A look inside a cheap ebay smoke detector. 

my wife uses the smoke alarms for a cooking timer :P :)

I had thought at the start of the video that it would either be useless and never go off, or that it would be dodgy construction that could cause a fire on its own.

neighbour "you alright?" me "yeah why" Neighbour "heard a smoke alarm, thought i'd check b4 calling fire dept" me "no, it was a youtube video"

You're so calm, give great insights to what you do and just really nice to listen to. Let's face it, you're the Bob Ross of electronics!

"Ioization" might be their name for their photoelectric technology ;)

Wow that's quite neat. I didn't realize hitting the test button actually tested anything other than the speaker and battery.

In reference to what you are saying in the end... That's why a lot of theaters will actually use Both Ionization and Photoelectric detectors in them. They both have their strengths and weaknesses.

10 people were wearing headphones.

It got scared when you replaced the IR LED with a regular one... Imagine that every day, you go outside, and at the same time, your best friend on the other side of the street goes outside at the same time, and you wave to eachother, then you go back in. And you do this every day. Now imagine that one day, you go outside, and there is a stranger standing there... Waving....... I'd be freaked out too! Give the sensor back it's friend you monster!!!

They're selling "disposable" smoke detectors here in the USA. They're powered by lithium cells with an estimated 10 year lifetime. When the battery dies, you replace the entire unit. I guess that's good because the radioactive element has decayed significantly by then. Some people keep replacing batteries not realizing that it's effectiveness has diminished.

Never buy a Smoke Detector labeled "For Best Results Hold Directly Over Flame!"

Wow! Thanks for this BigClive! In the US, most smoke detectors are the ionizing type and there have been a few studies that show they don't work well for detecting smokey fires that are generally more lethal than open flames. I've replaced all smoke detectors in my house and in my parents' house with photoelectric ones.

Me: oohhh shit he is gonna put the battery in, (puts volume on 2)

-"Lets just open it..". Indeed. As a famous Australian bloke usually say: -"Don't turn it on. Take it apart!"

When you bent the LED out of the enclosure it started to beep because it couldn't detect the pulses. The same would happen when the battery runs low I'd imagine, and that was the mode it went into. Below a certain threshold it detects nothing at all from the LED indicating a low battery so it annoyingly beeps until you change it. Could be wrong but just the first guess off the top of my head.

Clive, i see your still vaping! I've have recently found your channel and find your videos both fascinating and highly educational. As a recently qualified electrical engineer I have learned principals and methods that 7 years in the class room failed to convey. I would love for you to pull apart some of the cheap "box mods" from china for analysis. Either way many thanks!

Great tear down Bigclive. I'm surprised to see that the chip in this supports multiple synchronized detectors. You pay much more for the ones that have that capability wired up and ready. Makes me consider soldering some phone line between a bunch of these inexpensive units.

The first Big Clive video I've found unsuitable for relaxed up-all-night viewing!

I think this one probably surprised us all, it is infact a reasonable bit of kit for the money. I personally buy the ones with the 7 year batteries now, as I get sick of being woken up in the middle of the night by the low battery beeps. I'd be interested to see the capacity of the battery in one of those. I will tear mine down when one dies, but that is sadly a few years away

Thanks for finding the datasheet, this was surprisingly fascinating considering it's just a smoke detector.

Ever since being a kid, i was always curious about all the detectors that have a radioactive warning on the sensor.. At the risk of exposing yourself to harmful radiation, a teardown of one of those would be awesome! But...just how active are they?

HOLY CRAP I CANT BELEIVE THAT THID WAS THE VIDEO THAT RU-vid THOUGHT, "SHE LIKES THIS CHANNEL" DARN ME AND MY SMOKE ALARM ENTHUSIASM CAUSE NOW IM SUBSCRIBED TO ONE OF THE MOST INTERESTING RU-vid CHANNELS ON RU-vid

your videos educate me in a subliminal way - often I take a sleeping tablet before bed and I watch your videos that are fascinating and full of information while in bed .....often my eyes will go and fall shut but I can still hear what you say ......and the next day my head is full of words like Nanofire micro henry resistors diodes ....don't know who microhenry is but I feel safe once I know hes there with you and I can sleep easy then ...... your video stimulate my mind with things I wouldn't normally pay any attention to ...so thankyou clive

Most of the UK fire brigades will give residential properties a fire safety survey and fit an alarm for free (this is cost effective compared with having a call out to a fire).

You are correct, these types will detect smouldering fires faster, the ion ones will detect the rapid burning fire faster. I use both types to cover all the types of fires. The ion ones can have a higher false detection rate and will trigger with very high humidity so don't install them near a shower or indoor pool.

I just threw my smoke alarm outside last night cause it kept making the "somethings wrong" or low battery beep, and it has a non-removable battery in it. Smashed it to pieces after actually waking up and now I'm off to the store to buy a new one.

That is very impressive, I wonder if the same chip and basic design is used in detectors which have the BS and or CE marks on them. If this detector was put through all the British Standard tests I wonder if the no battery feature would cause it to fail.

I have a normal smoke detector that likes to freak out when I play with my Slayer Exciter Coil. I'm not entirely sure why, it's a good 20 feet from where I usually use the coil.

wonder how good the ebay cheao CO detectors are, considering there less than a fiver

so did you try linking a few together to see if they all go off at once from just one detecting smoke?

A cheap way to get a (low spec) battery too. Quite amazing what's in these £2 items. I wonder if they get bankrupt stock to manage these prices? Surely that can't be manufactured for under £1 even if we exclude all labour costs.

Thanks a lot!! I played this outside and my neighbors called the fire brigade! 😀

Read any article about the Atomic Kid who tried and nearly succeeded in making an atomic reactor in his shed. He bought loads of detectors as one source of radioactivity. He also obtained thorium from the mantle of lamps and radium from old clock faces. The whole area had to be decontaminated.

As a firefighter here in New Zealand it's a really disheartening that most house fires where there was a smoke alarm but not working or not one at all. We have a partnership with a large retail store to supply smoke alarms cheaply to get them in every home, however the cheap ones like this one do require a 9volt battery and the cost of a 9volt that only lasts 2 - 3 mouths is the reason why people don't have working smoke alarms, and of course false alarms when the toast gets a little burnt is another reason why they ether get taken down to bench level or battery removal. And yes it's a standard for us here that if there is no battery inside it can't fit into the mounting bracket or close up. I recommend getting the Cavius wireless ones, not only do they have a long life battery of 5 - 10 years. Yes the cost of the unit is quite high to buy a lot but it is worth it. You need to have (photoelectric) one in every bedroom one in the hallway one in the lounge and one (heat) in the kitchen. With the Cavius wireless set if one triggers they all will alarm, giving all ocupents of the house time to get down get low get out. House fires of the older times had furniture that was resistant to burning, but in today's modern times and with all this synthetic metrails you only have 3 minutes to get out before the poisones gas's will kill you.

Wow, compared to most of the Chinese tat you find, like that big pink bug catcher, this thing is surprisingly serviceable, I could reasonably use this as a smoke detector without worrying about dying in a fire. Could you link the ebay seller you got this from?

Dammit Clive, had no idea you vaped! XD

You can test an IR LED by pointing your phone camera towards it and looking at your phone screen. That's how I test my TV remote control

as a rule I feel never mix cheap and safety equipment. I have a strong view on this when my parents bosch dishwasher set the house on fire. no one hurt,many thousands of pounds of amage. the circuit board behind the door started it.

Tell me why I am so addicted to this....

Very good testing you did. I bought 6 of them on eBay. I did my own smoke test by burning some leaves from the yard and wave the detectors over the the smoke... No beep, no alarm. No good? These 9v battery holder is on a soft plastic and falls apart quickly, not on a circuit board or a hard plastic. One good thing about them, very cheap, about $2.50 USD each. Why a cheap is good? I am a landlord and have a number of them stolen by tenants.

They are *extremely* good for places where smoke can fill the room slowly (ionization ones detect sharp increase in smoke particles) I have seen laser cutters with smoke alarms similar to this one. (if fan seizes up or vent is blocked or the material catches fire, smoke fills up the room and it sounds the alarm) And pranks. Wire either test button or the sensor (add 1~5K in-line resistor to the Vcc of LED and use transistor) to Arduino or ESP8266 and trigger the thing remotely :)

Clive was the "smoke" you used from your e-vape. I can see how this would work, as it did, for a photo-electric detector but would it also work for the ionising radiation type?

that beep you heard after you switched out the LED is a different chirp then the low battery chirp, It indicates degraded chamber sensitivity.

I use the exact same housing for a ESP8266 based temperature / humidity / particle count device that logs everything to a remote server via MQTT. I also made a hidden microphone that transmits on LW bands and draws almost no power

I bought 3 of this cheap ebay smoke detector this week.When i push the testing botton it chirps but when i test it with real smoke it does not.Do you think it will work in a real fire event?

My smoke detector is superb in detecting im making toast :-D, dam thing lol.

All of the amazing technology in the MC145010 for redundancy checks, and so many people don't bother making use of it by powering it when it needs a 9 volt battery replaced and then die from smoke inhalation in a fire...

Just noticed one with no wires coming to it on the ceiling and opened it up. Found a very similar board and a chip without any markings on it; and the chamber is totally the same. Mass production, folks. Mass production.

going to put this in my watch later... As I'm sure Clive sets it off at least once and it's like midnight right now! On the other hand... SUPRIZE FIRE DRILL KIDS... WHERE DO WE GO! WE HAVE PRACTICED THIS LETS GO!

I use my phone camera for detecting LED's on TV remote controls, not sure if it will work on smoke alarm LED's?

FINNALY! A product that is not a quack product, not a scam, and actually does what it is supposed to do despite the price! :)

How would you put a hush button on this device?

I bought an Asda (UK's Walmart brand) own brand smoke alarm about 7 years ago, that had an identical case, though it was an ionization version.

Good video. Would have liked to see what happens when you press the test button when the sensor enclosure is sealed, but the IR LED isn't present.

This is quite dated, but I thought I'd mention that all of the smoke detectors I've seen, which are all major brands, specify "Heavy Duty" (Carbon Zinc) batteries. (I looked up all the various part numbers they listed on the units). I suspect that it's because the drain is so infinitesimal, you're more likely to have the alkaline corrode than be a benefit. So, personally, I'll continue to put the batteries in that the manufacturer is recommending. (it's time for me to buy some new ones anyway, due to age)

I wonder what's inside the UK made EI mains powered smoke detectors... they also have a battery for when power is lost, and all the mains power supply seems to do is light up a green led constantly to give a quick confirmation that everything is still ok. They can be connected to each other as well via a wire, or optional radio mount plate. They are a fair bit more expensive though!

The IR LED would have been visible to the camera wouldn't it ? (Were the overhead lights too bright ?) Another interesting video, Thanks BigClive, mmmm8888888888888 !

My smart phone can detect infra-red radiation from TV remote controllers. Would that also work for the Led You removed. You should have turned the lights off to see if you camera picked anything up.

Is there a way to tell if a smoke alarm has an ionization or optical sensor just by looking inside the chamber? I recently got a smoke alarm for $5 but it has no mentions on which type of sensor it has, not even on it's owner's manual.

Have you checked out the LCD carbon monoxide detectors on ebay? They are $5.73 usd and claim to comply with EN50291 european standard. I have one by my furnace room. Hope it actually works...

1:10 "Let's just pop the battery in here and...... Aaarrrgghh, screw it, let's just rip it apart and see what's inside" 😂😂😂

does it still work after you changed the led

And it is still amazing, how sophisticated some of this really cheap devices are. As long as the Chinese stick to low voltage gadgets, I am fine buying them. Thanks for your great work, Clive! And it had to be said: You are a great engineer!

Hi sir.. I just bought 6 units of these exact smoke detectors.. i wonder if i could hook them all together by a wire to sync their alarm when triggered? Thanks

Actually, the best overall general purpose detectors will combine ionization with photoelectric detection as their individual strengths and weaknesses complement one another very nicely. As to which is superior depends heavily on the type of fire, hence the advantage of combining both technologies into a single smoke detector. Photoelectric is more sensitive to a smoky smoldering fire, either just getting started or that is burning poorly. However, ionization detectors respond best to a flaming fire, such as with an established or fast-moving fire or of a relatively clean burning flammable liquids/accelerant fire, which tend to give off much less smoke (where photoelectric then falls short). And in applications where neither is acceptable (high dust environments or lots of false positives) there is also the option of thermal fire detectors, but they are also often the slowest to react (typically looking for a ceiling temperature of 140F+, 60C+), unless more advanced types are used.

Both photoelectric and ionizing have their advantages… the best ones are the hybrids that are essentially two detectors in one package, one of each method. Best of both worlds

It seems like with this unit...you would need an awful amount of smoke to trigger this thing...given how you blew a large cloud of vaper into it and I'd imagine that even with a light amount of light being disrupted...it should go off...rather than a large plume of "smoke". Then again, it could be that way due to the fact that they're using a very out of date photo light sensing technology and they know it's crap, so they're doing all they can to avoid the thing randomly going off by any light possible. (Then again, a laser pointer normally tricks these things easily). If it was me, and the safety of my house and my loved ones was on the line...I would certainly not cheap out on a smoke detector...but something tells me that if they still manufacture this, it's because it sells...and that's a scary thought knowing that many people have this in their homes.

Only ever buy Photoelectric Smoke Alarms (for Bedrooms, Hallways and Common Rooms!) as they give you way more time to escape then Ionization Smoke Alarms also at least in the Kitchen and Garage use a Carbon Monoxide/Dioxide many newer ones can also sense Methane, Natural Gas and LPG/Propane also in a kitchen apart from the gas sensor use a Thermal Sensor Generally 3 to 5 metres away from direct line of sight of the stove or 1 to 3 metres if indirect (but not around the corner from the kitchen!). On a side not always use Surge Protectors on any electrical device even Power Board/Strips that have Surge Protection (as the resettable kind of surge protection take much more time and often have a higher capacity before they trip risking losing your devices!) and especially on Power Boards/Strips that have no Surge Protection of their own which should be illegal internationally. Never trust a Power Board/Strip that does not have an Earth Pin/Plug as if they do suffer a major surge like a lighting strike (As a rare but still very possible scenario!) they will set your house on fire and fry all connected devices even if you have them turned the devices off physically!

The fire dept here gives those away free if you go ask for them. The ionisation technology is when the device ionizes the air around the arcing before it sets your house on fire.

led pulling too much power causing voltage drop?, many smoke detectors are very fussy on voltage and a slight bit of drop will show low battery, annoyingly so. I wonder how long this would run with that cheap battery before its beeping in the middle of the night at you!

I got a question after I bought mine I accidentally dropped it on the concrete floor do you think anything is broken in there at all

Some informed comments here. These very simple, cheap alarms are a quick introduction to more complex units. Different standards operate for different places. One secured housing community had all smoke alarms powered and linked to a central monitoring place. Battery backup (9v battery) was provided. If the battery dropped in voltage, the unit forced open the battery container. This is what I noticed, so I replaced the battery. The central monitoring place should have noticed this too. Not sure why they did not.

Interesting video, sir! I honestly, snobbishly, expected this to be a danger to us all. Thank you for dispelling the myth.

He didn't explain the potentiometer! :( Looking at the datasheet, i'm assuming it has to do with the sensitivity of the detection? It seems to be hooked up with the IR Detector.

This may be a silly question, but do you actually vape or keep the bits around for giggles?

That is a pretty neat bit of kit

These cheap Chinese smoke detectors are so cheap because they use an active LED, where the "normal" ones use the radioactive decay of a small sample of Americium (about 0.2 micrograms). In the case of alpha decay from Americium, the ionized particles charge the air between two electrodes, which smoke will dilute. When the current is less than expected, it triggers the alarm. I imagine that the Chinese one might need it's battery changed a bit more often, though unlike the Americium model, doesn't have it's radioactive output fade over time, decreasing it's efficiency. About 3% of the Americium 241 (half life of 232.2 years) will have decayed into Neptunium 237 (half life of 2.14 million years) after about 19-20 years. This makes the Americium-type smoke detector less effective over time, even if the circuitry were to remain perfect. In America, they recommended that you replace your smoke alarms every 10 years. The question would then be, how reliable are the components in the Chinese LED smoke detectors? Given how cheaply the Chinese components tend to be made, I wouldn't bet on them having a greater lifetime than the Americium-type.

do you have a problem with solder-suckers or do you just not have one?

Hi Clive, may I ask how come you don't use a solder sucker instead of braid?

They got good piezo even lower voltages. I unsoldered it put it on a board.

Very interesting, clever design. Thanks!

Try to avoid the black background,please. The camera can't adjust the white bal and contrast when you flip the datasheet pages.

wow, i was really tired, and i somehow fell asleep i think around the beginning of this video, with my headphones on, no less! i did have quite an awful dream about being chased but i think the video must have been over by then. i rewatched it and had no recollection of hearing that beeping noise.

Looks the same or at least similar to the ones sold under the status name for around £5 in some shops in the uk

I`m on the edge of my sofa watching this . . . am I showing the first signs of madness?

Just FYI, you can see IR LED via cameras if you're viewing directly on, this may prevent you having to disassemble in the future :). (Unless of course your camera has an IR filter that is :P)

At least that actually works! I got an el-cheapo Chinese CO alarm from eBay to experiment with, which had a fake CO sensor cell, so it would never have gone off. (It triggered when I fitted a *real* CO sensor). I wonder how many homes those things are in flashing their little green LED making the owner think they're protected...

Sir, Can you please send me 12v smoke & fire alarm circuit drawing? Do you have any simple sensitive fire alarm circuit?

I just got this exact unit without packaging or a battery from china to USA for $2.49USD on eBay.

Ionization smoke detector...so is it legal to ship Americium by regular airmail?

Hey Clive, can you do a teardown of a carbon monoxide detector? I am curious to see what the mechanism of detection is.

What a lovely chip!

Clive, you need some proper solder wick! Get some Chemtronics 10-100L from your local supplier - You will thank me when you try it.

Good ones also include a switch to make them keep beeping if they detect.

Please enlighten me. What are the major issues with lead free solder?

Do you have anything on carbon monoxide detectors?

In America, smoke alarms are supposed to use a temporal code 3 alarm sound. So despite the price, this still probably wouldn’t be my first choice.

Incredible for two pounds. Great vid as always. Thanks.

Where was it made?

Cooking with gas... never trips the optical, but the ionization one is hairtrigger, even though it is much further away, and there is no smoke