how they work.

And then we're going to use a specification to do some designing.

And as always, there will be an exit quiz.

Keywords.

Our first key word for today is a resistor.

Now this is an electrical component that restricts the flow of electricity in a circuit, and you can get lots of different types of resistors and there always the component that has the colour bands on them, and these allow you to quickly understand what the resistance is.

Let's look at the next key word.

Sensor.

This is a component that can monitor change in a circuit, and we're going to look at three of those today.

So let's see what the last key word is.

Thermistor.

Now this is a sensor that monitors change in temperature.

So the thermistor is a type of sensor.

It monitors change.

Let's have a recap on some of the electrical components that I think you already know.

Let's have a look together.

Okay, so LED, resistor, hmm, we just have that in our keywords, haven't we? Switch, and speaker.

So that's look at LED first.

Can you remember what an LED is? What do you think it does? And if you know what it does, do you know what it stands for? Let's have a look together.

It emits light.

An LED emits light.

Now it's a light-emitting diode.

So a light giving out.

Now what's diode mean? Diode is a type of component that only lets electricity through in one direction.

So LEDs, when you attach them to circuits, you have to make sure you put around the right way.

Otherwise they won't work.

Now resistor, can you remember what a resistor does? We talked about it in our key words.

Let's have a look.

It controls the flow of electricity, yeah, because it creates resistance.

Only so much current can flow through it at once.

What about switch? Think about a switch in your house, what does it do? Yeah, switches the flow of electricity on and off, okay? And finally, speaker.

What does a speaker do? Yeah, easy one, outputs noise.

Well done.

Okay, so we're going to look at how change happens with light levels.

So this is my little circuit and I've got my LED on here and I've got my battery pack.

Now I'm actually using a phototransistor which works slightly different than to a light-dependent resistor.

But that's fine, that's fine because it's the same kind of idea.

So here's my circuit and I'm going to cover my little component here.

And as I cover it, and see if I put it up to the screen, you can see that the light comes on.

And not only that, it's actually changing colour cause the LED I've got has the ability to change colour.

See if I can just keep my hand over there.

If I cover it like that, you can see the different colours changing.

And this is a time circuit as well.

So I could have the light, as soon as it's sensed, I could have the light just staying on for half an hour or something like that.

Can you think of a situation where you might want a light to come on for a set period of time? Yeah, maybe a child's nightlight when they're going to bed, or a security light.

So you might want to come on a fit, it gets stopped, and then it stays on for maybe half an hour and it switches off afterwards.

So these light-sensitive components can output to lots of other things as well.

It doesn't just have to be LEDs.

It might be motors that come on or something like that.

And this is how streetlights work as well.

They sense light being out.

Here's my little thermometer, that I have got my little thermometer circuit and you can see thermistor on the end there.

Okay, the right way, there.

Like a very flat pinhead.

And thermistors are used to monitor change in? Temperature, brilliant! And we've also got some other components on here.

So it's a good opportunity to test your knowledge.

So what about these ones down through here? If you can see those.

They got different colours going down through them.

that's a clue.

It was in today's keywords.

Yeah, resistors, well done.

And these are super easy because actually they're labelled.

That's right, they're LEDs.

And then we've got an IC chip in here.

Okay, little component, and it sits in.

It's sorted in its little housing there.

And then this is our power.

So I'm going to plug this in and I'm going to hope this works.

And what it's going to do is it's going to flash up to the different temperatures, and I've sorted this so it work inside.

So we'll pop it on.

There we go.

So there was a flash there.

Let's have another look, just wait.

Wait about 10 seconds and it should go again.

There we go, so it's going up to the third one, which if we have a look.

I've got it upside down.

There we go.

So it's going up to 18 degrees if it goes again.

Lovely, there we go.

So the thermistor is being used to gauge the temperature and we're outputting it through the LEDs.

So how.

Thank you.

So it's very visual and we can see it very easily.

Okay, so the last sensor we're going to look at is a pressure sensor, and this works on resistance.

So the more I squeeze this, the lower the resistance.

And you can do it on a scale.

So if I had an LED attached to this, it might become really bright at the start and then it fades and fades and fades.

They're not massively accurate but they will give you a state response rather than just another switch that goes on and off.

Okay? So this is an example.

I just want to show you what the component look like really.

This is an example of a pressure switch.

Okay, so the more I press, the harder I press, the lower the resistance.

So having looked at those three sensors together, let's just go through them again just to recap.

We have the thermistor which reacts to change in temperature, didn't we? So here we are.

There's my little thermistor that sat in here, and we had the LEDs outputting it to help me.

We had the phototransistor, or we could.

I was teaching you about the light-dependent resistor as well, but the phototransistor that was in here, and it sensed when there was a change in light levels.

And then finally, I talked to you about the pressure switch and how that can detect a change in pressure.

So having looked at those three sensors, let's have a look at this bathroom.

What I would like you to do is I'd like you to think about the three things that we were looking for.

So light, pressure, and temperature.

Have a look at this bathroom.

Where could we introduce sensors? So let's start with light.

Have a look at the different products that are in there, and which of those could you introduce a light sensor to? There might be a few that you've picked out.

You may want to pause the video and if not, you think you're super-confident, let's go with it and have a look.

So I chose the lights above the window and I've also chosen the lights in the actual bathroom which seemed to go above the mirrors as well.

So we could use, when it gets darker maybe, that those lights would come on.

Or we might have maybe something around the base where we put our hands and that covers it a little bit light of circuit we had and the light would come on for, I don't know, 20 minutes or so.

So we could introduce light sensors in those areas.

What about pressure? Where might we want to put a pressure sensor? Have a little look, see what you think.

Remember you can pause the video if you want to, but a quick little look.

Where do you think pressure sensors might go in? Let's have a little look together.

Okay, so I've got it on the tap.

So maybe you have a slight pressure sensor and it touches it and the tap goes on for, I don't know 10 seconds, 15 seconds.

And also stepping into the shower tray and on top of the toilet for the flush as well.

Now interestingly, can you think of an advantage of why having a sensor on the sink and the water runs for a certain amount of time? Why might that be an advantage? Yeah, that's right.

Because it might save on water.

So how many times do people put the tap on? Brushing their teeth is a great example.

Put the tap on, brush their teeth, you and I, still brushing the teeth, the water all the time is running.

Okay, or washing their hands, still washing their hands, water is still running, shaking off their hands, drying their hands.

They might have to then go back and put the tap on.

So having sensors and having products that run for a certain amount of time is going to often reduce the amount of water that's used or the energy that's being used.

Okay, so.

And that might be the same as the shower tray.

When you step inside, that's when the shower comes on.

Let's look at temperature then.

This might be a tricky one.

It might not be as many for temperature.

Can you find anywhere in there where we could fit a temperature switch? So have a little look.

Okay, so I'll show you what I got.

Let's have a look.

Yeah, I'll put a temperature switch on the taps but that would be more for the water, and again for the bath.

But you might have something within the bath that tells you if it's too hot or too cold.

What sort of user would need that, do you think? What sort of person having a bath would want to know if their bath was too hot or too cold? Yeah, that's right.

Maybe if you were running a bath for a baby or something like that and you wanted to check that it was within the right temperature.

You've probably come up with different answers and that's absolutely fine.

What I wanted you to do is to think about how we could use those sensors in the products.

So let's just recap on that in a little bit of a more clear way.

So if we used a light-dependent resistor for the bathroom light, we'd be able to turn the light on if it was dark.

And if we had a pressure switch on top of the toilet, this would flush the toilet when the bottom was pressed, but maybe not physically having to turn a handle as well.

So it's quite an interesting point to make.

Using a thermistor for the bath that could maybe light up an LED if the bath was too hot.

So if we think about our previous circuit that we had, anyway I've got it here, it might be that we use some color-changing LEDs, and it's red if it's too hot, it's yellow if it's okay, and if it's blue maybe, if it's too cold.

And then finally, we may have used a pressure switch for the shower.

And then that would turn the shower off when somebody is not standing in the shower tray.

And obviously the advantage for that is, you're not going to be wasting as much water.

So it's a benefit for the user.

What I would like you to do is design or if you want to, you could model or both, a toy for a dog on a walk.

And we're going to use this specification just as very gently get you to focus in one particular area.

So the product must help the user know where the dog is.

So how would they know that? How would they know where the dog is? So maybe if they're walking the dog at nighttime, what could we include to know where the dog is? So have a little think maybe.

You might want to use some LEDs or something like that.

The product must allow for the user to interact with the product.

So the dog's got to be able to interact with the toy and the owner's got to be able to interact with the toy.

So that's something to think about as well.

And then finally, it shouldn't be easily broken.

Okay, so if we thinking about a dog toy, think about the fact that dogs can be picking that up probably with its mouth.

We want to have it so that even if it was dark, we could see where the dog is.

We don't want it to be able to break.

And let's see if we can use some of those sensors that are in it.

You might even decide that, I don't know, you want a temperature sensor inside it.

So when it's inside the dog's mouth, it's a certain temperature and it glows, I don't know, use your imagination.

So you can choose.

You can either just sketch this out and loads of annotated notes, or you can model it as well or instead of, but I know your teacher would love to see your results and your ideas.

So let's review some of the work that we've done today.

A thermistor senses change in temperature.

Do you think that's true or false? A thermistor senses change in temperature.

What do you think? True luck.

It's true.

Can you think of an example where it might be used? That's right, yeah.

You could use it in a bath or you might use it in a heating system in a house.

Okay, let's do another one.

Changes in light would be detected by a light-emitting diode, LED.

Do you think that's true or false? Changes in light would be detected by light-emitting diode.

It's false.

An LED emits light, and light sensors are called LDRs, light dependent resistors.

I bet you knew that.

Okay, let's see one more.

A pressure sensor senses this change in temperature.

Is that true or false? A pressure sensor senses change in temperature.

What do you think? Yeah, it's false.

That's right, a pressure sensor, is change in pressure.

Well done today.

Make sure that you get your designs to your teacher 'cause I know they're going to be really excited to see them, and I'll see you soon.