Lesson video

Hi, my name's Mr. Brown and welcome to today's design and technology lesson where we're gonna be thinking about integrating programmable systems into products.

We're gonna be thinking about how to keep safe with electrical components.

We're gonna be considering how to secure our electrical components within our products and how to complete them.

Right, without further ado, let's think about the learning outcome, the lesson cycles and keywords.

So today's learning outcome is to safely secure electrical components into designs.

Here are our keywords for today.

So the first one is push-to-make switch.

So this is something that controls a circuit by pushing the connection together.

Micro:bit pins are connections on the edge of the board, used to add offboard components.

Electrical wire, it's usually made from copper and covered with insulation to prevent electrical shock.

And safety measures, actions taken to prevent accidents when working with electricity.

We have two learning cycles today.

The first learning cycle is keeping safe with electrical components, and the last one is securing electrical components.

Of course, we're going to be starting today with keeping safe with electrical components.

Right, so when we are thinking about an electrical circuit for a museum alarm, it could contain a whole variety of different components, and this picture just has a few select components that you could actually have and that you might actually need.

There are many, many other different types as well.

You might want to explore and think about what they are and what you've chosen as your inputs and your outputs.

But these are just a selection.

Let's go through them.

So here we've got some electrical wires or crocodile clips.

The crocodile clips are on the left hand side and you can't really alter the size of them, unless we really wanted to.

It does affect them quite, it's a bit tricky.

Whereas the coils or electrical wire there, there's a coil of red, it's coil a black, they can actually be cut to the size that you want.

We have a micro:bit.

There's a wire stripper there.

We're gonna come onto that later in this lesson.

There's zinc-carbon cells in a battery pack and this battery pack feeds directly into the micro:bit.

There's some electrical tape.

You can get a variety of different colours of the electrical tape.

We just happen to have red and black here that goes alongside the electrical wires.

Same colours as the electrical wires.

There's a push-to-make switch.

There's two different types there.

So one's just got these split pins and the other is using the foil.

There's LEDs.

Now LEDs can come as singular LED lights or they can come as strips, which you can actually attach to the micro:bit.

We've got a bulb and a holder, and we've also got a three volt buzzer as well.

These are just some of the things that you could be using.

Right, quick check for understanding.

Which of these is less likely to be in an electrical circuit for a museum gallery alarm prototype? So which is less likely? They could all be used but which are more likely to be used in an alarm prototype? That's right, it's A.

Now that's a push-to-break switch and that turns components on and off, but it's less likely to be used in a museum alarm because it's less likely to be affected by someone trying to get too close to an artefact, for example.

Right, when the components are being connected to the battery pack, electricity flows through that circuit and so that makes the micro:bit and the components that are attached work.

But sometimes circuits are not connected properly, and this can mean that they can be quite dangerous.

So we have some safety measures, and we think really carefully about what sort of safety measures we can bring in.

So zinc-carbon cells are used in school instead of alkaline batteries and rechargeable because they are less likely to short circuit or get hot.

If the cells do look damaged, please tell your teacher.

Don't touch them.

Making sure that we keep water away from the circuits and from the cells.

We need to connect battery packs last when we are actually making the circuit together, and disconnect them first when we are finished.

And most importantly, always follow the teacher's instructions carefully.

Check for understanding, which of these is not good advice for keeping safe with electrical components? A, if the cells look damaged, tell the teacher and don't touch them.

B, keep water away from the circuit and the cells.

C, connect the battery packs first when making the circuit.

Which of these is not good advice for keeping safe with electrical components? That's right, it's C, connecting the battery packs first when making the circuit.

It might be that it won't be an issue, but as soon as we add battery packs and cells to a circuit, then what tends to happen, well, what happens is that the electricity is then starting to flow through the circuit.

If we make sure that we connect them last, then we have the less time possible for the electric circuit to be going, the electricity to be going around the circuit.

So let's think about some of the dangers of using cells and batteries.

So a short circuit is when a positive and negative terminal are connected to each other, and this can be really dangerous because they overheat.

It could be components such as the leads might actually melt, and dangerous fumes may come from the components as well.

Lastly, you could also get a burn.

What is the problem with this circuit? Have a look.

There is a light bulb and a battery.

What is wrong with this circuit? That's right, Jacob.

So both the electrical wires from the light bulb are connected to one side of the battery, and this can create a short circuit, and that's incredibly dangerous.

What's the problem with this circuit? Let's try and do some fault finding and see if we can understand what is wrong with this circuit.

That's right, one of the electrical wires doesn't connect to the light bulb, but there's still electricity flowing through it.

So we need to be very careful and very safe.

Here's your task A.

So first thing, discuss how to keep safe when using a micro:bit in an electric circuit.

So think about how you're gonna keep safe when we're using micro:bits and other electrical components.

Then I want you to write down a list of questions to ask when you're building these electrical circuits safely.

So what sorts of things do you need to ask yourself or other people? What I'd like you to do now is to think about the discussion, have a discussion with your partner and write down a list of questions.

Fill in in that table a list of questions that you need to always ask yourself when you're building an electrical circuit.

All right, off you go and I'll see you soon.

Okay, so Izzy and her group talked about safety measures when using a micro:bit in an electrical circuit, and they listed the hazards to look for when working with electrical circuits.

So here are some of the questions that they asked themselves.

Are the cells safe to use? Well, they're not hot, they're not leaking.

They look okay, I think we're all right.

Is the water nearby? Someone's got their water bottle out, we're just going to move that outta the way.

Are wires carrying electricity bare? Have you got bare wires? Well, maybe we need to think about how we can keep that safe, making sure that the insulation is around the wires.

Is the circuit connected properly? Is it working? Well, it's not working.

Let's disconnect it and just take one component at a time and think about how to keep safe.

Are the components connected correctly? It could be that the wires are loose, it could be a number of different things, but this is where we need to make sure that we're doing fault finding really carefully.

Right, good.

Well done.

So we've thought about how to keep safe, we've thought about all the different hazards, we've thought about how we can, all the different questions we need to ask ourselves when we are working with electrical circuits.

I think we're good to go.

Well done.

Okay, so we're now ready to move on to learning cycle two, that's securing electrical components where we're gonna use all those keeping safe rules, and we're going to apply them when we're securing electrical components.

So we're gonna talk about electrical wires firstly and actually thinking about electrical conductors within electrical wires.

So most electrical wires are made of electrical conductors, usually copper, and that allows the electricity to flow to the electrical components.

So the copper wire inside is the conductor, and this is what makes electrical components work.

It links the cells to the components carrying the electricity along the wire.

Now we've also got electrical insulators in the electrical wires.

Now they are covered, the electrical wires are usually covered in an electrical insulator, such as plastic.

A plastic covering, often PVC, to protect us from electricity flowing through the copper.

This actually stops us from getting electric shocks because whilst we want the electricity to flow through the copper, we also don't want to actually touch the copper wire when the electricity is flowing through it.

Now the coils of electrical wire that we spoke about earlier in the lesson we might use instead of crocodile clips.

Crocodile clips are really great just to get us going and making sure that everything is working.

But electrical wire can sometimes be better than crocodile clips for some projects.

It might be cheaper.

It might be easier to place into a product.

It can be more flexible in length and size, so you can actually determine how big you want it.

But it is tricky to prepare the electrical wires at both ends and attach them to the components.

Crocodile clips is really nice and easy 'cause you've got those wonderful crocodile clips at either end and that helps enormously when we're trying to connect them.

Bare electrical wire is a little bit more tricky, but we're gonna show you how you can do it.

And how we can do it is we first of all start using a wire stripper.

This is a picture of a wire stripper here and it can be used to cut electrical wire.

Now if you see that diagram, you can see that there is an area there that's got a slight blade where that actually cuts the electrical wire where you want it.

So let's say you want 10 centimetres, 20, 30, whatever it is, then you measure how much you want and you cut it using that part of the wire stripper.

But the wire strippers can also strip away the plastic insulation and that exposes the metal of the electrical wire, and this is what we use to connect the electrical components together.

And it's a really clever tool for stripping the wire away from the copper and exposing the copper, if it is copper, it usually is, the electrical conducting wire underneath.

It's a really clever thing, you put it in between the two teeth, pull the handles together, and then it just strips that insulation layer off.

It's really clever and we're gonna show you how that works.

Okay, check for understanding now.

Wire strippers can strip away plastic insulation from electrical wires and they can also A, fold electrical wire, B, twist electrical wire, C, can connect electrical wire, or D, cut electrical wire? What can wire strippers do as well as stripping away plastic insulation? Is it A, B, C or D? That's right.

Well done.

It's cut electrical wire.

And let's show you how the electrical wire is actually cut.

There you can see a GIF of the electrical wire being cut really safely as the handles are pulled together.

So the first thing to do is to measure the length that you want, and you might want to add a little bit extra for the ends where you're going to expose the wire.

You then place the electrical wire in the cutter, you squeeze the handle and then it cuts the electrical wire.

Very, very simple.

Now, if you didn't have some wire strippers like this, you can also use pliers.

A lot of different pliers have the same sort of ability to cut the electrical wire.

So you can do that if you actually, if you don't have any wire strippers.

But wire strippers are really effective for helping you with this.

So how do we strip the electrical wire? Well, as you can see there from the GIF, we'll go through this one by one.

So you measure how much you want to strip off.

You then place the electrical wire in the teeth of the wire stripper.

You then squeeze the handle and that takes off the insulation.

Now you can also do this with pliers, but it is quite tricky and quite often, certainly when I've been using the pliers instead of the electrical, the wire strippers, sometimes I do actually cut through the electrical wire because you have to be very, very careful.

It's a bit more tricky than using the wire strippers.

But it can still be done.

Okay, so we're now gonna talk about preparing the electrical wire.

Now once I've stripped some insulation off or once I've cut the piece that I want and I've stripped some, stripped the wire off both ends, I then twist the copper to form a neat electrical wire.

What you don't want is little strands of copper coming off.

So it's a really good idea to actually twist them on both ends, so it forms a neat electrical wire.

You then need to fold the component connector you are attaching it to.

So let's say for example the pins of a micro:bit, they've got a hole there.

So if you create like a hook from the twist from the copper, then you can hook it over the pin.

Now remember we don't add cells until the connection is secure, and that you've actually checked the circuit really carefully.

The only issue with this is that the ends of the electrical wire will still be bare and they'll still be exposed.

So when we do actually put electricity through, those ends will still have electricity going through, so we have to be really careful with that.

And a way of actually solving this issue is using electrical tape.

Now, electrical tape, which is also known as insulating tape, is an electrical insulator and that stops electricity from passing through it.

It's a really good thing to be using when we are trying to conceal bare wires, so that we know that there's no electrical current going through it.

Now it's made from plastic called polyvinyl chloride, PVC, and it can be used to cover electrical wires that might be exposed.

But also, not only can it do that, but it can also secure wires in place.

Let's talk about the wires that we're attaching to maybe some of the pins of the micro:bit.

They might fall off really, really easily.

So with a small tiny bit of electrical tape, I can actually secure them in place.

Check for understanding now.

Electrical insulating tape is usually made from, A, fabric, such as cotton, B, wood, such as MDF, C, plastic, such as PVC, or D, paper, such as cartridge paper? Is it A, B, C or D? That's right, it's C, it's made from plastic usually, something like PVC.

Well done.

Right, we're now gonna be thinking about securing the electrical components such as the battery pack to a micro:bit.

And there you can see on that picture, that battery pack does not have any cells in it at the moment.

Now battery packs for a micro:bit do not have exposed electrical wires when the cover is being put back on and the cells are in place.

They attach securely, but they're really tricky to remove again.

So what I would suggest is when you actually put these in, be really careful trying to remove them again if you need to.

You might not need to remove them, but if you do, they're very, very difficult to remove again and they can be pulled, if you pull them out too much, then you get the connector staying in the micro:bit and that can make things really difficult to use that battery pack yet again.

So be very, very careful if you have to remove it.

Now, the picture there really helps us to identify where the connection is.

So that's the connection from the battery pack into the micro:bit, and then also the battery pack for the micro:bit.

Jacob quite rightly says that cells can be added to the battery pack later.

So we're gonna now think about adding in external input components, so for example, a push-to-make switch.

Now, they can be added to the micro:bit pins using either electrical wire or crocodile clips.

And if you have a look at this picture here, you'll see that the micro:bit pins, we've actually used some electrical wire from those coils that we spoke about earlier in the lesson.

As you can see from the picture on the left, they are not attached by electrical tape or by anything else.

They are actually quite tricky and they will probably fall out.

So a small piece of electrical tape does actually keep the electrical wire in place.

So we're now gonna be thinking about other external components, this time output components, for example, a buzzer.

Now they can also be added to the pins using electrical wire or crocodile clips.

In this example, you can see that we've got electrical wire being added to the micro:bit pins.

So the wires from the buzzer have gone directly onto the pins.

And if you notice very carefully, you'll see that both the buzzer and the push-to-make switch are the black wires are connected to the ground button.

That's the one on the right hand side, the right hand hole, the right hand pin.

And the push-to-make switch is on pin zero, and the buzzer is on pin one.

Now, to make these really nice and secure, the electrical tape can keep these electrical wires in place.

And there you can see that you've got one wire going to the push-to-make switch, that's on the left on pin zero, and pin one is the thinner wire that goes straight to the buzzer.

So it's onto you now.

So it's your practical work.

You need to attach your electrical components into the museum gallery alarm, thinking about safety measures.

So, first of all, we should check that the correct HEX file has been downloaded.

We need to connect the battery pack safely, need to secure them safely.

So where are you actually going to put them into your museum? And then we need to connect any external components.

You might not be using any, but if you are going to connect them, you need to connect them nice and safely, perhaps using electrical tape.

Perhaps you want to actually make some, cut up some, cut and strip some electrical wire to help you, and then you need to check that it works.

So we've checked that the components and the micro:bits work and the HEX file works.

Now what you need to do is make sure that this works once you've installed it into your museum.

Right, good luck.

Hope it all goes well.

Remember if something doesn't work, just go through it logically and find the fault.

I'm sure you'll be doing a great job, and I look forward to giving you some feedback in a few minutes.

All right, off you go.

All right, welcome back.

Let's go through how, see how Jacob's been getting on.

So he thought about the safety measures he's gonna need and he made sure that the electrical components were safe to use.

So he went through, he checked that the right HEX file had been downloaded.

He connected the battery pack and the micro:bit together.

He secured them to the outside of the box, outside of the shoebox, sorry.

And then he connected the switch and the buzzer, and then he used the electrical tape to keep the electrical wires in place, and then he checked that the micro:bit worked.

Well done Jacob.

It worked.

Right, let's go through the key learning points from today's lesson.

So firstly, when we use electrical components, we need to follow rules to stay safe, and we talked about that in task A, and I'm sure you applied that in task B.

Wire strippers can create electrical wire that can be hidden within designs instead of using crocodile clips.

Remember, using electrical wire is a really good thing just to keep those wires hidden so that we don't have those wires exposed.

It's also often quite cheaper, quite a bit cheaper than actually using crocodile clips.

Alarm inputs, such as a push-to-make switch, they need to be placed near the artefact that they are protecting.

And the electrical components can be secured using electrical tape.

Those are our key learning points from today's lesson.

I'm sure you've done a fabulous job and you've all got your components safely secured into your museum, your shoebox museum, and I'm sure they're working perfectly.

So well done.

You've worked really hard today, worked really safely today, and I look forward to working with you next time.

Okay, goodbye.