# A simple guide to electronic components.

This video is just the basics of electronic components, what they look like and what they actually do – and how they work in fact So let’s start with one of the most common, the one that I just picked up there the resistor So this is a one thousand Ohm resistor I can tell that from the color bands on it, and we’ll look at that later on how the color bands are interpreted However the function of a resistor if I use the water analogy because the water analogy is very good If you have a pipe With water flowing through it and part of that pipe is narrowed down to a section Then that will restrict the flow of water through that pipe Say for instance the main water pipe coming into the house. If you put a very thin Pipe in line with that, even a fairly short one then it would really Restrict the flow of water coming in because the water would want to flow through quite quickly But it would be forced in through this narrow channel and the resistance Posed by that narrow channel would limit the water flow in the same way that a resistor Does exactly the same to electricity it limits the flow of electricity? the flow of Current and In this case with the water analogy the pressure of the water equals the voltage and it’s quite interesting that the chinese sometimes refer to the voltage as pressure and it is that’s exactly what it is and the flow of the water equals the current So the higher the flow the higher the current Now the construction of a resistor is usually in the case of these ones this is a carbon film resistor and You get metal film, Carbon film, wire wound but one of the most common is just carbon film or the metal film and they have a little ceramic Tube which is coated with either the metallized coating or a carbon coating up to a Specific thickness and the thicker the carbon coating on it and the the type of the composition they’re putting on it the more conductive it will be but then they can fine-tune that they actually cut a spiral round it and that creates a long thin path of the carbon and That increases the value of the resistance and once they’ve done that they put a metal cap in the end with the leads coming off and they dip it in a sort of I suppose it’s a lacquer really and Typically with the carbon film resistors which are my favourite, they’re one of the easiest to read it’ll be this sort of beige coloured I’m not sure. What would you call that color? I’ve never really thought about that Beige let’s call it beige it’s sort of rich beige and the metal film Resistors, which I don’t like because they’re usually blue and they’re really hard to read. The blue color makes the color bands It’s very…. it makes it easy to mix colors like orange and brown because they’ve got such a dark background But I’ll go into those colors afterwards, so that’s the function of a resistor I’m not going to go into too much at the moment because at the end of the video I’ll cover things like ohm’s law, but I don’t want to bore the pants off you so let’s move on to capacitors Oh – I should I should continue and say about the resistors the function of resistor is To limit the current flow so say for instance you had An led you wanted an led to light from a battery if you connected the led straight across the battery it would burn the led out in most instances but if you put a resistor in series with the let’s just draw as a physical Led and you hook across the plus 12 volts and zero Volts Then by choosing the resistor value you can actually limit the current to the correct value of the led they’re also used for things like time delays you might have a Resistor charging up a capacitor you know it trickles the current into it until the voltage reaches a certain level and then that could be used as a timing function, and you also get variable resistors where effectively it’s a Carbon track Connected at both ends are only really you only need to use a connector one end and with a wiper that actually wipes around that track so you know depending on its position that will vary the resistance, so Let’s move on to capacitor now Because they’re quite interesting so a capacitor in its most basic form is a layer of insulating material with a conductive surface on each side and The best way to describe a capacitor in the water flow theory is a chamber with a diaphragm in it that stops the water flowing directly through and That diaphragm can flex a certain amount in either direction So say for instance, you’ve connected it across a battery

The positive charge would flow in at this side, and it would cause it to flex over to the negative side It doesn’t actually physically work like this but this is a good way to describe it and if you reverse the polarity then that charge that amount that filled up would then be pushed out the other side and it would flex the other way and this allows capacitors to be used to basically hold a charge of electricity or in the case of the AC capacitors that you often see me using these in my led lamps that diaphragm it means that on the AC on each half wave when the polarity swaps that will let through a small amount of energy the electrons will flow back and forth through it, but not just pass right through like a short circuit So to describe a capacitor to actually show you what a capacitor does let’s make one. So I’ve got a bit of a cardboard here. This is a standard six by four photo a piece of photo material and I’ve got two bits of metalized films, so let’s say stick the metalized film on either side, so We’ve got a metal electrode, and I’m sticking it onto the insulator the dielectric and This is old aluminium tape I think that don’t seem to stick very well But that’s alright. It will do what we need to do and Then the other side of this I’ll stick the other bit of tape, and that’s the other electrode and This is the physical construction. That’s used throughout all capacitors They’re all pretty much like this, but not using cardboard and aluminium foil So let’s get that pretty much as close to the other one alignment as possible and the actual the two factors determine the capacitance here are the area of metallization that’s in parallel with other one and How thick the insulator is is in between them you think you know this cards. It’s you know it’s very thin so it’s going to be quite a You know it’s going to be a Modestly high-value capacitance, but that’s not true This is not going to be a high value of capacitance at all so let’s put this round let’s be optimistic and say 200 Nano Farad and I’ll connect it one side and the other side and The capacitance is actually… Oops! I’m not making contact I’m connecting on to the adhesive side here my capacitor measures One point. Oh that’s terrible isn’t it it’s one point eight Nano farad. It’s not very high at all and if I was to cut this in half, so the actual to prove that the area of the foil affects the capacitance if I get a pair of scissors Scissors, and I cut this in half right now So it’s one point eight three if I cut that in half It’s halved the capacitance. It’s now point eight, and if I cut that again in half, it’ll go down to about point four Which it has so that’s basically how the capacitor works. It’s basically an insulator the two metal plates on either side and the area of the metallization and the thinness of the separator is what Determines the capacitance and to get the value of capacitance up the it means that in reality for components like this little hundred keep in mind that I managed what was that just a couple of nano farad this one is rated 100 Nano farad and If you look at things like this one this is an electrolytic capacitor which is rated 470 Micro Farad, which is a massive capacitance and to achieve that … let’s get the notepad back in again To achieve the higher capacitance they often make the capacitors multi-layer, so this is something I just printed out, I designed on the computer as a printed circuit board design sort of layout But I just did it as a sort of graphic and if you can imagine that the blue is layers of insulation in the ceramic capacitors and these are metallized sort of plates then by alternating the pole sort of creating a comb of them with insulators and then putting a Metallization down the end to connect them all together you can create Quite a large capacitance in a small area just by making a multi-story capacitor so to speak and That’s still the layers of insulation in these it’s still going to be super thin you’d need a microscope probably to see all the layers where you are going for a High voltage capacitor the size has to go up these are also 100 Nano farad. So you look at this one. It’s 109 fire It’s really small, but it’s a low voltage one when you’re increasing the voltage you have to increase the thickness of the dielectric the insulation between them and

To make this type of capacitor these are metallized film capacitors and it’s a film that’s metallized on one side and they take two strips of it, and they basically sandwich them together and the plastic aspect of it is the insulator and the metallization is the electrode and to fit a lot in a small area they then actually just spiral the take a big long strip and they spiral it round into a small area, and that’s what creates the sort of larger area and The thickness of the plastic film itself will Determine the voltage rating This is a ceramic disc capacitor usually quite low values. It’s usually one of the simplest and it usually is just a disc of Ceramic with a conductive layer on both sides and then an electrode that just comes across and comes off and then it’s dipped in insulation, but you think that even this one this one is rated 10 nano farad and it’s rated [1000] volts, but To get that 10 nano farad the installation must be really really thin in the inside. I’ve never actually opened one of these up Let’s open one of them up right now and take a look Ohh. Not the thing to do with your snips That is so it really is wafer thin in there. It’s so thin that most of the thickness of that is the protective coating That is super thin in there. I don’t know if you can even see that it just looks like a line So electrolytic capacitors are one of the more exciting capacitors, and I don’t mean that in a good way the electrolytic capacitors to achieve such a high capacitance they contain a liquid electrolyte and they have a a very thin foil inside and the foil to create an extremely thin insulator they form an oxide layer on the aluminum foil in there and That means it really is like Micron thick which means that they can get a very high capacitance in a small area, but to couple onto that surface. They have to use a liquid [electrolyte] which then because … if you looked at the Foil it would look all pitted and mottled with that oxide coating so to get a good coupling They use a liquid that just fills in those gaps and that’s one of the downsides of well one of many of the downsides of the electrolytic capacitors because traditionally and all the old say for instance, all the old video games from the 80s Tend to suffer problems after a while with what’s called drying of the electrolytics, so they still measure the correct capacitance but their equivalent of resistance the resistance to current flow through them changes it increases and What that means is that They stop doing their job properly. When you get the large values like this. They’re usually used to smooth ripple so say for instance you had the output from the mains was rectified and you had a big peaky, Sort of like the The AC full wave rectified AC waveform. Which is like the two sides of a sine wave then by putting this across that it then just reduces it to a very slight ripple and a nice smooth DC voltage and as that Capacitor dries out over time that ripple will get bigger, and it ultimately starts causing problems when it dips down So low that the electronics can’t sustain normal operation, and that’s when you have to change capacitors However, that’s a more of an issue with Modern electronics because whereas in the old days the capacitors only had to deal with a 100 Hertz or 120 Hertz, just mains frequency rectified Nowadays the capacitors have to deal with the output from switch mode power supplies which is like thousands of Hertz tens of thousands of hertz and it means that they actually heat up and they Dissipate more energy. They’re just put under a lot more stress, and if you look at the top of this one you’ll see this little cross on it, and that’s a safety vent because When these fail what actually happens is that oxide coating is Can be perforated and that’s really common if you accidentally connect them in reverse because it relies in the polarity to keep that Oxide coating intact when you connect them in reverse that fails, and then suddenly you’ve basically got this Liquid filled thing just connected across the power supply with no current limiting it just basically it turns into a sort of resistor and it boils the electrolyte and when that happens the top will either sort of if you looked at it from the side bulge up and but if it goes too far that x that’s etched on to the Top will split open and it will vent out the top and the other option there if it doesn’t do that is sometimes it blows the whole can off and

it just makes a mess it gives out a vapor of the electrolyte, which is slightly caustic and it Can unravel the foil across the room it can go off with enough Force to actually cause injury if it hits you So you have to be kind of careful with electrolytic capacitors? so erm What have we covered? Let’s look at diodes now Diodes come in various flavors. They are used for various functions you get signal diodes rectifier diodes and light emitting diodes The function of a diode is to allow current to flow in One direction, but not the other So the symbol for a diode. oh, I didn’t mention the symbol for a capacitor was that basically representing the two metal plates with an air gap in between and in the case the electrolytic the That has the positive and negative are marked with The positive being the sort of just the empty box and the negative being the filled box just for the polarity reference However moving on to the diodes the symbol for a diode is very easy. It’s very self-explanatory In the water equivalents thing it would be a pipe with a one-way valve in it So the water could only floor one way in this case you have the anode of the diode and the cathode spelt with a “K” I’m not sure why they do that there must be some reason. I’ve never really investigated that too much but Current will flow positive from the anode it will flow through the diode to the negative but if you try reversing the polarity very little current if any will flow through that diode in reverse and The main values you have to consider with diodes are the current you want to flow through them say for instance This is a one amp diode. That’s rated to handle one amp flowing through something like a 1N4148 signal diode it’s not designed for anything major. It’s just designed for say rectifying small electrical signals, so it’s only rated about 100 milliamps or so if that and The other Factor is the peak inverse voltage that’s what voltage it will block coming in the wrong direction so supposing if you did connect Well this one is a 1N4007 It’s rated 1000 volts so that means that it will block 1000 volts going the wrong Direction But if you were to exceed that dramatically it will avalanche and it will start conducting the opposite Direction So you have to choose the correct diode for the job This is a silicon diode which typically has a when it’s forward passing current in the correct direction positive to negative it will typically have a voltage drop of about point 6 volts and Sometimes you know it depends on the voltage rating actually sometimes go up to one volt and it also depends on the current flowing through it you get Schottky diodes which have a much lower forward voltage of between 0.2 to 0.5 volts and in Cases of rectification that lower voltage actually makes them much more efficient the light emitting diode our Favorite type of Diode really is a diode junction That is optimized. It behaves like a normal diode, but when it’s forward biased when the currents flowing through it, it emits light and the very first leds were actually Here are some here, they look just like the 1N4148 diodes these are actually leds they look just like ordinary glass diodes, but these are really vintage leds and when you pass current through In the correct direction a little red dot glows inside them it’s very very dim but they were purely for printed circuit board indicators these days of course leds are used for illumination and have evolved greatly but one of the things you have to note with LEDs is they don’t have a very high – because they’re purely Optimized for emitting light they don’t have a high reverse blocking voltage it’s usually just about five volts So if you were to connect the polarity wrong in this and exceed about five volts then in the case of the white, blue, green leds that may damage them but with red ones they may end up just conducting but not lighting in the wrong direction but not suffer damage and so [em] let’s say the other diodes zener diodes a zener Diode is a diode used for voltage regulation or Voltage to provide a voltage reference It will act like a normal diode if you pass current through in the normal direction And it drops roughly about 0.6 volts, but you get them say for instance You want a 5 volt supply you get a 5 volt zener and when you apply a reverse current positive flowing down to negative. It will actually start conducting fairly Precisely at 5 volts