How to read schematic diagrams for electronics part 1 tutorial: The basics

so now in this video we're gonna look at schematic diagram so this is the first of a series of videos I do not have a number of videos I'm going to make I'm just gonna make them as they go as I think of ideas so if you have any questions make sure to ask them I will probably address them in a future video and during the time period I'm making them it's kind of awkward going back to a topic a year or two after you made the series of videos but in case we have physical resistors here those there and then this one here and if you see this symbol or that symbol usually they're all over in a more complicated schematic diagram that means it's a resistor you usually see either that one or that one that one the jagged lines is more common in the US and a bunch of other countries I don't know how many but they'll just use a rectangle with the value written I think inside of the rectangle whereas the value for this one is written on top so these are 220 ohm resistors this is a 10 ohm resistor a lot more current goes through here it gets a lot hotter it has to dissipate more heat so if you don't see a wattage rating this is 10 watt these are quarter watt so 0.25 you want to keep it about half of the rated value though but if you don't see a wattage rating it's probably one of these so we got the blue one and the beige ones the main difference is the blue one has one more stripe so you can get a little more accurate value of resistance and then it has a brown stripe at the end whereas the beige ones have a gold stripe at the end so the beige ones are 5% higher lower than the radio value the blue one 1% higher or lower than its rated value so I'm not going to go through that too much they're proudly in baggies that are labeled that ones that to kill ohms I got that from the make electronics kit these ones I got from an LED kit just a bunch of 220 ohm resistors and then this one's from my resistor kit it has the value written on the paper there but you should read the color code too so now I'm moving away the LEDs so the LEDs come in a bunch of different sizes the 5 is common and so is the three millimeter so we got the five millimeter baby they're three millimeter baggy I'm also used three millimeters they just fit on the breadboard really nicely they don't take up much space you can still see them whereas these are bigger and then that one's really obnoxious so LEDs are polarized they're a type of diode so you can see there's the diode sematic symbol and there's the LED schematic symbol so those are two separate components but LEDs are still diodes but they light up so these arrows kinda indicate there's light being emitted they are polarized though the anode has to be more positive than the cathode for it to conduct same with the rectifier dad there's some diodes that you use backwards for specific reasons but we're not going to worry about that in this video this is a basic electronics video so this one that's a large one you can see that the longer lead there that is the anode the shorter lead is the cathode if you have not trimmed it if you have trimmed it you gotta test it in some way the this green one here again long lead an old short lead cathode you're probably not going to see it but there is a flat edge on the Catholic side so you may be able to see that where as it's round all the way around the rest of the component but it's a little flat right there where the cathode is so that cathode is the stripe right there that's the way you need to wire it up when you're reading the schematic wherever it tells you to put this cathode you port you the short lead or the flat edge right there and not all of them as I said have that fetish so now let's move on the power supply so this is actually a schematic symbol for a battery one that you see here but and down here you can see another way you indicate the voltage so we're gonna use a five volt power supply generally I would use this schematic right there we got a couple other schematics we're gonna look at but that normally I would use this one for five volts but you could also have the battery symbol and maybe 5 volts maybe 6 votes maybe 9 volts whatever voltage they recommend you use and so if it's a battery it's gonna be some multiple of that type of battery so that's a topic for future videos the main takeaway is that's the power supply right there the schematic symbol for it and you connect the components to it based on the connections you see we'll get to that coming up so now they're switches so the old mechanical flip switch was indicated by this these push-button switches came out they fit on the breadboard nicely I don't have any mechanical switches that fit the breadboard nicely and so I think you'll probably see push-button switches more often now especially for just temporary presses saw this little one fits on the breadboard nicely this one's easier to see it's bigger and but I find it's less reliable the more I use these they don't make contact over time as well is that one but the in case there you can see it's a push button now the switch as long as you're happy with a push-button switch if you see in the schematic diagram one of these switches single pole single throw you can substitute it it doesn't matter all it's telling you is you have a way to make and break a connection right there and usually though with this one you put the arm whatever wherever the arm is usually it's inside the switch you may not be able to tell but you put the arm on the positive side and then the side that it connects to over there this means single pole single throw so that's telling you you have one path for current to go through when the switch is closed so sometimes there's another one of these up here you can either connect to that one or connect to that one and power to different circuits at different times and there's a bunch of other options but this is the basic mechanical switch right there and these are just single pole single throw so they're separated from top to bottom when you put them in the breadboard the way that the pins fit but if you press the button then this connects to both of those pins or that one connects to both of those pins so these two are always connected those are always connected when you press this those two pins connect to those two pins and it's a closed switch so now we're going to actually start putting together a circuit so these days this is really the first circuit you learn to make there used to be light bulbs before LEDs for even basic electronics and light bulbs protected themselves from a certain voltage where as LEDs do not they need a resistor to limit current to prevent them from being destroyed so we're gonna make one of the simplest circuits you can make now an LED that turns on or off depending on the position of the switch so again as I said before you may see a switch with an arm there so a single pole single throw one connection point you can substitute it with a push-button switch as long as the push-button switch meets your needs which this does so now you can see we got this one it's in a clockwise formation usually you follow a current path from positive to negative like that so we have the same thing here I added a little bit though a lot of times you'll see this symbol right there so that's ground that's our zero volt reference point we'll come back to that later basically that usually means that we're calling this zero volts right there normally we just do that but that's indicating on the schematic diagram that you're doing so and then in this case a five volt power supply we have five volts higher than that up here that's our zero of what reference point so again we'll come to that also sometimes you'll see a miss case for the switch S 1 and then resistor r1 LED LED one and there may be more LEDs it might say LED one two and then three and then switch one here there might be another switch that says s2 right there and you just more switches you got you keep adding an S and a number same with the resistor and then usually they'll be part of the sheet gives you some more specifics about it so here I wrote 220 ohm right next to that resistor that's more normal and sometimes you'll see both the 220 ohm and an r1 or whatnot so it depends on the source that you're looking at but you might have like r1 and then a note for it over there and then over here we got a normally open that's what Enel stands for it's normally open you have to flip it to turn it off the push-button switch mine are normally open and it's single pole single throw so again one powering point and then one connection point and then an open point single pole single throw and LED there maybe I'm gonna note to use a three millimeter for whatever reason and these LEDs they have a twenty milliamp maximum amount of current that you should put through them and that's usually what the resistor value is selected for so this to 120 ohm resistor will limit the current through the LED so in case that's some more information you may get from the schematic so sometimes they put extra information on there they don't leave you completely to yourself just with the schematic there so what we're gonna do we're gonna take a switch and it fits pretty nicely these little ones here into the board I want to make sure that that pins directly across there and then that pins directly across there I usually straddle there's no connection in the middle right there because nothing will connect to it and the board's trying to push this out a bit but in case we have that pin going there that pin going to there now we're going to connect that to the positive side of the power supply we have the power supply here it powers positive there and then negative there and we have a little jumper here so right now it's set to five volts it's turned off though if I move this jumper here then it will be 3.3 volts so that red rail will be 3.3 volts higher than that one now if I put it over here this is five volts higher than that one and we can work our way across - so we got five volts there five volts there we are going to take this jumper here and connect one side of the switch to the positive rail so we have that there so as you can see this just tells us the connection we need to make positive side of the power supply to the switch that's all this is telling us the actual layout and even the actual power supply that we use is up to us we don't have to use a battery just because the battery schematic symbol is there so I can put this here or here or I could use a little orange jumper it's the exact same connection for this particular switch now let's put it back over here just to kind of separate things a little bit more now we're gonna take the resistor you can see the resistor is the next component and resistors don't necessarily have to come before LEDs but normally they do and some people might be really irked if you don't put them in that order right there but electrically it does not matter so let's put that there and move this great jumper we don't need to connect it to this great jumper now let's grab the next component so there you can see now reconnect to an LED and this is where you have to be careful so the LED is polarized we just talked about that a little bit ago I'm not gonna go into that too much detail I can't find the LED up you're right back alright I got an LED here now so again this is polarized so this is where the long lead is we already talked about that so we have not trimmed this so it works pretty nicely if we trimmed it we would have to look over here there short lead has a flat edge so the long lead the anode that's the main thing though it's an anode connects to the resistor and then we're gonna put the short lead the cathode down one row so that's one thing I do is I work positive up and then down towards negative usually and also positive from the left to the right one or both of those now let's move this jumper and now you can see that the cathode of the LED goes through the negative side of the power supply which is the blue roll right there and so I'm gonna set that jumper right there make the connection and now as always you should double check the wiring I feel pretty confident I didn't miss anything and it looks pretty good I could easily I turn the power on this is getting kind of loose here so when it's newer it makes a better connection so we have the 5 volt power supply here I have a thing that plugs into an outlet and I can set different voltages I have 9 volts coming here and it's outputting 5 volts or 3.3 volts so there's range of voltage as you can feed it but it's got to be higher than what's being output so any case now you can see I hit the switch the LED comes on so this is about the simplest circuit and you're gonna see circuits like this in this form you just follow the same path for building it you should start building it on bread boards there's other ways to build circuits but these the components pop right in and out as need be you miss a connection you can just easily readjust the component and I fix it and whatnot it's great for learning these are called bread boards this is a breadboard power supply it plugs right into the breadboard really nicely as you can see there it's got these pins on the bottom and they go into the power supply right there also it has this right here USB this is an output so you can plug a USB in there and power something from usb if you have the right cable and now we're gonna look at another way you will often see schematics so we have the 5 volts up there that's to let us know we're using a 5 volt power supply and it goes to a switch same thing and we could put it as I said over here this jumper over there doesn't matter but it comes to the resistor underside of the resistor to the anode or the LED the cathode down there to our negative rail sometimes you'll see these lines there or a triangle to indicate ground and if you have multiple power supplies or something you connect all their negative rails together if it's a direct current like we have here and then each one of them can power different circuits they all end at the same point though in that way you can wire different power supply circuits together one can control the other or whatnot and as I said before things are usually drawn out where the more left side is more positive and the more right side is more negative and we don't have that here here we have a clockwise motion up here we'll look at we'll see more positive on the left more negative on the right here we have the more positive up and then the more negative down other side of the circuits there is clockwise so let's get to the next version of this circuit so now moving on to this one which we kind of saw a little bit earlier this one goes positive to the left working towards negative to the right and we're using again the ground symbol there's a five volt difference across here and there is more information written on here though so you won't always see this kind of stuff but I added some more analysis so sometimes you'll get information about the circuit added to it so that you understand the circuit better so what I'm telling you is when I close the switch first off the LED will light that doesn't not indicate it on here but we close the switch the LED will light as you can see there and we can estimate about fourteen point five milliamps of current is gonna go through this circuit because I know that about 1.8 volts is gonna be blocked by the LED that's just something I know from studying electronics and testing them out and what not so it's gonna be about that it's not gonna be perfect it very slightly more current going through it the higher voltage it's gonna black less current the less voltage it's gonna black but the thing is it's gonna block some voltage that's blocking the voltage from the power supply so it's gonna block about one point eight five subtract one point eight is three point two and so we can use Ohm's law that's what this is Ohm's law to calculate that so that will give us zero point zero one for five four five four infinity but ultimately you convert that the amps into milliamps a milliamp is one thousandths of an amp so you take that divided by a thousand and you get that and so that is what this is telling you and this is kind of an indication you're taking a current measurement there you don't have to and the thing about this number is that's the current going through that particular part there and it's also the current going through the led their current going through the resistor and the current going through the switch it's just a solid current when components are in series it's like a pipe with water going through it whatever water is coming in one side of the pipe is the same amount of water going out the other side there's only one path for it to go it's the same with electrical current it's just not quite as easy to tell that current is but that's the main takeaway so in case I also wrote here that there should be a 1/4 watt resistor usually you won't see that if it is a quarter watt I showed you a 10 watt resistor later and if you saw like 10 ohms 10 watts you would want to use that resistor not a quarter watt you'll burn out a quarter watt for sure if the circuit is intended for a 10 watt resistor so any case this is all stuff it's to inform you of these things and the nice thing is you can take a multimeter and actually measure it so that's what we're gonna do now and that's what you should do with analysis also I put the power down there the resistor in this particular circuit when we're pushing the button it's only having to dissipate about 0.04 6 watts of power so that's about 46 milliwatts of power and that's far less than an eighth of a lot you still want to stay about an eighth of a lot even if you use a 1/4 watt and LEDs you want to keep them under about 20 milliamps for most LEDs basically as much current as you need to to get it bright enough but no more and stay below 20 milliamps for the most part so in case let's take ya multimeter and I verify some of these things so first off the power supply when you see the ground symbol that lets you know that that is for the black probe so it says comm right there it don't see negative and positive it says common and then voltage there so that's the voltage in relationship to comm and normally common normally you put that wherever you see the ground symbolism so in this case we're gonna measure the power supply voltage these two points go directly to the power supply no matter if I go there or there or there they plug right into the rail and we get pretty much a direct connection no matter where we connect so right there you can see five volts for the power supply if the ground symbol was on this side of the circuit for whatever reason you may see that and you may see a negative voltage there and you can see that with the meter once I get a good connection there we go there you can see a negative voltage so sometimes there are negative voltages usually there's also positive voltages in that case but that can happen so the voltages are in relationship to ground that's what ground stands for for direct current is pretty straightforward that's zero volts and that's five volts higher pretty straightforward so now I have the voltage across the resistor and the LEDs now that is well the switch is closed let's look at the switch first so not all the power supply voltage is going to reach the switch because the LED is a semiconductor so it's still blocking some of the voltage from reaching the switch and there's a little tiny bit of current going through the meter because of leakage to to lower the voltage a little bit funny chase you're gonna see when I close the switch the voltage across the switch goes to nothing so the rest or all of the power supply voltages across the resistor and the LED so we got five volts about 3.2 it's probably not going to be exact is across the resistor and about 1.8 is across the LED so we can quickly look at that that is well the switch is closed and there we go so you can see it's not it's a little more than 2.8 so again these are estimates but they're good enough estimates you can quickly design a circuit with estimates and unfortunately that looks like both the voltage we lost across the switch it's kind of odd that it's negative that way but in any case this this is all just leakage so it's hardly noticeable current that is occurring for reasons we're not going to get into this video but in case it may take away we close the switch now you can see two volts across the LED and any case we have a 220 ohm resistor we can calculate based on the voltage across it so when I did my calculation I just went with three point two volts but it's gonna be close so with current measuring current we have to open the circuit so a one easy way to open the circuit is just to detach the resistor there now I got it way up here it's still connected across through there and we'll just look at 14.5 it's gonna be about that not exact so we got down here to the resistor over there the LED and so the anode of the LED will be the more negative side I gotta put the meter to measure milliamps of current so we're gonna go over there I feel really safe that it's in milliamps if we thought it might be near the amperage we would go to amp and move this plug to amp and verify it's less than 1 amp buy enough but we know it's going to be in milliamps the LED would have burnt out if it was anywhere near amps so there we go we set it to milliamps and this is the more positive side that's the more negative sign fortunately we have to open the circuit and press the button there you can see it's a little less than fourteen point five milliamps but as we saw before the LED was black did a little more current than I estimated also we actually didn't have to do this I'm a kind of bummed I didn't think of this earlier but it's kind of a good thing I did we have the switch the switch is open right now we can complete the circuit by and that's what you do when you measure current they're completing the current through the meter as I said every single series component is passing the same current when we close the switch it's not influencing any of the current the resistor and the diode are but it's letting current flow through it we're going to bypass the switch and let that current flow through the meter but that's why the current measurements are the trickiest ones to make and so no currents going through right now and everything looks so again all right there we go I guess the switch with an in there all right so there you can see we got the same current so we're just closing the circuit we're going around the switch it's going through the meter and then the resistor but we can take the terminals that are there and make it so you can measure the current that's going through a circuit well the switch is closed just by jumping the gap of the switch even while it's open and we could just go to a two points like that so so if you have a switch there it's really easy to measure the current as you can see there you can't measure the current while the switch is closed and you may get some reading but it's going to be off and if you don't open up the circuit you got to open up the circuit and have it go through the meter if you're gonna close the switch like that to get current to flow through there so hopefully that automates it the main takeaway is when you're reading schematics you may see some analytical information about it so circuit analysis is when you're actually paying a lot of attention to the exact values of voltage and current and other things so we just saw that we take a measurement there we could also measure the resistor if you have resistors you haven't learned the color code you don't know what bag they came from or whatever you can take the resistor put it on two separate rows and this is an auto range II meter we just have to set it to resistance there some of them you gotta watch the setting so like with voltages you got to put it to a higher then what you know it's going to be to avoid damage in the meter same with that crank at any case yeah we can just put the probes across there and you can see it's not quite 220 ohms but it's close these cheap ones I don't think our is accurate as they should be but still it's really close so with our circuits we don't need that kind of precision so this video went a whole lot longer than I thought but hopefully you still enjoyed it so thanks for watching I will see you in the next video

Channel: electronzapdotcom

Views: 129,433

Keywords: schematic, diagrams, electronics, how to, tutorial

Id: pmApobc3W1U

Length: 27min 9sec (1629 seconds)

Published: Fri Aug 16 2019