A comprehensive video showing the unboxing of the WP3W-RK 0.5W to 3W wireless power reference kit, a demonstration on how to use the kit, how to replace the coils for different power levels, and how to break down the boards into their smallest possible physical dimensions for prototyping.

Presented by Brett Rickard, application engineer at IDT. For more information about IDT's 3W wireless power reference kit, visit www.IDT.com/WP3W-RK.


Hello, my name is Brett Rickard. I'm an application engineer here at IDT and I'm here today to talk with you about our low-power wireless power transmitter kit. And here it is right here. This is what you receive in the mail and this is called a WP3W-RK kit. This kit is good for one, two, and three-watt power applications. The output would be at 5 volts, and depending on the configuration, one, two, three-watts, as I said.
So let's just get started and open it up and see what we have here. So inside, there's two sleeves, and on one sleeve, I find the TX and the RX. I know the bags look alike. I can tell because I'm up close. We'll be opening these up and seeing what's in the bag. And on the other side, you'll find extra coils because, like I said, it was a one, two, and three-watt kit. So the two-watt coils are already on the kit, and in this extra bag is the one and three-watt for the TX and the one and three-watt for the RX. And finally, you have a USB to micro-USB cord. This is for powering up the TX. We won't be using this. I'll just be using a simple wall wart, but either works. This could plug into your computer or just a wall wart, and you're good to go. 
Okay, so what we have here is, first of all, out of the folder comes the TX or transmitter. And you could see here, this is the 9235A-R. That's the chip and you can see the...here's the coil, our chip, of course, and here's the micro-USB connector where this gets powered up from. The next up is the receiver or RX. And again, RX coil, here's our chip, it's a P9027LP-R. And this is the whole receiver. You'll notice on this...I'll show you later. We're going to put them together, and we're using the PCB as the spacer between the TX coil and RX coil. So it's important to get the orientation of the coils right. And we'll talk about more on that when we replace the coils for different wattage kits. Right now, these are the two-watt kits, two-watt coils.
So the third part is, as I mentioned before, this is a one, two, and three-watt kit. So the two-watt coils are on the board already. But you can change to make it a three-watt system or a one-watt system. And how do you do that? Well, let's say you want to make a three-watt system. You've got a three-watt coil that has a white dot on it. It should be this one. That's for the TX. And with that goes a RX three-watt coil, which has a yellow dot on it. And that'd be this guy right here, yellow dot. Yellow dot's on the back. Here's the actual coil.
So these two go together, and here's the front of the coil for the TX. It's pretty easy to tell them apart because the three-watt like has big power, sort of, is also a big coil. The one-watt is a much smaller coil. So here's the TX one-watt, and you’ve got a red dot. Here's the front of it. And with that, very tiny, is a RX one-watt with a green dot on the back. Here you can see that. My finger's kinda big compared to the coil so maybe you can't see that. There you go. And there's the front of it, right like that. 
Okay, so what I've done here is I put the TX underneath and the RX on top. I just used these nice little vices to place them so that they don't move around on me while I'm unplugging and plugging. So I'm just going to move this aside for a second. You could see, here's the TX, here's the TX spacer, and the coil is facing up. Now, you want the coils to face each other. So here's the top of the RX board and here's that RX coil that's facing down so it faces the TX. And then, of course, the RX PCB is the RX spacer. You've got a TX spacer and a RX spacer.
So all I'm going to do is just put them on top of each other so that they lay on top of each other here. So we're going to power up the TX and you'll see these lights do a little pattern, and then one light will go green and it's ready to go. And then the RX, we'll see that this output here has five-volts. So here, I'm coming in with a micro-USB. This is just a wall wart plug. 
One thing, before I begin, if you're using this two-watt system, make sure your wall wart has at least 600 milliamps of current capability. If you're going to use the three-watt, make sure that current capability is more like 800 milliamps. And if you go down and use a one-watt system, make sure at least 400 milliamps of current capability on your wall wart. You can look on the wall wart. It'll tell you the output voltage, which should be five volts, and the current rating, maximum current. So of course, more is always better, but those are the minimum limits for a reasonable performance.
So see, I plugged it in. Lights doing a nice blinking pattern, and then the green goes on. That means it's transmitting. So I'm going to take this DMM, digital multimeter, and just so you don't think I'm lying, I'm going to look at the output voltage, which is right here in the corner. And sure enough, you see five-volts. So there you go. One last thing, I'm going to remove the RX and put it back on so you could see the functioning. Oh, and here is the RX light, that says, "Hey, I've got output voltage. I'm good to go." So I'm going to remove the RX now and watch these lights right here. Of course, the RX green light will go away. There's no more power. Then this will go away, too. See? So there's no more coil, no lights. Put it back on, there's a green light. Green light, you have power. You're ready to go. 
Okay, what we're going to do now, after seeing the part's energized with the two-watt coils, is we're going to replace it with a three-watt coil. So what you're going to have to do is take off the TX spacer and lift the TX coil itself off the PCB, and then lift the RX coil off the PCB. And then what I do is...right here and here is where they're soldered in. They're through-hole solders. So if you just apply a soldering iron here, you can pop them out. And then we'll put the next one in. So first, I'm going to take off the TX coil cover. Oops, the TX came off itself. Well, we can work with that, too. Here, I'm prying the TX coil from the coil cover. There's the coil cover that came off. TX is kind enough to come off by itself. You see these lines here. This is how you center the coil once you put it on. Bigger to smaller is the three-watt coil, the two-watt coil, and a one-watt coil.
So before I start my soldering...see it fits in the two-watt coil spot. Before I start my soldering, I'm going to go over here and lift off the RX two-watt coil. It came off pretty easy. A little X-ACTO knife helps out quite a bit. So I’ve already got my soldering iron warmed up. I'm going to bring that in, and a little, what do you call this, needle nose. And so get in here, I'm applying my solder to one of them, and here it came out. So that's one wire out. Let's see if I can work from behind so you can see in the camera. I'm doing the second wire here, just get that soldering iron in there, and it came out.
So there's the two-watt coil off. And here's where it went. I'm going to do the same thing with the one-watt coil. Let's tin up our soldering tip so it's ready to go. A happy soldering tip is a happy engineer. And so over here, you can see again, I'm just going to apply the soldering iron. And that came out pretty easy. So do other one, and that came out pretty easy. So our two-watt TX and RX coils are now off. And the next part we're going to put on the three-watt coils.
Okay, so let's just remove these two-watt TX and two-watt RX. We don't need those anymore. We are going to need the spacer again. So you could see over here, the white dot three-watt TX, we went over that before, here it is. I'm going to put this one on the TX. And after that is the yellow dot three-watt RX, okay? So let's pick up our TX. The ends look pretty good to go in without any tinning. So we’ve got to see if we can get out of that camera way so you can see. So remember, the face of the TX coil is going to be up. So let's get some solder on there, come on. There you go, went in. Okay. And here's the next one. And let's get that solder here, get the liquid, get the...solder into a  liquid, it goes in. Voila.
So now, we just kind of...what you should do is you should glue this down a little bit. If you've got a little bit of hot glue, that would be good. I'm just going to put it here for now, and it sort of stays because of the coil, I mean, because the wires are a bit rigid. So now, I'm just going to slap back on this TX cover. So there we go, pretty easy. So let's continue with the RX coil. That's the yellow dot. Nice long leads here so we can...easy to work with. Now this one, like I said before, the coil face should be down, so the two faces face each other. They really want to be together.
Okay, the next part is we're going to put on the RX coil. And this is, again, it's, look at the color code, it's RX, three-watt, yellow. And here's yellow, so check. We're doing three watts. The coil should be face down so that when I put the RX on top of the TX, the two coils are facing each other. That's what they like to do. That's how it's designed. 
So let's get our soldering iron in here again. This is a through hole. There's a lot of solder still in the through hole so I don't need to add any more. So I'm just going to make that solder go liquid in the hole, stick the wire in, and that's good to go. Oops, let me get out of the way of your camera there so you can see what's going on. So here we go, put that down there. And there you go, it's in. It's kind of long. You can shorten these. If you do, make sure before you put it in, you tin off the...see it has a copper color, you burn that off with your soldering iron to make, to expose the wire so that you can solder it in there. But any of this, you can cut it shorter. It's this part of the coil that really matters. So for right now, I'm just going to pull these off to the side, like that, and set the coil here. And there's some little stickiness there still so we're good to go.
Okay, so we've put on the three-watt coils, and you can see them here. Here's the TX and here's the RX three-watt coil. The TX is face up from the board and the RX is face down. So what I'm going to do is I'm going to put the RX on top of the TX. Now, I'm going bring in my five-volt micro-USB plug. I'm going to have to hold on both sides. And there, I plugged it in. It went red LED, green LED, and then it went red and green LED. And this, since I already had RX on, the green LED stayed on. And that says it has power, which you can see right here. The RX is saying, "I'm happy. I have output voltage." And I will show you that again like I did before. Black is ground. The red is the out. And you could see on my meter I've got five volts out. So this one can supply up to three watts, okay? 
So I'm going to take these apart and you'll see this light go away, of course. There's no power to our RX. But you'll also see this light go away, which means it doesn't detect the RX anymore. Here we go. And one last thing is you'll notice that you can...see, it's on, and it can transfer energy when there's offsets in the coil, but the efficiency is going way down because you're not picking up as much as the field and it's demanding more and more current through your input. So it's best, if you can, to line it up. That's the best efficiency. And at some point, it just can't transfer anymore, and it will tell you as I go away. See, it says, "Oh, I'm gone."
Okay, the last thing we're going to do here is we're going to break this board down to the minimum optimized, what do you say, real estate area. So we've optimized this board layout to go right into production. For user ease, we put on this coil part, which is not necessary, and we also put on these test points, which aren't absolutely necessary.
And that's true for both the TX...I'm sorry. I didn't tilt it up for you. We took this coil off before so I'm going to remove it so it's a little loose right now. But on these boards, this part, these parts are not necessary. The whole circuit area is right here. It's optimized to go right into production. And we suggest, we highly recommend that you use our layout for optimal performance. Same thing over here with the RX. You don't really need this coil part nor these test points on the side. What you only need is the part that's scored here, that little part right there, the little part around the chip and you'll see as I break it apart.
What I'm going to do right now is break it apart so that you can see exactly how small the area is and how easy it is to access that area just from the board itself. So first thing, though, is to take off the coils because, not necessary, not completely necessary, but it'll give you a better idea what I'm doing. You'll be able to see better. That's the reason here. And what you might want to do, once you've taken off the extras, is you can plant it right on your own product without even doing the circuit board. So I took off the TX three-watt coil there, and I'm going to take off the RX coil. It's a little squirrely because I took it out of my vice, and it's very light because it's very small. Excuse me. So there, I took off my three-watt coil. It's giving me problems here. Let's help it along. And I need a little X-ACTO knife here to wedge it out. There you go. Okay, got it out.
Okay, so here's what we’ve got. Here's your TX. Here's your RX. So our first part is really easy. We just snip off this coil support part of the TX. There's no wires going here so we just snip so we just go like this. It's already scored, very easy to do. And let's take off the RX coil part, also, since we're on that. Okay. Now, the other parts, you could tear these off with your hand. There's wires coming through here because of the test points. So what I recommend is take an X-ACTO knife, it's already scored, just drag it along there. You know, drag it along there a couple times, like this, just to get a clean cut, okay? So that's what I like to do. And then I go like that, bend it out a little bit, and then we give a little more cut just because I want to separate those lines good. There we go. Okay. See, came right off. So that's one side of the TX.
And now, I'm going to do the other side. You see how small this is getting. It's highly optimized. So I'm going to turn around, here's my TX again, just do it like five times or so. The more you do it, the better. I think that should be enough, though. Then I bend it a little bit. Yeah, hard to bend. And do a little more. Okay. And there you go. So this is the minimum TX size. You can see how small it is. My finger for comparison, there you go.
Okay, so let's do the same thing on the RX. The RX is really, really small. You could see where this would fit, gosh, just about anywhere, your watch, medical devices, anything portable. And here's the score lines right here and right here. So the same deal, you're going to score away like that. And then I’ve going to break it. Heard a break, a little more. Make sure you get in there. Let's not get too excited. And we break it, there you go. So that's one side. If you notice, there's more test area than there is chip area. I'm going to do the other side, too. Let's see. I might actually have to hold the test side because it's bigger. Yeah, the circuit side is too small for me to get my finger in there. So I'm just scoring away, score, score, score. And we're going to break it a little bit, give it a little more score. And then we break.
And here is the RX area, really, really small. So these are the minimum areas that you need for a device. There's your TX and your RX. And that concludes our cutting session. Okay, thank you for watching this video. Again, I'm Brett Rickard, an application engineer here at IDT, and you've been watching a video about our wireless power transmitting solution for three, two, and one-watt systems. So if you want more information and all supporting material, everything you'll ever need to design your product easily and quickly is available at www.idt.com. That's our main website and then add a /wp3w-rk. Thank you very much.