Okay, welcome to Al's electronic classroom. As you know, we we are looking at how resistors are used. So let's go on to the next slide. We're on part two, as you can see from here, on the previous on part one, I gave you a little bit of a poem. big boys race out young girls, but violet generally wins. And I corresponded The, the color to the number to the first letter of the poem, for instance, big equals black equals zero, and so forth.

And again, I recommend that that if you forgot that or don't really know what I'm talking about, go back it's in part one of this series, go back and look at that and review that before we go on. Okay, on this slide here, we're going to see how the colors represent the value of The resistor. And in this slide here, we've got a four man resistor up here. And then we've got a five band down here, or right now we're just going to look at the four band. Now the first thing I want to mention is we have to know where the first digit is or what color represents the first digit. And if I look at this resistor, I want to find the group of colors that are to the left of the resistor.

So by looking at this resistor, you can see the group to the left is these two here are those three, they're all right, where the most left color. In this example, green is the first digit. All right, now, let's go over here and if you look at where it says colors, if you remember back in section one, I gave you big boys race out young girls, but violet generally wins. And we start from zero which is black, and we go all the way to white, which is nine. All right, and again I said earlier, if you don't see that, go back and review Part one. So looking at this again here, the first band of color is green and what does that represent?

That represents five. The color to the right of that in this example, blue represents six and on a four band resistor, the third band is the multiplier as I show you here, that is yellow and that represents 10 k Alright, so what do we have? We've got five, which is the first big color. We've got six, which is blue, and we have a multiplier of 10 K. So I can multiply that by 10 K. And previously, I've mentioned this k equals one, k equals 1000. So I can do this five, six times 10 times 1000. What does that equal 560123 zeros ohms 560,000 ohms or 560 because k Equals 1000 I can have 560 k ohms.

All right, again, all I'm doing is looking at the colors. All right and represent that color represents a certain number. If it's a four band resistor, the first band is the first digit. The second band is the second digit. And then I have a multiplier and I multiply that out. That's the value of that resistor.

Now I've cleaned off the slide and I want to talk about the tolerance. Now on a four band resistor, weak a four band resistor can have four tolerances. 10% 5% and 2%, which is right here. If you'll notice the fourth man on a four band resistor right here is the tolerance man So if I have for a four band resistor or a resistor that's represented by four bands of color, I can have a two, five or 10%. So the fourth band can either be red, gold, or silver. Alright.

Now, the posted value or the colors that represent the value of our resistor that we're explaining right now is right here. 560 ohms 560 k ohms plus or minus 5%. All right, that plus or minus 5%. is an upper limit and I'm going to abbreviate that ul and a lower limit Alright, so that resistor can go 560 k ohms 5% above and 560 k ohms 5% below. And I'm going to show you how to get that and I've got a blank slide coming up. We're going to go that I'm going to go through the derivation on that.

So let's go over there now. Okay, the value of my resistor as we know is 560 k ohms or 560,000. Homes. All right, plus or minus 5%. So what do we need to do first? First, we need to find 5% why percent of what of the value of our.

Alright, so how do we do that? Well, we take the 5%. And we change that into a decimal. How do we do that? Well, if I've got 5%, what do I need to do? I need to move the decimal two places to the left.

All right, so when I move the decimal two places to the left, I get zero dot. And it's very hard for me to show the zero. Like I said, I'm buying a new tablet for this. So bandwidth me zero dot and my dots right there on my decimal points right there, but we don't see it. Zero dot 05. All right.

All right. So now let's clear the slide. So what I've done now here is taken 560,000 ohms. I multiplied it by 5%. But here's my decimal equivalent zero dot 05. And when I do the math, I come up with 28,021 28,000 ohms.

So now, if you look, I got 560,000 ohms. And before we said plus or minus 5%. Well right now we know that that's plus or minus 28,000 ohms. Let me get the own signs here. All right, so now I need to find my upper limit ul. So my upper limit equals 560000 plus 28,000 ohms.

And we'll fill it will fill in we'll do the math and fill in the numbers in a minute. My lower limit equals 560 thousand ohms. He forgetting the ohm sign here, minus 28,000 ohms. And that's going to be my lower limit. So let's see what it is. And all I do is subtract 28,000 from 560.

For my lower limit and from my upper limit, I add 28,000 ohms. Alright, so let's do that. Okay, so here we have 560,000 ohms plus 28,000 homes, that's my upper limit because when I did the calculations 560,000 ohms plus or minus 28,000. Right here, what I show you right there. All right, so my upper limit would be five I've heard it at eight k home, because I take 560 and I add 28,000 to it, and my lower limit is going to be 532,000 ohms or 532 k ohms right there. So I have an upper limit and a lower limit, again, my upper limit will use right here, my upper limit is 588 k ohms.

My lower limit is 532 k ohms. So when I measure this resistor with a meter, some sort of meter if the resistor has a value between 588 k ohms to a lower limit of 532 k ohms. That resistor is good because it's in plus or minus 5%. Okay, let's look at another One, and I've typed this one out for you. All right, we have our resistor right here. And we we look for the body of colors that's closest to the left.

Here they are. And those colors are brown, black, red. So now if I look, the first digit is brown. If I look at my man one, right there, it's brown that represents one. Then second digit is black band two right here, that represents zero, there it is right there. And my third band, which is my multiplier, is red, which is right here.

And that represents 100. My tolerance span which is the fourth band here, which is silver, and that tolerance span is plus or minus 10%. So So now I just go through the math. The first significant digit is one, the second is 10. And my multiplier is 100. So I do 10 times 100 that equals 1000 ohms.

My tolerance is plus or minus 10%. Okay, and I show you that right here. Okay, first digit brown one second digit color black zero, third digit color red is 100. And so I multiply that the fourth digit tolerance silver, plus a minus 10%. So now I take my tolerance, which is 1000 times one 1000 times 10%. All right, I move my decimal point two places to the left.

So that gives me a point one Alright, so 1000 times point one is 100. Again, there's my desk, my percentage, and here's my decimal equivalent, I move the decimal places to places to the left. Okay, now my upper limit the value of my resistor plus 100. My lower limit 1000 ohms minus 100 ohms is 900 ohms. So if I measure this resistor and the low end it's 900 ohms to the upper end, which is 1100 ohms. If I, if I'm within that window, the resistor is good.

The only challenge here if you don't really understand is we have to take My percentage my 10% right here and we have to change it to a decimal. two places to the left. Okay, two places to the left. Okay, please continue on to how resistors are used Part Three