Another gift from Vince the crew chief on the job I'm currently working on. It's another Uh audience illuminated wristband, but this one is RF controlled and it was in a bit of a state because it had got wet at some time and it had been a bit corroded. but it's not bad and the front comes off. there's a couple of screws underneath.

the front comes off, uh, revealing a compartment for presumably two, two, or three twos. There were no cells into the time, and there's a flexible silicone wristband. Notable that the connection to the battery is this really Stout spring in here. uh, that connects onto the side at the back for the positive, and the circuit board inside looks like this.

It's got. well, let's zoomed in a little bit. It's got a couple of chips, one in an area with an RF and 10 degree around the outside, and then one the middle, the ubiquitous eight pin chip. and there is a mysterious transistor down here.

I'm not sure if that's part of the powering on circuitry or not. Nothing really major in the back other than the negative battery contact and two more LEDs So there's two side emitting LEDs They seem to point outer side and these ones seem to point in the width. so there's four of these. LEDs Um, Well, okay, let's uh, reverse engineer I'll take a picture of this reverse engineer and we can explore the circuitry one moment, please and resume.

So we do have a generic eight pin chip here: common microcontroller, a switch, a little button on the side you can click inside the unit. We've got a dedicated RF receiver chip here with a crystal and then look at the LEDs which contain uh, the common positive here and they've got a red, green, and blue chip inside them. These ones are pointing in the way. or they've actually got a little arrow point possibly hinting at that, but on the other side of the circuit board, they actually bother showing it again.

they point out the way, so that's for even elimination. so that the one in the back are kind of lighting probably into the band to make it Glow and the other ones are lighting into the front of the unit to make it, uh, a light as well. And um, anything interesting about the circuitry. Yes, there's this transistor down here which controls RF section.

Uh, let me show you the schematic for this, because that will make things much clearer. just in case you aren't aware, this is a audience wristband that when you put it on your audience members with RF control you can during the show, you can actually make them light up. They first appeared ages ago like 2012 and Coldplay with their under the brand name Xyliband I'm not sure who manufactures these ones, but uh, it was such a popular idea that Zalaban had been ripped off rotten by many companies since they've many cops have been produced. So this one presumably uses two CR2032 which will make quite a higher voltage rate of 6 volts, so probably pushing the microcontroller to its sort of upper voltage limit.

All three colors of LEDs are in parallel with just a single resistor. I measured the resistors in circuit. They're tiny resistors and no value marks in them. It was about 360 ohm for the red, which is the slightly lower forward voltage therefore there's more to drop and 330 ohm for the blue and green.

There was a button uh, going to the zero volt rail for uh, turning it on, presumably maybe even put it into an automatic mode once. uh, although generally speaking, they don't want to do that because they want control over it. They don't want the audience finding ways to actually turn the lights on themselves better because that would disrupt from the effect. But there's a 5.6 K resistor, which is a standard value going up to this Uh transistor, a 2A PNP transistor which actually switches on the RF section.

So I'm guessing that the microcontroller can go into a low current sleep mode, but the RF section because it's always active and uh, waiting for an RF signal. it potentially has to be turned off just to save current, so the microcontroller probably only turns on Now I'm wondering the microcontroller can be woken by this button and then it could turn on Rfr. If it was in a standby state, it might just pull the RF every so often and just look for that signal to be present or it may just be there. Using this button as a simple means to activate everything just by waking the microcontroller up and then it turns Rf1 Oddity Here the C1 and L1 Lucas though they're in the wrong position here, but it might just be the markings of the circuit board because if you look at that shiny white component there, it's L2 and this is also the white component which may be the inductor and the C2 is the same color as this one.

Martial ones. They made both big capacitors and that would kind of fit, but because the guide to this particular chip the data sheet for it shows the output with a capacitor to the zero volt rail, an inductor capacitor, zero volt, Rail and then then 10 over there, another inductor to the zero vote. Real RF is such a science. Um, so I've drawn it as the manual has it.

but if these were um, actually a capacitor and inductor which I don't think they are I think they've just got a markings wrong, but I could be wrong here, then theoretically that would be an inductor down there in the capacitor there and don't think that is the case, but it might well be I'm not an expert in RF Maybe there are other configurations for this chip, but that is it. It's a very straightforward type of thing and you basically have the audience comes in. they're giving these wristbands and then during the show uh, at specific points when they want the audience to light up a specific color. uh, they send RF signals from antennas mounted around the stadium to actually activate the bands and make them eliminate I Don't know if this has the ability to receive data as well I think it may just be I should say send data I think it's just receiving I Don't know if you could selectively program them to different addresses I Kind of doubt it with this one, but I could be wrong.

But there we have it. the RF version of the audience interactive illuminated wristband. It's actually quite simple inside. it's quite a neat little device.