Embedded Files
Day 1
Summary of This Lesson
This lesson will focus on the breadboard, a component that allows you to easily make connections between components in an organized and dynamic fashion. This lesson will also introduce the Power Distribution Panel which is a component used on an FRC robot.
Lessons for Electrical Training on the website requires a Tinkercad account at www.Tinkercad.com, so if you haven't already, make an account on that website. Also, you can press the "Try Circuits" button in the circuits tab of Tinkercad to get an introduction of how to use Tinkercad's circuit simulation feature.
So, What is a Breadboard?
The breadboard, like the one you see on the right, has many holes, as well as colored lines. What do the holes do? Why are there colored lines? Why are holes in rows and columns? We'll introduce you to those in this lesson.
The picture to the right has blue, black, and red markings on top of a picture of a breadboard. The blue vertical lines mean that the holes under it are connected electrically to each other. The arrow pointing to the right just means that the pattern repeats. Notice how the top and bottom vertical blue lines are not connected, that is because they aren't connected electrically. Now, for the black and red lines, they are a in a similar situation. The holes under a black or red line means that they are connected electrically together, and they are called buses or rails. The black lines (both on the actual breadboard, and marked) indicate that you would connect the negative (black) side of a battery, or other power source, there. For the red lines, it indicates that you would connect the positive (red) side of the battery, or other power source, there. So, if you connected the battery that way, with red to the red line, and black to the black line, you can connect an LED with a resistor in series to the red and black line to power it, and you can do it for as many holes as you have. Let me show you what I mean.
Here's an imbedded link:
If you press simulate, the LEDs would light up, just like in the previous lessons. Except this time, we use a breadboard. The breadboard has a dedicated space exclusively for positive and negative, which are the terminals of the battery or power source. This is to make it easier and clearer to see how electricity flows through a parallel circuit, mainly because there is a dedicated spot for power, and that things are in a grid like fashion.
Now, I created a parallel circuit with two LEDs and two resistors. They are a little different in terms of how far up the wires go in the vertical connections. This is to show how connections made in the same column (from our perspective it is a column) that are not crossing over the divot in the middle of the breadboard means that they are connected electrically, like with a wire. The cool thing is, you can plug even more stuff in it to branch out to different parts of the circuit, like how the red and black rows (from our perspective, it is a row) have multiple wires branching out of it to power the two paths of the parallel circuit (the LED and resistor part). You will notice how the LED to the far right isn't lit up, even though the resistor and wires under it are in the same column, so it should light up right? In the center of the breadboard, there is a horizontal divot, which is represented with a grey line in Tinkercad, indicating that the column above and below aren't actually connected. Now what about the other LED that isn't lit up? All of the components for that LED are on the same half of the breadboard, and it is connected to the red and black lines, just that this time, it is on the upper half. What gives? On a breadboard, the top red and black rows, and the bottom red and black rows, aren't connected to each other. There is no wire or metal piece bridging the gap. So, if you want to use both the top and bottom red and black rows, you need to connect the red rows on the top and bottom, and the black rows on the top and the bottom, together. This essentially extends the connection to the battery. You can try that out. Go ahead! Connect the bottom red row to the top, and the bottom black row to the top, and you should see the middle LED that wasn't lit up before now light up!
So what actually happens below the holes? Simple. Below the holes are pieces of metal able to conduct electricity, and a sort of grabber or hook to keep the components in place. And that's basically it!
So to summarize the connections, the columns (again, our perspective) in the middle of the breadboard, which excludes the top and bottom with the red and black lines, are vertically connected together, but the divot in the middle indicates that the top column and the bottom column aren't connected together. The colored lines next to the top two and bottom two rows indicates that they connect to the battery, but the top two rows and the bottom two rows aren't electrically connected together.
If you need a visual, you can use the picture above, or right below this text.
Also, here's a nice video explaining the breadboard as well as some other tips
Using the Breadboard on Your Own!
Go ahead and try to use the breadboard with different components. Make parallel and series circuits, and also a combination of series and parallel (ex: have components in series that are in their own path that is within a bigger parallel circuit). Use a battery to power your components, and remember to connect the red end to a red row, and black end to a black row. Then, to power your components, connect them to the red and black rows. You can build off of the original circuit in the imbedded link. If you need to get to the link again, here it is:
So, you've played around with a breadboard, which we will be using in the future. Now we will discuss how it relates to the PDP (Power Distribution Panel). The in-person people will get to make connections with the PDP with different tools and wires, but you can still follow along through the descriptions of how that works.
What is the PDP?
The picture to the right is what an FRC Power Distribution Panel looks like. We use the Power Distribution Panel to, well, distribute power! You'll see that there are red and black ports, or terminals with holes on the side of the PDP, similar to how on a breadboard there are red and black buses. Components on the robot, like a motor controller as seen in the picture below, connect to these ports to receive power from the battery. The ports have a fuse in series with them to open the circuit if too much current flows through the port to prevent a fire. A fuse is essentially just a box with a wire in it that is meant to burn up at a certain current. The in person people will get to witness a wire burning up which demonstrates a blown fuse. There are different fuses with different current ratings on the PDP for different jobs. The smaller current fuses are in series with the smaller ports and larger fuses are in series with the larger ports. The components connected to the ports can use that power to do things like control and power a motor. At the bottom right-ish side of the picture, there are two giant holes, with the red + and white - signs. This is where you connect the battery's wires into the PDP so that current can flow through the PDP and be distributed to other components. Ask yourself why those holes are so big. To start off, what happens when you add more paths to a parallel circuit? More current comes out of the battery, since there are many paths for electricity to go through, and the effective resistance is lower than the lowest resistive path. Current remember, is essentially how many electrons pass by per second. The more electrons pass by per second requires a bigger wire, just like how the more water you have passing by per second requires a bigger pipe. A bigger wire would logically have a larger diameter, so that is why the holes on the PDP for the battery wires are so big, since the battery wires are so big due to the fact that ALL of the robot's current comes through those wires first and foremost.
Now if you look at the top leftish part of the PDP, you'll see some white squares. Right next to the squares are holes where you can put in small wires to power certain components. On the PDP, that section is exclusively used to power these components: the roboRio, the voltage regulator module, and the pneumatics control module. There is a marking next to it to let you know which one can go to which. Those too, have fuses to protect the circuit from fire and too much heat. Now the last part, the far right-ish section of the PDP. You will also see white squares, which also have holes next to them. That section is used for CAN (controller area network) connections. You'll learn more about it once we get into motor controllers, but CAN is essentially a way to send data (a message) to different components. The PDP actually doesn't get controlled by CAN, it is meant to terminate it. What this means is it removes the signal noise (disturbances) from the circuit. When you connect wires carrying CAN data to the PDP, it can get rid of the noise using a terminator resistor. You do not want noise in those wires, as it can mess up data going to a component.
Important Note on Wire Gauges
Wire gauges (in america, it is in American Wire Gauge, or AWG) are basically a standard indicates the size of the wire in terms of cross sectional area or diameter. The lower the gauge, the bigger the wire, the higher the gauge, the smaller the wire. So a 30 gauge AWG wire is smaller in diameter compared to a 6 gauge AWG wire. The larger the wire, the more current it can carry, like how a bigger pipe can carry more water per second. If you have too much current running through a not thick enough wire, it can burn up and cause a fire hazard. In FRC, the ports on the PDP are usually connected with a minimum of 12 gauge AWG wire, which means you can use 12 gauge AWG, or lower, like 8 gauge AWG. Since the battery carries all of the current for the robot, the wires connected to the battery need to be a minimum of 6 gauge AWG.
How to make Connections to the PDP
To make a connection to the red and black terminals on the side of the PDP, you first need to strip a stranded wire. What is a stranded wire? It is a wire with small metal strands braided together. This makes it flexible, and we need this kind of wire for the robot. We do not use solid wire, which is just a larger, single metal strand, since it is less flexible. You also need to keep in mind the wire gauge, or the size of the wire when making connections to the PDP.
To do this, you take a wirestripper, which looks something like the picture below, and the correct gauge of wire, then picking the same wire gauge option on the wire stripper you close it on the wire about 1/2 of an inch away from the end and you start pulling.
You should pull in a way as to strip the plastic insulation of the wire off to expose about 1/2 of an inch of copper wire. That exposed part goes into the port holes.
You'll notice that if you put the wire into the hole, it easily falls out of it. This is because there is a gate that you have to open, which is normally closed.
To open it, you can take a flathead screwdriver and stick it into the rectangular hole above the port and rotate the screwdriver upwards. You'll start to see the gate within the hole open up. This is when you stick the exposed copper part of the wire into the hole.
Rotate the screwdriver downwards to close the gate so that it can clamp onto the wire, then pull the screwdriver back.
And you've just made a wired connection to one of the PDP ports!
This process is the same for the big and small red and black ports on the PDP, except for the fact that you use bigger wires for the bigger ports, and smaller wires for the smaller ports.
Now, on to making a connection with the other power ports for specific components and the CAN bus. These connections are the same, and they are called Weidmuller connectors.
First, you take a small gauge AWG stranded wire, since the Weidmuller connection ports are also pretty small and that they aren't meant for relatively large currents. Strip the wire so that around 5/16 of an inch of copper wire is exposed.
Press down the white square with your fingernail or a small screwdriver. This opens up the gate inside.
Then, insert the exposed copper wire into the hole, then release the white square to close the gate for it to clamp onto the wire.
And that's it!
Day 2
Summary of This Lesson
This lesson will cover voltage regulators. Members will be introduced to how it works, how it is used, and it's application in circuits. Members will get to use the voltage regulator in circuits, either virtually or in-person, and will get to see how it relates to the voltage regulator module, an FRC component used on FRC robots.
Lessons for Electrical Training on the website requires a Tinkercad account at www.Tinkercad.com, so if you haven't already, make an account on that website. Also, you can press the "Try Circuits" button in the circuits tab of Tinkercad to get an introduction of how to use Tinkercad's circuit simulation feature.
So, What is the Voltage Regulator?
As the name suggests, a voltage regulator regulates voltage. Very creative name, I know, but really convenient! Essentially, if you have too much voltage from a battery and want to lower it, you use a voltage regulator. Higher voltage goes in, and a lower, regulated voltage comes out, which is what you would connect to the component that needs the lower voltage. Resistors do have the capacity to turn a higher voltage into a lower voltage due to voltage drops, but what a voltage regulator does differently is that it can turn a variety of higher voltages, into one singular lower voltage. This means that if you put in 10, 12, 15, 17, or 19 volts into a 5V regulator, it will still output 5 volts, no matter the input voltage. Of course, if you put in too much voltage into the voltage regulator than it is rated for, then it will burn up, since a lot of voltage means a lot of energy for every electron. So lets see this in action. Press the imbedded link below:
What the Circuit Shows
There's the breadboard again. From now on, we will mostly be using the breadboard with our components. If you aren't familiar with the breadboard, you can go to the lesson before this one, which is in week 3 on day 1. To start off, turn the knob that changes the voltage from the power supply and take note of the two multimeters' readings, and the brightness of the LED. You'll notice that if the voltage from the power supply is higher than around 9 volts, the brightness of the LED doesn't get brighter. This is because the voltage that it is connected to is 5 volts, thanks to the 5V voltage regulator which limits the voltage to 5 volts at its output. If the voltage of the power supply goes near to 5 volts however, like 6 volts, then the voltage regulator actually won't have enough voltage to output 5 volts. So the input voltage has to be a good amount higher than what its normal output voltage provides. Now what do the multimeter readings mean? Let's start with the left most multimeter, the one with the voltage setting. That multimeter reads the difference in voltage between the input of the 5V voltage regulator and the output of the 5V voltage regulator. So, let's say that the power supply is currently at 15 volts (you can change the power supply voltage setting in Tinkercad right now if it helps). This means that the voltage at the input of the 5V voltage regulator is 15 volts, since it directly connects to the power supply. The output of the 5V voltage regulator is 5 volts, since that is what it is meant to do, limit the voltage to 5 volts. So what happened to the other 10 volts? Remember how voltage is just the amount of energy for every electron? The extra energy that can't be used in the circuit at the output of the voltage regulator turned into heat (the heat is actually power, which is the voltage multiplied by current). This means that there is more heat with more voltage. Basically, every time an electron enters the 5V voltage regulator, the regulator would take away the right amount of voltage from the electron so that when the electron exits the regulator, it has 5 volts. That is what it essentially does to turn a higher voltage into a lower one.
How to use it
Looking at the picture to the right, you will see 4 things. Red arrows showing how electricity flows (using conventional flow), and three colored circles at the leads (metal legs) of the voltage regulator. Let's start with the circles. The red circle is where the positive red end of the power source like a battery or a power supply gets connected to. This is where the unregulated voltage comes in. The middle black circle highlights that it is where the negative black end of the power supply connects to. The letter G of the middle pin stands for ground, which you can treat as an indicator to connect that pin to the negative black end of the power source. Finally, the green circle highlights where you would connect the circuit that needs the regulated voltage, in this case, 5 volts. You can treat this pin basically like a 5 volt battery, connecting the positive end of the circuit to it, and connecting the negative end of the circuit to the negative end of the power source.
So lets look at how the electricity flows through this circuit using conventional flow (from positive to negative). It starts at the positive end of the power supply, then travels through a wire and part of the breadboard to get to the voltage regulators input. Then, electricity splits off in a parallel fashion into two paths, the ground path, and the output path. Most of the electricity moves to the output path where the main circuit is, but some does go through the ground path. Electricity in the ground path have not much left to go, since after that, they return to the power source and their journey is done. The electricity in the output path however has lost energy due to the 5V voltage regulator. Every electron now has 5 volts. Those electrons go though a wire, then an LED, resistor, and finally another wire to return to the power supply, which has the positive charges that attract the negative electrons.
Go Ahead and Try it out Yourself!
Try to make an LED circuit, and perhaps a motor circuit with the 5V voltage regulator (basically the same circuits, except you switch out the LED with a motor, and you don't need to worry about the direction of the electricity). A general rule of thumb: the input pin connects to the positive of the power source, the ground pin to the negative pin of the power source, and the output pin to the circuit that needs the regulated 5 volts.
Here's a video that sums up the voltage regulator. There's also a part of the video about printed circuit boards, but you don't need to watch that. To be honest, it's probably for a sponsorship.
Voltage Regulators in FRC
In FRC, we use the Voltage Regulator Module (VRM) to regulate voltage from the battery. The VRM doesn't directly connect to the 12V lead acid battery that FRC robots use, but instead it connects to it through the PDP, which was covered in the last lesson. So, battery power goes through the PDP, which goes to the VRM through the VRM weidmuller designated section on the PDP. The VRM has weidmuller connections both for wires coming from the PDP, and for wires going to other components that need a regulated voltage, for example, the radio.
What's Inside?
Inside of a Voltage Regulator Module, you can expect voltage regulators to be put inside that one package. There are other electronics inside, and as you might notice when you power a VRM, LEDs light up, indicating that there are other components other than the voltage regulators.
Using the VRM
The VRM is basically just a box of multiple voltage regulators at your disposal. You will notice that on the VRM, there is the regulated output voltage amount and the current peak (in mA or A). The reason why there is a current peak (which means that that is the maximum current allowed) is because right after the voltage regulators in the VRM, there are current limiting components that limit current (for safety reasons and to prevent damaging the components inside).
The red ports for the VRM that is not for the connection between the VRM and PDP are essentially the output pins of the individual voltage regulators. The black ports for the VRM that is not for the connection between the VRM and PDP are essentially just to return the electricity to the negative side of the battery, which is also called ground. The voltage output amount (and max current) is shown right above the port so you know which one you want to use depending what the component that requires a regulated voltage needs. So, if your circuit/component needs a regulated 5 volts of voltage and doesn't draw more than 500 mA with the 5 volts, then you can connect it to the regulated 5V, 500 mA peak section on the VRM, and you are set!
During the in-person meets, members will get to use the VRM with components that we normally use in these lessons, like LEDs, resistors and motors. The VRM will receive power from a power supply to allow members to see it working. Unfortunately, Tinkercad does not have a VRM component, so members at home like you can only imagine a box of voltage regulators (which is essentially what it is). Life is like a box full of regulators, you know what you're gonna get if it tells you exactly what you're gonna get.
That is essentially it for today!
In-person members will play around with voltage regulators and the VRM, while at home members can continue to tinker around with voltage regulators on Tinkercad to get some more experience with voltage regulators.
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