Know How... 132 (Transcript)

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This episode of Know How is brought to you by SmartThings. SmartThings lets you monitor, control and automate your home from wherever you are, using your smart phone. Right now, SmartThings is offering Know How listeners 10% off any home security or solutions kit. And get free shipping in the United States when you go to smartthings.com/twit and use the offer code Twit at checkout.

Today on Know How everything you wanted to know about PWM but were afraid to ask, how to school your quad, and steam pump.

Father Robert Ballecer: Welcome to Know How. It is the Twit show where we build, bend, break and upgrade. I’m Father Robert Ballecer.

Bryan Burnett: And I’m Bryan Burnett.

Fr. Robert: And for the next 45 to 50 minutes we are going to give you some of the projects that we have been working on so that you can take them home and geek out yourself.

Bryan: Kick back, relax and enjoy the show.

Fr. Robert: Open a brew. Or coffee.

Bryan: So what are we talking about today?

Fr. Robert: Well first, I’ve wanted to talk about something that is a little near and dear to your heart. We have been messing around with this idea of airbags for motorcyclists.

Bryan: Yes. Because that is a pretty big safety improvement for cars when they first came out. But, motorcycling is definitely dangerous and if there is anything that can make it safer I would more than happily try it out.

Fr. Robert: There was a show on Discovery during the whole Myth Busters thing and people were saying we should make things that are weird. One of the things they came up with was an airbag for motorcyclists. It was literally just a suit that would have airbags popped out of them.

Bryan: And I looked like the Stay Puff Marshmallow man?

Fr. Robert: Right. I remember thinking that is the stupidest thing ever. You would roll and die.

Bryan: Dainese was the first company I saw that came out with an airbag suit that they had made. You are still going to get hurt.

Fr. Robert: But you won’t get dead. But, the new generation of these suits have really been refined. And they do things like inflate a collar around your net to hold your head study because, as you know, one of the biggest problems is your head gets yanked in the wrong direction.

Bryan: And starts rolling around. This is somebody that has been using the MotoGP for a few years where they have sensors in the suit that detects an impact, Milliseconds before it happened and it just deploys away and they puff up and they slide, but it protects the neck, shoulders and collarbone and stuff. Which is usually what breaks.

Fr. Robert: And again the key is to absorb that first impact. In most impacts something like 85% of the force is in that first impact. If you can have a system that just absorbs that you could greatly increase your chance at the writer is going to survive. Here is the thing. The same company that makes the suits for rider’s have now turned their mind to something a little more differently.

Bryan: What is that?

Fr. Robert: at the start of this season’s Alpine world championship in beaver Creek Colorado skiers were launching themselves down the slopes at speeds approaching 90 mph. It is like riding a bike, but there is no bike.

Bryan: There is no brake.

Fr. Robert: They had state of the art helmets, gloves and that airbag suit originally designed for riders but adapted for skiers. This theme was called the D-Air Ski. And again, it is based off that motorcycle product by Dainese. Now it is a wearable airbag. The cool thing is that it has three gyroscopes, 3 accelerometers, GPS, replaceable old gas canisters so it is not an explosion like a car airbags. It is actually compressed gas filling the bags. And then it has lithium ion battery to power the system. Everything fits into a hardened pocket that is located at the back of you so it doesn’t affect your gravity. It is towards the back of the skier. The cool thing is that the system was developed over the course of two years. Alex do you have some photo’s to scroll through here. It allowed them during the development time to figure out what regular acceleration looks like and the body position would look like and what a crash would look like. Because you spoke about this. Knowing the difference between crashing or just making a hard maneuver is very important.

Bryan: Right. That is key to all the sensors that they have. In the pictures you can see it is in the little neck hump that they have on motorcycles. It provides you better aerodynamics so the wind is not pulling on the back of your head. But that is also a great place to put sensors for this sort of thing.

Fr. Robert: That airbag inflates in just a few milliseconds and it stays inflated for up to 10 seconds. So for the entire duration of the impact. They say it will absorb up to 60% of the force of that impact which is huge. They even tested a couple of false positive things. What they did was they had someone skiing and they said it off. Just to see if it would cause of crash instead of helping. But it didn’t. It allowed the skier to stay in control. So they are really refining that balance between protection and not losing control of yourself or your vehicle.

Bryan: Because if an airbag in a vehicle went off while you were driving, like if you bumped into a curb… I think that is one of the jokes that if somebody hit something, poof, and then they get hit by the airbag.

Fr. Robert: You see it all the time, remember in Fight Club they would hit the front of the car and either set off the car alarm or set off the air bag? Well, the sensors in the software has become so sophisticated and they use this in the Dainese product that it knows the difference between something hitting you or you hitting something. Because the acceleration profile looks different. And that is really the difficulty in creating a product like this wasn’t the engineering. The engineering was actually kind of easy. It was fine tuning the software to make sure that it only goes off when it is needed.

Bryan: That is really cool and I would love to try one. But I don’t know if I want to be the person jumping off the bike.

Fr. Robert: You are going to love this up. Because of the accelerometer and the GPS and the little computer you can actually download your ride. If you are a skier or if you are a biker it will actually tell you, this is your path. But it will also say you pulled half a G here, 3G’s here and you were at this angle here. You can actually replay the event throughout your entire right. That is actually kind of cool.

Bryan: That is awesome. I love that stuff. And looking over the data. There was a case last year when a rider went down at 190 mph and the impact that they detected actually went beyond what the sensors could record. But it was cool seeing that here he is riding along and there are a consistent amount of G-Force and then it spikes up and showed exactly where the airbags deployed in his suit and the amount of time it took to deploy and it was like .00 something of a second. It was quick.

Fr. Robert: My only question is if these are re-loadable. Because I would be the kind of person that would inflate it and then I would not have a release valve.

Bryan: You are about to get in a fight… well I know the ones from the racing that I watch can deploy twice. So if you crash more than twice there is a little canister that is in there and it will inflate and then slowly deflate.

Fr. Robert: That would be important for you. Because you don’t want it to in-flight and break. But for me, using it for fun…

Bryan: You want it to inflate as many times as you want. You know what they should really get you is a little pump.

Fr. Robert: That is not the same. That is a little different. When we come back we are going to start talking about PWM.

Bryan: I have no idea what that is.

Fr. Robert: Good. Because we are going to explain it. it is actually important. Whether you are doing Arduino projects or RC projects you want to know what PWM is. But before we do that, hey Bryan.

Bryan: What’s that?

Fr. Robert: Do you know what the best rated home automation system at CES 2015 was?

Bryan: Yes I do. The one that incorporates all sorts of devices that you would like to play with.

Fr. Robert: Yet. It is called SmartThings. Now, we are big on home automation. It is one of the things that we have been wanting to do on Know How for a while. But the question is how do you do home automation if you have a bunch of different systems? If you’ve got light controls from this manufacturer or door controls from that manufacturer and you've got sensors that you want to integrate into one screen so that you are not jumping from interface to interface to interface. Well, you could go off and buy some super specially designed high-tech house that will go obsolete in a couple of years or, you could get SmartThings. Now these devices that Bryan is showing off right now, this is the SmartThing Hub. This is the start of your smart system. This is CNET’s highest rated home smart system. It was at CES 2015 and it made a huge splash. It is called SmartThings and it lets you monitor, control and automate your home from anywhere using your smartphone. Now you can turn on your lights, lock your locks, you can change your thermostat and home security settings all through a single. And you don't need a different For every product. Which is important because you want that central interface for your house. Intuitive controls allow you to set the rules on your smart home through their free iOS, android and Windows phone app. With SmartThings you can customize the way your smart devices talk to each other. So now you can tap good night on your phone and the lights will turn off, the thermostat will adjust down and the doors will lock. It is one of the dreams of a home automation that you make it not just remote-controlled, but smart. And that is what SmartThings does. Now even more, you can keep your home protected with SmartThings by using their home security system. It includes motion detection, water detection and more. I love this part. You can use the security system to broadcast audio like for example barking dogs when someone rings your bell. So that you can scare them away from your property.

Bryan: Fortunately I already have a Corgi for that. The best case I have found is that my shower is very close to our closet and it gets very moist in there so I got a dehumidifier but I have it running all the time because I don’t know how bad it is in there. But with the humidity sensor I can just set it to a certain level.

Fr. Robert: You can use the Hub to set that perimeter. When the humidity gets about 40% turn on the dehumidifier. And when it gets down below 20% then turn it off. That is the sort of stuff that SmartThings lets you do. It lets you take the home automation the way you want to do it, not just the way a manufacturer is going to give it to you. But say, what are the problems in your life that you want solved? SmartThings helps you solve it. Now, SmartThings was named editor’s choice at CES 2015 and what we want to do to help you get started out on your smart home, SmartThings is offering Know How listeners 10% off of any home security or solutions kit. And you get free shipping in the United States when you go to smartthings.com/twit and use the offer code twit at checkout. A better home, a smarter home now. We thank SmartThings for their support of Know How.

Bryan: There are so many of those.

Fr. Robert: You know the hardest thing about SmartThings?

Bryan: Is putting them all back in the box the way that I found them.

Fr. Robert: Bryan, I want to talk about PWM.

Bryan: Okay. What does that stand for Padre?

Fr. Robert: Pulse, width, modulation.

Bryan: Pulse, width, modulation. Why is that important?

Fr. Robert: Because you take a pulse and the width of that pulse and you modulate it.

Bryan: You have not helped me.

Fr. Robert: Okay, folks. Let’s go on to the next segment. PWM quite It simply is a way to take a clock cycle. We need a way to keep time with the beat. And convey some sort of information with that clock cycle. Now to understand why this is important, let’s talk a little bit about the difference between an analog signal and a digital signal. If you live in today’s world you probably know what digital means. It means that it is either on or off. And analog can mean that it goes analog. Analog has an infinite number of values. Digital can be used to approximate analog but they are two different types of signal. And to show that off, I’ve got two very poorly drawn waves here. This first one is what you might see in an analog wave. If you remember math there are actually an infinite number of values that N can represent. Let’s say that this is one and that is -1. So this wave can be any of the values between one and -1, which again is infinite. It just depends on where it is located in this curve. These two are what a digital wave looks like. There is no smooth curve because it does go between one and negative one. It goes between one and zero. It is a switch. It is only on for only off. That is fantastic because it also means that you could have a bit more accuracy. One of the things back from the analog age was that along with this infinite number of points was the infinite number of inaccuracies. Because the difference between .000000001 and .00000002 was so small that unless you have really accurate equipment you really couldn’t tell the difference. So in digital, I know it is on and I know it is off. There is no uncertainty. Which is why we like using digital communications. That at times it has its issues. Here is one of the issues. If I can use an analog wave to represent any number that I want, a representation of a digital wave is going to be more difficult because I only have those two values. So for example, this is actually two clocks. There is one tick here, and one tick here. If I want to to approximate what that analog wave could be, what I can actually do is I can turn it on and off really quickly. And then take the average.

Bryan: Is that what you are showing here?

Fr. Robert: That is what I am showing here. In this is one complete clock here, it is on the whole time. So this would be the maximum value. Let’s say this is an eight bit value and I have 256 possible values. On all the time would be 256. This is on half the time so this would give me 128. Now, that is good for digital values converting digital values into something that you can approximate. But the other question is how do you use this to communicate with analog devices?

Bryan: Okay. So, you are going to show us how?

Fr. Robert: I am point to show you very quickly. We have been doing our first ever Coding 101 Know How cross-over with Smitty, someone I met at DefCon. What he has been doing is showing us how to turn these voltage meters into a clock using Arduino. The way that we are doing this is using PWM. The question he had is how do we represent time which has a lot of values with a digital output which has two values. He has been using this. So he has to fake and analog signal because that is what is going to drive these meters with a digital device.

Bryan: That is by turning it off and on at different rates?

Fr. Robert: Off and on really quickly. So if I have values between zero and one. Zero and 10. If I have it on the entire clock cycle that is 10. If I have it on half the clock cycle that is five if I have it on eight ticks of that clock cycle it is eight. That is how I would get that value. I am going to show you how it works very quickly by doing this demonstration. If you could hold this right here. Take that and slowly turn that knob. Let that go and now spin that knob very quickly.

Bryan: Oh yeah. Oh. Whoa.

Fr. Robert: Calm down. This is how servos work. You give it an analog value and the motor will try to approximate where that value is.

Bryan: That is cool.

Fr. Robert: Lets go ahead and up the ante a little bit. We are going to hood your servo tester up to the old lunchbox. Take that puppy and do the same.

Bryan: Aw.

Fr. Robert: This is the basis not just for the Arduino but we were using PWM to tell the time with an Arduino but we’ve also been using it in Project Lunchbox and we’ve been using it in all of our Quad Copters. PWM is the way that the receiver speaks to the flight controller and the flight controller speaks to the Servos.

Bryan: I’m the physical connection to the remote.

Fr. Robert: What this is doing is that it has to encode into PWM, so it’s not just sending it one volt or five volts what it is doing is if you have it half way, it has the wave on half of the time and off half the time. If you have it cranked over all the way it is all the way on. If you have it cranked all the way over it is all the way off. As you increase it is going to gradually increase the amount of time each clock cycle that the wave is on. It does that a couple of hundred time, maybe a couple thousand times a second. Which is what you want, because you want it to check as often as possible to see where that value is. Which is why when we were talking about speed controller on Quad copter, remember one of the things I mentioned was that you wanted a speed controller that was fast.

Bryan: Because you are going to be giving the Quad Copter a lot of different inputs.

Fr. Robert: And you want that thing to respond to your commands as quickly as possible. So what you want is you want a speed controller that has a refresh rate that is high enough it is going to be able to take those commands and turn it into something you’ve actually given it to do. If you have a slow speed controller you end up with motors that lag. So this is a speed controller, this is identical to one that we might use in a quad copter. And what this is going to do is send PWM commands to that speed controller and as I increase it, it will spin it up and down.

Bryan: Oh, okay.

Fr. Robert: Go crazy. This is how useful the PWM is. Because of all the places it will turn up. Not just in Quad Copters, not just in Arduino. Anytime you try to make an analog signal with a digital device you are going to be using PWM. Or anytime you want to communicate using that pulse, width, modulation you are going to be using PWM.

Bryan: It is doing its best to mimic an analog signal and that is really fascinating.

Fr. Robert: This is a cheap way, a very inexpensive way and a very durable way of getting information across a clock cycle.

Bryan: I do remember watching some of you and Smitty working on that clock and it was to get the finite movement on the little dial you had to really manipulate the signal to it.

Fr. Robert: Steve in the chat room has a really good question. He says it is hard to understand the difference between the wheel servo and the constant motor. In the motor the PWM is controlling speed, in the wheel the PWM is controlling degrees of term. I understand that but all PWM is doing is giving you a value between 0 and whatever. So in the servo here for the wheels it knows that this is zero and it knows that is full. Or whatever the top value is. For the speed controller it is the same thing, but instead of turning a motor in one direction or another..

Bryan: It is just going from zero RPM’s to whatever maximum rpm is.

Fr. Robert: Zero is no volts. I am giving the motor no volts. And the full value is that I’m giving it all the volts that I have. It is the same thing, the same principle but they are using the information in different ways.

Bryan: Very cool.

Fr. Robert: There we go. Now we have some more PWM stuff for you but before we get there, let’s go ahead and drop into our Coding 101 crossover. If you are here from Coding 101, this is the segment you are going to want to watch. Because we told you there were going to be certain things from the Coding 101 episodes that we weren’t going to cover. One of them specifically with how to take your meters and turn them into something the Arduino can use.

Fr. Robert: I’m here with my master builder, formerly my co-warrior from Coding 101. This is Mark Smith. We have been doing a project in Coding 101, you really should check it out. We are going to put this in the show notes, the link will be in there so you can check out the Coding 101 episode in which he has been showing us how to play with these Arduino. But this time he wants to show us why we need to convert these meters from measuring voltage into measuring current. You explain this a little bit on Coding 101, could you tell our Know It All’s why you need to do this.

Mark Smith: All right, so we have here an analog panel meter and so the way these work is that they have a little electromagnet down here at the bottom and it supports against a fixed magnet. And so if you pass a little bit of current through the wires in that electromagnet it will deflect this needle across the 90° from 0 to 15. This meter is labeled in volts. The straight line means it is DC volts and it is measured from 0 to 15. So you would expect that this meter will measure 0 to 15 V. If you were to put a 15 V or anything between zero and 15 V across the terminals on the back you would expect that voltage to show up on the display.

Fr. Robert: But we have a problem here. Because an Arduino will not put out 15 V. It will put out 5 V.

Mark: That’s right.

Fr. Robert: So how can I use this? If I can’t get enough voltage to get all the way to the top of the meter is kind of a useless meter for me right?

Mark: Well, no. The good news is that the meters are actually current meters. Remember I said you have to pass a current through the coil. The voltage is irrelevant. What matters is the amount of current going through the coil. The way you can convert a voltage to a current is using a resistor. Ohm’s law = IR. So We have a resistor there that goes between one of the studs on the back, goes through a resistor to the meter and then back out the other side. So what that does is if you put 15 V across there, the 15 V across that resistor will limit using Ohm’s law to 1 million. It is actually the resistance of that resistor plus the internal resistance of the meter. So if I remember correctly that is a 14.8 kilo Ohm resistor.

Fr. Robert: If I still had my learning I could read the back.

Mark: And then the internal resistance of the coil is about 200 Ohms. So it ends up being about 15 kilo Ohms. and so if you put a 15 V signal across 15 kilo Ohms, that will pass one mill amp of current.

Fr. Robert: So really these meters are cheating. They are lying to us. They are using this to convert current into voltage. But we are going to remove that.

Mark: We are going to remove the cheat and we are going to turn it into a one mill amp meter.

Fr. Robert: Show me.

Mark: So, I thought a nice soldering iron here. And so all we are going to do is we are going to take that resistor out of the meter.

Fr. Robert: You want a good soldering iron, you want a nice clean soldering iron. If you are having trouble heating up the item one of the tricks that Smitty taught us was dabbing a bit of solder onto the ends to help the heat flow into the component. But remember you don’t want to keep the heat on there too long or you will damage things.

Mark: That is correct. So try and do it as quickly as you can, but you are going to need… I just put a little dab of solder on their and what I am doing is just taking out the resistor entirely and putting the wire onto the meter directly. That is it.

Fr. Robert: That’s it. So, taking out that resistor turned it from a volt meter to a current meter?

Mark: Correct. That is it. And so now, if I were to put one milliamp through those leads it would read full scale.

Fr. Robert: And that is exactly what we need because even though we can only output between three and 5 V on an Arduino we can output different amounts of current.

Mark: Exactly.

Fr. Robert: So folks, if you want to follow along in Coding 101 to see exactly how we made this you are going to have to do an alteration to one of these meters. Where do they pick these up?

Mark: I got these meters on Amazon. Believe it or not. Analog panel meters you can get them all over the place. You can get different physical styles. I got a couple of different styles. I got these nice round ones that are kind of small.

Fr. Robert: I like the old aviator ones. We've got a place here in Northern California like about us. They look like old pilot gauges.

Mark: These are old bakelite…

Fr. Robert: Those are harder to change though right?

Mark: I opened these up and I couldn’t get to it without having to really tear the thing apart. But one of these is already one milliamp the other is 100 mA.

Fr. Robert: I would say get one of these on Amazon just so that you can play right away. If you’ve got a surplus store nearby why not go ahead and jump over there and see what they’ve got. How much did these cost?

Mark: Just a few dollars on Amazon. They were not expensive at all.

Fr. Robert: We will get some links for the items that you bought and put them in our show notes. So now that you know how to do this, you can go back to Coding 101 and figure out the programming you need to do to make the Arduino do that.

Fr. Robert: I hate that guy.

Bryan: Nerds. It is so cool. I helped you guys shoot that and that was fun to watch.

Fr. Robert: It was fun. I never thought about taking a resistor out of a meter. And it totally makes sense I should’ve figured that out. I was sitting there like an idiot thinking maybe I could use a relay and send more power to it.

Bryan: Just pop that little resistor out.

Fr. Robert: Yeah, done. Now we are going to be giving you more. In fact for the next three weeks we are going to be showing you the hardware side of that steam punk clock. We are not going to show you how to build the enclosure. Unfortunately my woodworking skills are horrible. I wish someone in the audience was really good at steam punk. I love steam punk. I have no artistic talent whatsoever.

Bryan: Me neither. Well, I have some. Compared to you.

Fr. Robert: And compared to you, Greg is…

Bryan: On another level. He is not here on Thursdays so his psyche doesn’t exist anymore.

Fr. Robert: Whatever. But we are going to give you more of that. Make sure if you are interested in what we are doing with the steam punk clock you’ve got to check out the last two episodes of Coding 101. And actually this week and next week we are going to complete the project. Because we’ve got hardware and software. This is the crossover thing and we been wanting to do this for a while because we know that computer engineering or electrical engineering doesn’t stand alone. They work best when you’ve got a little bit of each.

Bryan: Definitely. And, this show is all about learning new stuff. And building things and stuff like that. Smitty made a great point when he was here and saying you might not have a project in mind right away, but there might be a problem that you are having that you can solve by putting these things together. And if that takes Coding, soldering and a little bit of wood working I am more than happy to try that.

Fr. Robert: I have actually already repurposed Smitty’s code because what his did was to use the PWM to send slowly more and more voltage into the meter so that you could actually see what time it was. I used the same thing along with, remember our dancing lights project? A 49C transistor to make lights light up and dim according to music. Well that is the same principle. Now I have actually created a clock that has no meters but the color slowly changes throughout the day. It’s actually pretty cool. The cool thing is because I use one of those try strips, a strip of LEDs that will actually change colors depending on what voltage they are getting off of each channel. So luckily they had three channels and we had 3 m for the clock and so as the time changes the color of the strip changes. You don’t see individual LEDs you just see it turn from yellow to green to blue. It is very impractical but it is cool. It is Fucia o’clock! Again, it is one of those things where you do the project and I have it sitting around and who knows what it is going to do?

Bryan: You have no idea what it is going to lead to. We started our RC project with a lunchbox and then it led us to quad copters.

Fr. Robert: Mauve is a color right?

Bryan: It could be a flavor. Did everything just taste purple?

Fr. Robert: Let’s jump into some feedback. It has been a while since we been able to take a look at some of the comments that our folks have made in our G-plus group. Bryan, you want to take us away?

Bryan: So we are back to the quad copter’s with the feedback question from Andy. He wants to know how to carry his squad around. He wants a suggestion on any carrier or travel case for the FPV 250 which is the smaller one. He has been looking for some kind of aluminum case with foam inside. He would like room for everything to fit plus a little extra space for a larger frame if he chooses to upgrade in the future. And we do both have carrying cases. One that you gave me.

Fr. Robert: Before we do that let me show you really quickly one that someone in our G plus group had. Some people were talking about how I carry around my FPV 250 now that I have it. You know that it can be a little unwieldy. We’ve guide a picture of what Andy did. He is the same person who asked the question. You can buy these at Frye’s electronics or surplus stores.

Bryan: It looks like a Secret Service briefcase.

Fr. Robert: Exactly. Now that foam, you can cut into to make inserts so that it holds everything that is supposed to be in there. This is essentially the case that I gave to you right?

Bryan: You’ve got to be careful with the propellers. If you don’t want to be disassembling it all the time, it is nice to have a case that the propellers fit.

Fr. Robert: This one is nice. The as you said there is one issue and that is the way the props are. That is kind of a pain in the butt. What we have been doing is taking the props off and then store them that way. But…

Bryan: I have to bring wrench with me everywhere I go.

 Fr. Robert: I like being able to just pull it out of the bag and being able to go. Which is why I stole this from the basement.

Bryan: Don’t tell Burke. He was looking for this while you were gone.

Fr. Robert: We could use this for Barcelona. Oops, sorry Burke. Now here is a cool thing. This is my completely, absolutely ghetto back. Because it wasn’t designed for this. It is for a camera but I has this nice hardshell.

Bryan: And then a nice foam inside.

Fr. Robert: Right. But the important thing was if you look inside it is big enough that I can put the entire quad copter in there without having to take the props off. Now one of the reasons that I did this is because I can actually stack two of them. I like to go with two different quads. That is the one with the ridiculous amount of acceleration. Also has all my props right here in my transmitters and my battery. And because this is a semi hard case it means that everything is relatively safe. I did drop this off the back of the tailgate.

Bryan: You’ve got your toolkit in there and you’ve got your remote. What else?

Fr. Robert: On the sides I’ve got the chargers and the batteries on the other sides I’ve got additional tools for when I break things. This is the ghetto part. I got creative. This is just pick and pull foam. I had a bunch of this from the cases that I’ve got.

Bryan: It looks like a bento box for your quad.

Fr. Robert: All I did was that I made it into the form of my quad copter. Even the legs, so I don’t have to take anything off. I pull it out of the case and it is ready to fly immediately. And when I put it back in the nice thing about it is that it is nice and cozy and I don’t have to worry about bending a prop. And, I can actually take this out of the bag and shove it into a backpack. So these are kind of like portable units now.

Bryan: Oh, that is a good idea. Because what happened to me is I wanted to take this on a ride and I want to put it in my backpack that basically I just put the frame in and all the props and things and a pocket.

Fr. Robert: Then you have to stop and reassemble it. And if you are in a rush you have to worry about the props falling off. This is a ready state.

Bryan: Where did you get the foam? I’m guessing it was fairly cheap?

Fr. Robert: It was super cheap. It was excess that someone threw away. So I just took a bunch of it.

Bryan: Where would people get it if they wanted to? Amazon?

Fr. Robert: If you wanted to go super hard-core you could do something like what you have. Which is essentially a pelican case.

Bryan: Which I didn't bring. I rode my motorcycle today.

Fr. Robert: Everyone has seen a pelican case right? It is a Polycarb hardshell. Super super strong. And all it means is that it is going to be able to survive a lot of abuse. But this bag already does.

Bryan: The cool thing about the other case is that you attach some bungee cords to the top so I was able to fit my Syma here and just attach it to the top of the case. And then below is where the 250 goes.

Fr. Robert: I think that is kind of a trend for me and all of my cases where I want more than one quad copter. Either the Syma and the FPV 250 or in this case the FPV 250 and the crazy one that does GPS and FPV.

Bryan: My case has been that I want to fly both my quads and I fly the little one first to kind of warm up and get the old joints working and then I moved to the big one when I am ready.

Fr. Robert: People are asking if there is any alternative materials that I recommend. I love the pick and pull foam just because it is so easy. And actually this is kind of weird. What I had to do, I had to cut through the side before I pulled it. Because I didn’t want to cut all the way down. A smarter way to do it would be to get, instead of one big thick lump of pick and pull, get two half sheets of pick and pull. And then just pick and pull off the top layer. Bet you could also do this with just foam. Find junky foam. You are going to have a lot of waste problems. Because you get little beads.

Bryan: How did you cut it?

Fr. Robert: With just a kitchen knife. There is a nether way that you can do this and it is actually a project for a future Know How. Let’s just say that it involves… remember a couple weeks back when I couldn’t sleep and I went to Home Depot?

Bryan: Oh yeah, there was some project that you were working on?

Fr. Robert: Yeah, that is actually part of this. That much better. Okay next question.

Bryan: This comes from David. “I don’t know if you’ve all seen this or not, but I have to say it is beautiful. Would Instamorph be too heavy to make this work? Sorry for adding to the quad madness”. Never apologize for that. He doesn’t have a quad himself but his question is more of a theoretical one. And probably just a shameless attempt to get a shout out on the show. So, you've gotten that David.

Fr. Robert: Someone sent us links to the millennium falcon.

Bryan: My email blew up and twitter and Facebook. But, that is fine because this thing is super cool.

Fr. Robert: It is super cool. We will say this, David Wiggins viewed did get your shout out and you know what? Everyone gets one. And you just used up every ones one. So chat room go get him.

Bryan: Except for our next feedback question comes from Adam.

Fr. Robert: This guy is active in the group. Adam do me a favor. If you could record a YouTube video of you saying your name properly we could maybe pronounce it. Please let us know how to say it so we say it properly.

Bryan: And so, his question is about managed and unmanaged switches with VLans and link aggregation. So we are getting into the Enterprise tech stuff.

Fr. Robert: We do. But it is actually a good question because You can do VLANs and link aggregation with consumer stuff. For example if you are running DDWRT on your router. Here is the issue. We typically think of managed switches and unmanaged switches. Managed switches means you can do all that cool stuff, you could do link aggregation you could do VLANs. That is why it costs so much. There is a lot more hardware and a lot more software to make it so flexible. Unmanaged switches would be things like that the V port switch sitting on your desk that all it does is take one connection and it branches it out to others. There are no smarts in those. Typically they are dumb switches that don’t do link aggregation. In fact if you plug in two different links from the same switch it typically will turn themselves off. And they kind of strip out the VLANs. Remember of the lands are the virtual LANs. We will talk about those in a couple of weeks. We got a really good question about how to set that up.

Bryan: We are going to get more into that?

Fr. Robert: Oh yeah. But there is a midway. The midway is to go with what is called a smart switch. Which is not unmanaged but it is not nearly as good as a managed switch. It is right in the middle. Some smart switches will do link aggregation but the big thing for me is the VLANs. Because VLANs are important. If you have a network using VLANs and you plug in a switch that doesn’t support VLANs you get all sorts of funkiness. Best case scenario nothing will work. Worse case scenario is starts injecting stuff into the network, you don’t want to do that. But a smart switch is smart enough to recognize a VLAN tagged frame and pass it along. It may not actually understand what it is but it knows it well enough to say I am just going to push this out. I’m going to make sure it goes where it is supposed to go. For example if I have a VLAN that is set up just for my phones, so any time a phone plug then it gets put off in its own virtual network. The smart switch while actually be able to understand what is inside that packet but it will recognize that is a VLAN tag for this. I have a phone plugged in and go to that and the phone will continue to be able to speak through that unmanaged switch even though the switch doesn’t understand what is going on.

Bryan: All right. It is kind of like a Band-Aid, not quite as good as a managed switch.

Fr. Robert: Exactly. So can you combine managed and unmanaged switches? Yes you can. Do I do it? Yes I do. But if I had my druthers and unlimited amount of money I would do all managed switches. But since I don’t have $5000 to spend on every switch.

Bryan: Maybe someday. Dream sequence.

Fr. Robert: Now, I know that this was a light of information and we are going to make sure that everything gets put into our show notes. By the way, we are getting back into quad copters. This is officially the last episode of February. And we promised that we would not do a quad copter build until we got to March. Well guest what next episode is?

Bryan: Is it March already?

Fr. Robert: It is March. For like the next three months we are going to be upgrading the FPV. That is one of the very first things we are going to do. We are going to show you a couple of simple things you can do to your FPV 250 to make it perform better, to make it handle better. We are going to show you how to build one of the big ones, the dead cats. So that you can do these beautiful aerial photography.

Bryan: That is what I want to do.

Fr. Robert: I actually got you one. Go figure. And we are also going to be doing a couple of episodes on some of the support topics. For example, as we get to the bigger quads you are going to need to balance your propellers. You can get away with it when we were doing the little amateurs because they were so small but as we get bigger, but bigger props are going to add so much vibration to your frame that you won’t be able to get the video.

Bryan: You know the little blue thing you had on the table earlier? For those of you who might be put off about quad stuff we will be doing other things. I don't think I told Padre any of my plans because we've guy some RaspPi projects, bench networking staff. The RaspPi I want to do that main thing again because that has been over a year since I've done that.

Fr. Robert: I think we can update that.

Bryan: I have a wearable watch that I teased a long time ago and I lost when the Know Hole got moved and then I found it again so I will be doing the wearable watch that you build yourself. How to fix your old Xbox 360 and then we are going to try and do some beer segments. How beer is made, local breweries. And we are going to try and visit some of those places. So there is a lot of stuff we have planned out.

Alex Gumple: You just made all that stuff up right now didn’t you?

Bryan: I have a list. It is written out. You know what Alex? You are going to help me make all that stuff.

Fr. Robert: Before we say goodbye we do have a parting shot. Hey Alex if you ever wanted to build a tambourine did you know that you only need a tambourine?

Bryan: Mr. tambourine man?

Fr. Robert: I used to think this was so weird but then I started searching for it on YouTube and evidently in the huge part of the world that is how you drive piles.

Bryan: I have no rhythm I would never be able to do that.

Fr. Robert: I’d be this sad guy that I would climb up before anyone else climbs up and just went… pft.

Bryan: You’d be very valuable.

Fr. Robert: don’t forget you can find all of our episodes and our show notes, where?

Bryan: At twit.tv/kh and you can find a way to download in any format that will appease your device. Check those out, that is where all our show notes are. You will probably, after an episode like this, need to run through those and see what we talked about. So go there, subscribe.

Fr. Robert: We had a shout out about Instamorph. On my twitter feed they were wondering why they got a big boost of traffic?

Bryan: Thank Patrick for that. Because we talked about it before, but we had no good ideas until Patrick came on.

Fr. Robert: Look, Instamorph! It’s cool! If we had any artistic ability.

Bryan: Padre makes squares and I make little army dudes.

Alex: Those were ash trays.

Bryan: Here Mom. Here’s an ash tray I made you. I know you don’t smoke, but… right next to the clay coffee cup that doesn’t hold coffee.

Fr. Robert: Also, don’t forget we have a Google plus group. It is a very active group.

Bryan: Your mike is dead. Padre is done talking. So yeah, follow us on Google Plus. We’re also on Twitter. I’m @cranky_hippo, he is @PadreSJ. I should just finish up the show. I do want to give one shout out though to my sister in law, Krystal, I promised her I wouldn’t do this, but it was her birthday last week. That is the end of Know How. Now that you know how… go do it!