Hi welcome to Tear Down! Tuesday This is an old mailbag item that we got. It's a drag up, multi worn and it was sent in by Andreas and he's from Germany so thank you very much. Andreas sorry it took so long to get around to it. What it is is a warning system that's designed to detect different types of gases.

You might be able to see different senses in there, and this particular unit can actually accept different plugin modules for this. Up to I think there's 35 different sensors for 35 different types of gas or something like that with dozens of different plugins that you can plug into here. and it's a gas detection system. There's an alarm on the top and it flashes a light and sounds a big siren, loud siren.

you know, screaming if it detects, um, you know, a combustible gas or something like that or a lack of oxygen even for example. And they're used by uh, emergency servicers services for example, fire brigades uh, might have. these are used in the mining industry. any sort of underground, sort of, you know, uh, confined spaces type thing to warn you, you just carry it around with you.

Um, it's battery powered Carri it around with you and it detects all these uh, nasty, uh gases which could, uh, kill you or could, uh, explode or something like that so you really have to be careful so this could be relatively interesting inside. Although I think all of the interesting stuff is really inside the actual sensors uh, themselves and how they work. So yeah, I don't think we're going to, uh, get too much into that side of things. But anyway, um, it is an intrinsically safe product.

There's the intrinsically safe, the ex uh symbol there, and what that means is this is uh designed and certified to go in underground situations like mines where there are these explosive um, gases and things like that and well, it's not designed to ignite those so it doesn't matter how this thing is used, whether you turn it off and on, or you or it goes off, you know the siring goes off, or you plug the battery in or something like that, or it fails internally. it's designed to be intrinsically safe, so it doesn't ignite any of those gases. And there's a lot of certification which goes into intrinsically Safe products like this. So yeah, let's check it out.

It's got a dot matrix LCD this one is faulty I believe Um, Andrea said it was faulty. It was too expensive to repair, so they just, uh, scrapped it. It's got a Nikad battery pack in the back here, which we can take off. hey, there we go and D25 connector inside.

That's really rather interesting. Um, so this is the Nikad battery pack. uh, presumably got some uh, circuitry in here, charging circuitry and other uh, such stuff like that. but there you go that just plugs in and uh, we can got some screws on the back.

Let's open this poppy up and see. So the first thing we'll do is just take off this module. It is designed to come out so you can plug. They're designed to be user replaceable.

so like for example, if a uh, if the Fber Gade was on, uh, you know, on uh, headed to a uh fire you know, in a in a chemical Factory or something like that, they may decide oh you know they know ahead of time what factor it is and what sensors to put in here. They could, uh, just replace this module in here and it looks like we got a rubber surround so they could they could replace that on. Route There's a little Port there, obviously that's for uh, outside air I'm presuming that this has, maybe. well, it's got five ports I'm not sure you know that's a free air port there, but also there was a port on the side here, so I'm not sure if that's like the fresh air sensor or something like that permanently built into the thing because this is designed going to be uh, calibrated in fresh air so you can turn it on apparently and then run the calibration where you're out, you know, in the clean fresh air and then uh, that just, um, that just calibrate recalibrates the thing for the current ambient environment that you're actually in generally fresh air.

but hey, it looks like that doesn't come out. It looks like you so much for user user replaceable, it looks like we have to. Uh yeah, it's user. Oh okay, it's a bit compliant look at that.

so it is user replaceable. but uh, well. so much for the uh, so much for the fireman changing the thing in the in the back of the truck on route to a fire. Oh well.

so will that pop out? there? we go. So aha, there we go. And these are designed to be uh, Plug and Play modules. So I.E They've got little identifiers in them so that the firm inside knows which one you've plugged in.

so you don't have to reconfigure it or anything like that in software. You just plug it in. It's got an automatic ID system. It knows what it is and it recalibrates itself.

Now here we go. There must be some sort of pump system in here cuz this looks like uh, as we said, came through that filter, there's that extra intake over there and uh, possibly that's linked to the outside here so that maybe that's probably the pump. Um, so where they're actually pumping that around and for what purpose? I'm not entirely sure, but uh, like, how do you get these things out? They're supposed to be user replaceable. I Guess you have to get a pair of Plies on there and pull them out.

H Actually, that whole assembly in there, as we saw before is sort of its own rubber shock mount and I guess it's got to do that to reduce the noise and possibly vibration from the pump. I'm not sure if the pump continuously operates when you switch this on on I wouldn't think so, otherwise your battery life would be uh, uh, you know, wouldn't be great with this thing. so not sure what the deal is there. Anyway, you know, maybe it just, um, does the pump.

you know, once every 10 seconds or something like that. I'm not entirely sure how it uh, actually operates and then just you know, takes a sample every 5 or 10 seconds or something. perhaps. Now until we actually get down there and look at the labels.

I Don't know which ones are installed in here, what different types of Uh gases these are designed for, but you can see different types of top elements here. This one has got it's weird. It's got some sort of I don't know. uh, you know, rough metallic surface on it.

almost like it's little globules of solder or something like that. I'm sure it's not obviously. but uh, that's what me as an electronics engineer. that's what it looks like.

almost. Um, Anyway, we've got that particular service so it's acting as some sort of filter on top. These things are going to be filtered and this one has some some sort of membrane filter. I'm not sure what that material would actually be.

This one looks basically the same, but it's obviously designed. It's a different sensor designed for a different gas. They got different colors on them, so presumably they're different models. And this one here is a complete uh molded plastic case.

except for it looks like a tiny little vent hole in the top. That's all we got there. Why so small? These sensors? These actually can be blocked by uh, you know, water or gross humidity or something like that in the air. At least some of them.

So you just have to be careful not to. you know, Certainly wouldn't want to immerse this thing. That's for sure. The only way I can think to get these out.

Uh, apart from pulling them is give my hey, there we go, give it a good work and we're out. Look at that. We got ourselves. these.

These two have popped out. Aha. You can see the connectors down in there. show you those in a minute.

There we go. and this one down here which is in its own plastic cavity. I'm not sure why there we go? TDA We're in like Flynn look at that. Aha.

So it turns out this one with the plastic surround here is different. It's got a pin header. It's got a standard 0.1 in pin header. It's got a uh, polarity, uh, hole plugged up there.

So that's what this module plugs in for I Still don't know what it does. There's nothing. uh, ex sensor so that's intrinsically safe sensor C I don't know I'll have to, uh, take a close look at that and decode that to see what. uh, that is.

But anyway, it looks like there's maybe that one is for, like, semi-permanent uh installation. It's only plastic, but uh, perhaps that's different. Anyway, the other three physically use a smaller, uh, smaller pin pitch connectors there. and they're male instead of uh, female.

So entirely different. And that's what these sensors plug into and they're Plug and Play. So obviously they got some sort of ID system on there. whether Lubec there you go.

I've been to Lubec Fantastic little town in Germany I Loved it I Went to an organ recital in Lubec There you go, one of the churches there. um, that was something. Uh, yeah. So these are rather interesting.

Whether or not they do it with just like a resistor value or something like that, you could and the firmware just reads the resistor value. That'd be the easiest way to easiest way to do it. Otherwise, you could have like a a little Maxum you know, laser engraved ID uh chip or something like that, uh, perhaps or some sort of you know, e squ prom or um, you know something I squar C cuz you only got a couple of pins available there. but anyway, uh, so that's the raw sensor.

Whether or not these have any uh amplifiers in them at the bottom? I Guess we'll find out by taking them apart or whether or not they are are you know, analog output? just direct analog output. So we'd only Supply Like a power, we'd get analog output and then we'd have the ID the pin ID uh system. Whether or not that's the case, uh or whether or not they do actually contain an amplifier and the board in here is expecting. you know, a a correlated like, you know one VT analog output or something like that.

Uh, cuz this thing does. Actually, you know it measures value so it's got to have ADC It's got to be an analog output uh sensor and it does data loging as well. I think I forgot to uh, mention you can actually uh log data for like 50 hours or uh, something like that. So yeah, I don't know.

Might have to crack these open. but let's get the rest of the Box open first. I Think now it will be interesting to see inside if the PCB is, uh, conformally coded or not. Um, you don't have to for intrinsically safe uh devices.

although it may be probably not, it' be my guess. But uh, certainly would not surprise me if we found a conformally coded board. I Don't expect anything fancy I expect a you know, an eight or a 16bit micro or something like that driving the Uh LCD and uh with a ADC either build into the micro. if it's not uh, that a demanding a requirement.

that's a long screw or um, or whether or not uh, it uses an external you know Precision ADC Something like that could very well do, but we'll find out. But I Don't expect much else. I Expect a microcontroller on on the electronic side of things. a microcontroller? maybe some signal conditioning? That one.

That one's feeling quite quite weird. Almost as if it's slipping. So I don't know. Yeah, it's not just going to.

Oh yeah, hey, there we go. we're in. Tada Look at that. That's pretty easy.

I Think it's going to it's bought on the front for the PC Uh for the LCD as you'd expect, so the rest of this hopefully just pulls out. There we go. It was just held in with a a pin header on the back side of the board. There there's our oh yeah, it is conformally coated.

Yeah, there you go. You can see the gloss of the conformal coat. So yeah, it just had the pin header down in here. Oh the female and down there on the Uh LCD we've got our male pin headers down there which then plug into the board.

Neat. So what we've got here is a two board construction. right angle. uh, d25 as you'd expect.

so double-sided load on that. So there's quite a bit of uh, stuff going on on that board. but that's a processor as I said 8 16bit uh micro? Maybe some latches or something like that Very old school sort of design. Um, so I'm not sure the Vintage of this one, but uh, we might be able to get a chip date code or something like that.

So we got ourselves a battery for the battery backup of course for the real time clock. that could be the real time clock chip there if it is quite old school. Yeah, there's a 32, that would be the 32 khz watch crystal next to it cuz of course being a Data Logger you've got to uh, uh, date and time stamp everything and then, uh, probably some analog stuff happening on the bottom. perhaps.

but there is a secondary board here. I'm not sure if that's just it's well shielded look at that. They've really gone to town to put the uh, that metal foil all over that. That's yeah, that's really going to town.

so I'm not sure if that's part of the intrinsic safety of it or whether or not, uh, it has to do with um, yeah, just um, you know, in keeping out, uh, interference for the sensor board. So yeah, we got some circuitry down on there. can see some resistor networks and stuff like that, so we're probably oh yeah, yeah, yeah. I Think it's going to be chocker too.

so there's lots of analog stuff happening on here. but I think this is going to be a lot of old school. I Probably expect a lot of 74 series logic like I'd Probably expect these to be you know, latches or something. 74 series latches or something like that, perhaps.

And there's the top side of the board there. uh, this connector here is the pump output. so it goes directly up into the pump mechanism in there. There we go.

There's the uh, there's the reservoir for it and the pump just drives that boom boom on a offset shaft there. and boom. It just drives it in and out. Something like that, and uh, generates a bit of pressure.

Whether or not it's noisy, you wouldn't think it' be, you know, hugely noisy or something like that. So yeah, um, this as I said, most likely that oxygen sensor. if I can, uh, Google that part number. Aha, no, no, no, no, no, no, that's not an oxygen sensor.

that's going to be a pressure sensor. Of course, making sure that the pressure inside the system is still good, here is going to be your oxygen sensor. I'm presuming once again, it's an oxygen sensor. They've got that sensor going directly down to the analog board down there.

There we go. two pin header. That's a bit that's a bit dodgy in how you're doing. Look at that.

Don't like that. Gee, they could have done that a bit better. At least have a locking connector or something like that. Not impressed there.

And uh, the Uh. pressure sensor of course I could. Yeah, you can look up that number. there it is.

P6 Gf25 I Have no doubt that's a pressure sensor. Should have known that I used to work on pressure sensors a lot back in the day, but that also goes down to the analog board down there. Nothing special so that's what we've got in the whole system. So my guess.

Ambient oxygen sensor plus the plugin, uh units I Still don't know what that one down there is with the separate connector. It's obviously got nothing to do with uh, this pump system. actually? no. I stand corrected again.

I've gotten this out and it gets more interesting as we get into this thing. There's a vertical board. here. There's some sort of sensor board.

There's another sensor embedded in this part here. This is really interesting. This is why it needs a pump. It needs to flow the air across there.

I Still think it is the oxygen sensor but it's really interesting. Look: They got a mirrored a real like a polished mirror or something in there. almost looks like a gold type finish or something like that. which is you can see it's sort of welded on the back there.

so they obviously this. so this I don't think is a sensor. This is like the um uh, like a probably an infra aha I Reckon this is going to be an infrared lead bounces through there off the back. and we've got ourselves a photo sensor here which can detect the oxygen level.

Aha, that's what it's got to be. Just like those uh, cheap ass eBay pulse oxymeters. You can buy that uh clip on the end of your finger, they just clip on there and they put they shine infrared light um through your finger and based on that you can work it. uh.

based on you know, absorption and stuff like that, you can work out the level of oxygen in your blood I Reckon a similar sort of thing is probably Happening Here We got ourselves an infrared lead transmitting bouncing off the back and then you know, maybe you that why that? they've obviously gone to a lot of trouble there. It's not just a mirror, it's a specific type of mirror. so specific type of material. So whether or not that's doing some uh, filtering or something or some such thing I Don't know.

I'm certainly no expert on that side of things, but here's our second board down the bottom here. we can pull that off. There we go. They got a little Flex membrane going there, so it's all really quite a bit of a mess going together here.

so that's only a interface board. really? Nothing, uh, fancy there at all, but they've gone to a lot of effort to sort of integrate that in to that whole pump system. It just seems very convoluted, like they could have easily done something a lot more attractive and sensible than that I would have thought. And that plastic ring on that connector? there? It's just that it's a plastic ring.

So yeah, I to stop, but presumably to stop the wrong modules being forced into the wrong hle. So why they've gone to that effort? There's obviously one module, which you know they really don't want as part of this modular Um system. It's designed to be plugged into a separate connector. What that one is I don't know.

you'd have to read the user manual I haven't read the user manual? That' be too much trouble, wouldn't it? and it would ruin all the fun of trying to figure out all this yourself. Actually, this is getting rather confusing the more I think about it. I'm the first thing I'm I'm thinking now is that well, why do you need the pump? The pump isn't needed just for an infrared, uh, oxy meter for example that could easily work without the pump. so that doesn't make sense that they would need a pump for that.

So I Yeah, I don't know. Oh, I Get it. I Just got it. I Just got it.

Okay, yep. duh. Um, where does the pump go? Look at this bottom here. here's the inlet.

Okay, this is actually I Think this is is the inlet up here and that's what plugged into Aha, There you go. That was our port on the top. So there you go that's designed to plug an external probe into it. and then of course, when you got an external probe, you need the internal pump to suck it into the chamber in here to actually analyze it.

And I'm also thinking that this is may not just be an oxygen uh sensor, it might be doing other stuff as well. I I think I better go to the manual for this one. And yes, sure enough, it all becomes quite clear when you read the manual. should do that first.

Rtfm. um yeah, the internal pump is an optional thing, which look, he's a happy dude there. he's uh, checking a remote, the hose coming out there, and checking a sample port on this pipe. here.

it's probably got some stuff running through it. his checking whatever. you know for the presence of gases or something something within that pipe that it's a suitable level. and there you go, you can draw 45 M That's pretty good.

So there you go. So that, um, answers the question about the noise and stuff like that? Who cares? You know how quiet is, it's not continuously operating. It's only when you uh, choose the internal pump and they also differentiate between this which yes, uh, confirmed it is an infrared uh sensor that was, uh, pretty easy I Was pretty sure I wasn't going to be wrong there, but this, uh what they call a cat EX sensor which is the one that plugs into here, which is this, module. here.

you can choose to switch between these two and they might be the same sensor for the same gas uh, for example, not the same sensor, but the same are detecting the same gas. You can choose between two different types, this one which uses whatever method um and the infrared one. and there's a page which explains that Tada Here it is IEX So the infrared one versus the cat. So the infrared operates in environments with low or no oxygen Aha and the infrared one is immune to poisoning and inhibiting Uh compounds that affect this poor sucker here.

So there you go. So you can have both of those in there and you can choose um uh, well there you go. uh. different responses, different compounds versus catalytic sensor which is this one here.

So there you go. You can choose during operation which one you want even though they detect in the same gas. Useful for different environments. Terrific thought of everything.

So why don't you just use the infrared for everything? Well I don't know. I'm sure one of these catalytic uh sensors is uh going to be better performing in some situations and as it turns out, I believe this one is actually a methane uh sensor. but you can get uh, different types. You can get ones that do hydrogen and what's called nonan.

never heard of it any way for you chemistry Buffs out there it's C9 H20 Go figure now. I Figured out why we've got different sensors here. These are, well, in this case, this one's an oxygen sensor. There we go: O2 and this one's a Uh Hydrogen sensor H2 So these are just uh, regular sensors, but this one is a catalytic uh sensor.

As I said and this one is designed to. That's why it's got a different, physically different connector on it. It needs power for an internal heating element in there. uh designed to detect uh, combined combustible gases and this is the Ex sensor.

C And here's how it works. and Tada We don't even have to open it. This is what is going to be inside this sensor here and it looks like it's fully potted anyway. I Don't think I'm really going to be able to uh get in there properly.

thankfully. Uh Drer have provided an an exploded internal diagram. Fantastic! What we've got inside here is basically a catalytic bead sensor and it's based on the poist principle where yes, it's like a resistance, but the resistance value changes with the gas in there. So what we've got is we've got ourselves a a heating element here and a sensing element and basically you heat it up to a couple hundred Dees I'm not sure exactly what temperature it gets to, but heat it up very hot and what it does is actually burns the gas inside.

That's why you need the flame arrestor here. CU You don't want it to, you know, actually catch a light inside there and FL You know Flames to shoot out with these combustible uh gases. So that's what they're doing. which is funny in an intrinsically safe uh sensor.

an intrinsically safe device to actually burn the combustible gas you're actually trying to detect. Hilarious. Anyway, what they're going to do is burn the gas in there. and if of course, the more combustible the gas in there, the hotter it actually gets and which changes the resistance of the detector element.

which is a platinum uh coil and that's pretty much all there is to it. It's rather neat I like it and it gets even neater than that. The reason that they showed two coils here. one's not actually the heater element.

they're not actually showing the heater in there, but one. They've called it a compensator element and what that is basically doing is uh, that one is not reactant to the Uh temperature change. so this allows them. This is uh, built into a Wheatstone bridge circuit and that allows them to compensate for ambient temperature.

CU They got the one that changes with the gas. uh, the burning gas pressure in there, and one that doesn't, so that allows them to compensate for that ambient temperature changes. Brilliant. So yes, the gas inside here can actually explode.

because hey, we're trying to detect combustible gases. they're going to combust, right? So uh, to stop it? Yeah, they got this flame arrester here and a center disc inside the thing which basically, uh, controls the reaction. it I stops IT blasting out the end here. but it also, uh, stops the reaction internally.

So when it does, if it does explode, it sort of self- extinguishes itself. And that's why you can use these sensors in an intrinsically safe, uh, product designed in a combustible environment. Yes, they do combust it, but hey, do it safe you I might see if I can dig open one of these puppies and uh, Tada hello, hello, what do we got in there? a? well. let's see if we can't hack into that with a pair of side Cutters Brilliant! I've got my hacky pair of side Cutters not my good ones and what? That was a waste of time I don't know what's going on there anyway.

potted inside there by the that's interesting. no hang on o oh what is that? That's interesting? Jeez. I've never never encountered that before. Not sure what material that is.

No idea anyone got a clue. Anyway, there is a wire hanging off there. so I just broke it stuff in there I know, look at that. There you go.

That's weird. There's a couple of wires you can see them going that's soaked in some sort of well I won't call it electrolyte material, but some sort of soaked in something. and there's obviously some sort of sensor down in there. Not sure what right down in there and this, yeah, that wire was going through to the top of there.

so anyone? Anyway, if anyone has any idea how this hydrogen sensor works I don't know. and unfortunately, the Um PCB down in there is potted as well. a All right over to the PCB and uh I'll try and scrape off this conformal COA in looks like this one's coming off relatively easy. Ah I see an m in there? I see the Big M I see the Golden Archers and no, it's not mackers What? bloody Mickey D for you Yanks It's mackers here, so no surprises for finding a Motorola something or other.

Tada Motorola MC 68 L 11 Um, same. Well, basically it's a 68 Hc1. As you might be more familiar with, the L stands for the low voltage version, which goes down to wait for it folks. three volts.

but back then, um, that was absolutely stunning. So um, yeah, there you go. Obviously for battery operation, they're using a um, low voltage version. now.

this is probably all the uh, firmware in here, which is in that that puppy over there is probably all in Assembly Language it could be in C could have been originally written in C but more likely Assembly Language Because uh, to get a product like this certified as intrinsically safe, every line of code in this thing must be verified. You pay someone like a hundred bucks per line of code to actually go in and verify that it's all okay and it's not going to explode or something like that. So yeah, um, so more than likely written directly in assembler and those other chips. Yep, I was right.

Latches there we go: 74 HC 574s Is that a date code I can see there of the 27th week 01. Possibly the number on that one's not easy to make out, so get some of the magic spit and uh, put that on there. might come up a bit later. Better let me get the right angle on that and you probably can't read that, but uh, I can? It's just an NEC uh memory.

So yeah, that's just coupled to the processor on the other side and just some random ones next to 74 HC 320. So as I said, all these are probably going to be uh, just you know. Pretty generic 74 series logic. Nothing much happening at all.

Now this array of components down here is quite interesting. What do I think? There's no analog stuff happening here. This is another analog Lat, so all of this stuff is digital. So what This is because of its proximity down to the external connector down here for intrinsic safety.

What they've done is they got resistor limi in and diode clamping here, so that's they. That's why they've got so many in that symmetrical arrangement near the connector there. so all of the Io going to this connector for intrinsic, intrinsic safety reasons is all going to be Resistor, Current Limited, and Diode Clan. And you're going to see the same thing over here with this D25 connector as well and probably this external, uh, external connector here.

they're all going to have the same Arrangement and if we rip apart what we'll call the analog board here. Interesting. They got some marks on there. uh, they've done that before.

It was, uh, conformally coded. You can see the coding over that. so I'm not sure why they're marking there those cuz they just look like resistor arrays to me. Um, nothing fancy pany going on there at all.

They've got some board Some Like Elephant hide under there hot, snotted in place. That's interesting. That would be for intrinsic safety reasons. There's no other reason why they'd have that cardboard in there, that's for sure.

And uh, there we go. There's the bottom side of presumably our analog board fine pin pitch part there. Oo, fancy pancy stuff. Probably just some more 74 HC in a face stuff here on top would be my guess.

Um, and yeah, that is a four layer board too. Well, that's interesting. A Phillips PCF 8577 I squ C interface of course Phillips invented that um LCD driver. So there you go that's driving the big LCD the dot matrix LCD on the front.

Which is strange because they have a proper LCD module down there with the LCD drivers. So huh? And it seems that I don't have to scrape the conformal coding off this to see the numbers in there. if I get it at the right angle under my mantis microscope I Can see clean through the Uh conformal coding straight through the numbers and nothing is revealing. We got three opamps down here.

just uh, 27 L2s, Nothing happening, just you know. dual opamps. These are all 74 series logic all around here and well, nothing and all up here, so nothing else on the top side there and on the other side side here. We've got a couple of quad Uh opamps going on once again.

uh, 27 L4s there instead of the Uh dual version and some Maxes some 4,000 series you know, 4051 uh type Maxes going on around here, but that's it. So that literally is just an analog Uh interface board really going over uh via presumably this header cable here over to the main board. And of course, there is no ADC on this board or not as a separate chip, so it is built into the microcontroller. Of course this is an Eer Uh 68 HC or even though it's the L version, 68 Hc1 E Series So it's got an 8 channel 8bit ADC buil-in So yeah, fairly crude measurements, nothing fancy, but that's doing all your data login.

All your memory over there is holding all your data login, uh stuff. and well, yeah, there's not much else to it. Really fairly old school stuff. couple of opamps and and uh ADC built into a microcontroller.

Pretty much as expected, but of course the most interesting stuff is to be found in these sensors and things like that. Yeah, sorry I can't get that apart and the other one just didn't come apart. So yeah, I don't know, but this infrared uh sensor. rather interesting look they've actually got this is the infrared uh transmitter here, but they've obviously got another sensor in there and another something another sensor happening down in there.

It's a two pin uh T9 two package device just bent over at right angles like that and shoved through a hole in there. doesn't come out as a separate hole inside there though. Well actually that what I thought would be the infrared lead there is not. It's got like 4 Ohms and also given that looks like a just a bent uh T92 package like that potted in there too.

by the way, they got some potting compound down the bottom there so can't really get it out out intact. but um I am suspecting that that is a temperature sensor against the Uh against the top metal there that would be. That would be my guess about what's going on there cuz usually plastic T92 packages like that aren't a uh top entry uh sensor. even if it does have like a transparent or you know, a transparent um in encapsulant there, usually they're on the side, they're actually a sidey.

Metter So yeah, my guess is because they've got the top surface there attached to uh, you know, basically thermally coupled through to that metal. My guess and being two pin my guess. Temperature sensor. Although this being an infrared sensor, it is quite perplexing cuz this is obviously a three terminal device.

whatever is encapsulated in this side of the housing over here and this certainly isn't a uh a lead that's for sure. So unfortunately I've had no luck trying to get this sucker out. it just won't budge. I've taken off the retaining screw clip in there and it just ain't budging.

And curiously, that uh, reflective backing piece there, which is, you know, some sort of gold mirror or something like that, um, has got an individual serial number. Whether or not that's a serial number for the whole unit or whether or not it's just the serial number for that back surface. It could that important that they had to individually serial number and presumably test and characterize that before they actually, uh, welded that in place. H I Just had a thought.

Now I think I might know what's going on here. And by the way, check this out. You can see the angle on that mirror. I Just noticed that of course because it has to, the angle is going to be important to focus it down into the detection uh, chamber down in here.

What we've got what I think is happening here is that, uh, we've got a heater element here and that is what's um, heating up and generating the infrared Source We've got our you know, our polished and and perfectly uh, you know, aligned mirror that then reflects that down into the chamber down here. And what we've got is a reference temperature sensor down in here, a reference sensor uh, presum, presumably. And then we've got the actual detector for the Uh for the signal. So that's what they're doing.

It's sort of like a differential between the reference sensor and the temperature sensor under test, and then that way you can, uh, take out any ambient uh, temperature differences possibly I Don't know. That's my best guess. and if you're curious to see inside the battery pack, well, there we go. We got a conformally coded uh, charging uh piece PCB down in here, which then plugs it right angles into there.

That's rather neat. I Like that, and it looks like we got ourselves a baseboard that, uh, that's used as the connection. uh, the external, uh, external connection power through to the main board. So yeah, really interesting.

Arrangement Really looks like there's charging port on the uh top here, but that looks like it's all gunked up. Looks like it's totally sealed once again for the intrinsic safety. So yeah, that's really heavy and uh, probably fully potted. So I don't think there's any chance of me getting that out any time soon.

So there you go. That's the Drager or Drager I'm probably pronouncing it incorrectly I'm sure. multi-war it's the multi 2 um actually, and uh, that was really rather interesting. A bit more involved than what I thought and uh, rather is fascinating.

So if you got any more details on how say the infrared uh sensor and stuff like that works, then uh, please link it in cuz that's fascinating. But there you go. Whole bunch of detectors, fascinating technology, and I'm sure there's a whole bunch of you know really good science behind all this stuff too. You could do a PhD thesis on just you know how various different types of infrared sensors.

There are different types of these, um, different techniques for actually, uh, doing it. There's an open one which actually works in um, open air which is, you know, much huger than this you know, like in the scale of meters and things like that for you know, big uh, plants and and stuff like that detection. but this is fascinating how that's uh, just you know. Linked In like that.

and then you can plug a a probe on the top here and you can sniff things and fantastic I Like it. Fascinating technology anyway. I hope you enjoyed that. and uh, if you want to discuss it, the Evev blog forum is the place to do it.

the link is down below. catch you next time and.