A gift from Vince secretary for our exploration. This is an illuminated audience wristband and you see these appearing a lot. They have more concerts these days. They have been around for a while.

They appeared in 2012 when Xylo band first introduced a product like this on the Coldplay concert. I Think it was the Milo Zalotto concert and uh, it's basically got a band of ground your wrist and this got the silicone a little. Springwood It's got a spring as well, but it's got a little catch here but it actually has hard plastic but it is used to actually grip the wristband inside. The unit itself is a set of AAA cells.

I wish I had some Triple E cells here to actually put in this. the ones that were in it. well, the ones that are in all the units he gave me at all leaked because of their long-term storage, but it's nice that it uses a standard cell. It's almost got a little Gap here that you can pull a tab out to actually activate these so they can preload the batteries in advance.

They make a thing. This particular company picks mob of air seeing that you can change the batteries in theirs and recycle them. You can reuse them, but let's go deeper. let's get inside.

So the concept of this particular version, which is infrared controlled is that once your audience is in and then during the show, this is going to be loud, crunchy noises. Probably you can make the audience response lay up in different colors at different parts of performance and it does this. Let's get down this: It does this using uh, these are RGB LEDs there. That's probably Pinmaker Control.

I'm looking for a boost circuit or does it run directly at three volts? Uh, there's an infrared receiver in the middle and I can see a smash of transistors that might be being used to drive the LEDs if they're not being driven directly by the chip. This is a flexible circuit board. Oh, it is. and it's just going on to the battery contacts here, right? Tell you what.

I'll do the usual I'll take the circuit board out, I'll take a picture, reverse engineer, and then we can explore the circuitry and see what's in it. One moment, please, Reverse engineering is complete. Let's explore. So what do we have here? We've got a flexible circuit board material.

Let me Zoom down this so we can see this closer. We've got a flexible circuit board material, which is quite nice because I could take a picture of the tracks at the back. which did help a lot with reverse engineering, particularly with relation to these tiny components here. the tiny little resistors.

Because they are so small, they don't print a value on them and it's just quite good to actually get a placement. Um, and babe, to trace the tracks through for such small items. Um, we have three transistors and they are driving. LEDs One of them is a PNP transistor and the other two are mosfets.

There is a reason for this: I Think they'd probably prefer to use the PNP transistors for cost reasons, but they've had to use mosfets because this thing does operate at three volts and that gives them very little Uh voltage overhead above the LEDs Particularly, the batteries start going down the batteries that were in it. Well, the cells that were in it were zinc chloride type cells. Um, and that will mean that the upper voltage from new is about three volts. That is very close to the LEDs but there's no boost.

Uh. things that took me by surprise. Well, let me show you a bigger version of this and I'll talk you through the circuit. This is me zoomed up into the middle.

So we have an 8-pin microcontroller as is so commonly used. Unexpectedly, there is this Akic Uh chip here, which I think is a memory chip and that's used to store a very rough address for these so you can have Banks of them in the audience and each one will react differently to the control signals. There's the two mosfets that A1 Shb is a peach animals fan that's controlling the blue and green channels and the Uh 2ty is a PNP in its control in the red Channel uh standard infrared receiver um only other Auditors Here are this little diode here for decoupling from the Uh process supplier which works at slightly below three volts. It's unusual.

Let's go straight to the schematic and explore this: I'll just leave a little soccer board there. It seems appropriate to do so. So here are the two AAA cells giving us a three volt: Rail and there is an element of decoupling for the power supply for both the microcontroller and the memory chip via this Schottky diode feeding this Uh capacitor and there's a there is a decoupling capacitor next to the microcontroller and one next to the memory chip lot that's a well-designed circuit. The infrared receiver has its own isolated Supply via the value that I measured in Circuit of the resistor 660 ohm and a little capacitor that just provides a decoupled smooth Supply Because these are a very sensitive, the infrared receiver here does contain not just the actual device that receives it infrared light, but it also um, takes in it, decodes it, it demodulates it so it has to have a very high sensitivity amplifier and that's why they give them extra filtering.

That data from infrared goes to the microcontroller which then controls LEDs and it does so via the two types. Transistors for the LEDs are very close to supply voltage. It uses a transistor with a very low Drop In this case an A1 Shb. it's a P Channel Mosfet.

It's the partner to the A2shb which is one of my favorite mosfets and this there therefore is my favorite pizza on a mosfet. I Guess the for the red LED They've got a much higher margin um, a voltage because the LED voltage is about 1.72 volts and they just use a PNP transistor for that, a T2y. And in the case of the mosfetch, they've got a really high value 82k I measured in circuit, pull out resistor to keep them turned off, and then they're driven directly by the microcontroller. But for this transistor, the standard bipolar type transistors, they don't need so much effort to keep them off, it takes more quite an effort to turn them on.

In this case, it's this 661 resistor. um, our nearest Value to that, probably 680, but that's what I measured in circuit and uh, that limits the current from the microcontroller into the base and to turn that transistor on. And then, oddly, there's just one 5.6 ohm resistor for the blues, one 8.2 ohm resistor for all the greens, and there's a there's four of those LEDs one, two, three, four. Um.

but in the case of the red, for some odd reason, they've got a 51 Ohm resistor power LED and I think they're effectively using them as links as well as, uh, because that it's not going to exceed the power dissipation. It also might be that maybe they found that the red LEDs just were better. They operate differently. it's an older technology, so better the current will be shared more even if you just have a resistor per LED as opposed to the blue and green, which if they're matched, will tend to balance off quite well with the current.

Um, so how are these actually controlled in the audience? Well, I Apparently Vince was saying that they used what looked like I'll zoom in a bit more than that Vince Said they used what looked like um LED Park Hands had been hacked modified with their infrared LEDs and that way when they wanted to control particular Uh bands, they'd send out the infrared codes to them and I'm guessing that you may be able to program each individual band with infrared, maybe give a code for its memory chip um to allow different sections of audience to light up in different colors at different times. There is a more complex system that uses Um infrared projectors and it can actually make the whole audience behave like a video wall, but they're quite complex and expensive. This one sounds a lot simpler. It's just washing the whole audience in a bath of the low level.

like like massive infrared remote controls. and uh, in doing so. Uh, they they just selectively switch colors and audience. Um, other things worth mentioning said that they had to give it its own DMX stream because I Don't know if it was using a generic DMX can, but it had to have a lower output rate.

It couldn't handle the full refresh of Uh DMX But there we have it. and the Pix Mob infrared controlled Audience wristband. It's actually quite neat inside. it's quite interesting and I like the fact that it does take standard uh, replaceable batteries.

Quite a neat device.