WEBVTT 00:00.080 --> 00:04.550 The first circuit we will do contains an LED and we will make this LED blink. 00:04.580 --> 00:04.970 Okay. 00:05.000 --> 00:07.460 And to make an LED blink, we will need an LED. 00:07.460 --> 00:10.550 Some wires, but also one resistor. 00:10.580 --> 00:15.650 The resistor is here to lower the amount of current that goes through the LED. 00:15.650 --> 00:21.350 And it's also helping to protect the Gpio so they don't get burnt with too much current. 00:21.380 --> 00:24.680 And for this course we will use one kilo ohm resistors. 00:24.680 --> 00:26.240 It's a very standard value. 00:26.240 --> 00:29.480 And I'm not going to give much details about this value. 00:29.480 --> 00:34.070 But if you want to know more about that you can also find many resources on the internet. 00:34.100 --> 00:40.400 So now that you know what resistor we want to use, then how to know which resistor to pick from the 00:40.400 --> 00:41.990 resistor set that you have. 00:41.990 --> 00:46.190 So maybe the resistors are correctly set per value in the kit you have. 00:46.190 --> 00:50.720 But if it's not the case you will have to read the value from the color. 00:50.750 --> 00:56.000 And here is a table to help you find the value of the resistor with the colors on the resistor. 00:56.030 --> 01:00.200 Usually you will have either four bands or five bands. 01:00.200 --> 01:01.190 Resistor. 01:01.190 --> 01:08.000 And here the first band, the second band and optionally the third band corresponds to a number, the 01:08.000 --> 01:10.720 next one corresponds to a multiplier. 01:10.720 --> 01:14.950 And finally, the last band is for the tolerance or the precision of the resistor. 01:14.980 --> 01:16.480 And for what we will do in this course. 01:16.480 --> 01:18.820 You don't really need to worry about the tolerance. 01:18.850 --> 01:19.120 Okay. 01:19.150 --> 01:21.010 Any value will do. 01:21.040 --> 01:25.510 Usually you will have here plus or -5% or plus -10%. 01:25.540 --> 01:28.990 Here we don't really need to care about the precise value for the resistors. 01:28.990 --> 01:30.280 And here's the example. 01:30.280 --> 01:33.940 With the resistor we're going to use the one kilo ohm resistor. 01:33.970 --> 01:37.360 If you have a four band resistor. 01:37.450 --> 01:39.130 So that's the one on the top here. 01:39.130 --> 01:42.220 You see that the first two bands are going to represent a number. 01:42.220 --> 01:44.350 So here one zero that's ten. 01:44.350 --> 01:46.990 And the third band is going to be here the multiplier. 01:46.990 --> 01:51.250 So to get 1000 you need to multiply ten by 100. 01:51.250 --> 01:54.220 So that's why you have brown black and red. 01:54.220 --> 01:57.160 And then you have the tolerance which can be any color. 01:57.160 --> 02:02.380 It doesn't matter if you have a five band resistor like the one I would show you just in a minute. 02:02.380 --> 02:05.440 Then we will have one zero and zero. 02:05.440 --> 02:09.460 So brown, black and black, those are the first, second and third bands. 02:09.460 --> 02:12.610 And then the multiplier is going to be only ten okay. 02:12.640 --> 02:16.990 Because we multiply 100 by ten to have 1000. 02:16.990 --> 02:20.920 So in this case you have brown black black and brown. 02:20.920 --> 02:22.690 Plus the tolerance. 02:22.720 --> 02:23.050 Okay. 02:23.080 --> 02:29.410 And if you are confused about, well, what side to read the register from, usually all the colors 02:29.440 --> 02:31.090 are you can see closed. 02:31.090 --> 02:33.760 So you have one bin here at each extremity. 02:33.760 --> 02:37.600 But most of the bins will be close to that first value here. 02:37.600 --> 02:41.560 So where you have more space here it corresponds to the tolerance. 02:41.560 --> 02:44.500 So that's how you can correctly read the value. 02:45.070 --> 02:48.490 So here is the resistor that I'm going to be using. 02:48.610 --> 02:48.850 Okay. 02:48.880 --> 02:50.800 So you can see I can read it. 02:50.800 --> 02:58.840 Uh here there is uh so I have five bins I have brown black black brown and then another color for the 02:58.870 --> 03:00.850 tolerance that I don't really care about. 03:00.880 --> 03:01.300 Okay. 03:01.300 --> 03:05.020 So if you can see here that's the resistance I'm going to use. 03:05.050 --> 03:08.050 If you have a five band resistor it should look like this. 03:08.050 --> 03:15.340 And then if you have a four band well you just have brown, black and red coming back to the color code 03:15.340 --> 03:15.790 here. 03:15.790 --> 03:19.000 If you don't have one kilo ohm, don't worry too much. 03:19.000 --> 03:24.310 You can also use 330 or 470 ohm resistors. 03:24.310 --> 03:27.760 So I'm giving those values because they are very common values as well. 03:27.760 --> 03:33.600 And if you have 330, for example, you can see that we first need three and three. 03:33.600 --> 03:36.600 So the first two bands should be orange. 03:36.630 --> 03:37.170 Okay. 03:37.200 --> 03:40.320 And then depends on if it's a four band or five band. 03:40.350 --> 03:41.400 The rest is going to be different. 03:41.400 --> 03:43.560 But you should start with orange and orange. 03:43.560 --> 03:48.270 And if you have a 470 ohm, the first two numbers are four and seven. 03:48.270 --> 03:52.770 So the first two bands should be yellow and violet. 03:52.800 --> 03:53.190 Here. 03:53.190 --> 03:53.820 Purple. 03:53.850 --> 03:54.210 All right. 03:54.210 --> 03:57.060 So that's how you can find a resistor's value. 03:57.060 --> 03:58.080 It's quite easy. 03:58.080 --> 04:00.180 Once you done this once or twice. 04:00.180 --> 04:01.320 It's very easy to find. 04:01.320 --> 04:06.810 And I would just recommend one thing is not going below 330 ohm for the LEDs. 04:06.840 --> 04:07.230 Okay. 04:07.260 --> 04:12.630 One kilo ohm is in fact a pretty high value for an LED with the Raspberry Pi, but it's a nice value 04:12.630 --> 04:18.270 if you want to connect many LEDs, so the total current consumption will not be too high and will not 04:18.270 --> 04:21.780 go beyond the Raspberry Pi's limit, which is 50 milliamp. 04:21.780 --> 04:28.230 So to connect components such as LEDs, the higher the resistor's value, the less current you will 04:28.230 --> 04:33.510 take, and thus you can plug more LEDs and components to your circuit while keeping it safe. 04:33.510 --> 04:38.520 And now that you know which resistor to use, let's build that first circuit with an LED.