Airwick fart neutraliser - with schematic

Seriously... This unit was supposed to be able to detect farts and then quench them with chemical aroma on demand. Well it did until I broke the sensor (not with a fart).
I'm not sure if these are still available in other countries, but they weren't on the shelves long here.
The circuitry is interesting, but bizarre. In hindsight I could have emulated the sensor with a variable resistor and seen how it affected the other circuitry, but as it is probably only switched on briefly at an unknown timing it would have taken a long time to catch it in the act. It may also test in very short time bursts, so without a data logger it would have been tricky.
The design of the circuitry is surprisingly complex and makes me wonder if they just squeezed the max out of a basic function chip to keep costs low.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- www.bigclive.com/coffee.htm
This also keeps the channel independent of KZbin's algorithm quirks, allowing it to be a bit more dangerous and naughty.
#ElectronicsCreators

[@rarbiart]

"triangular screw heads!" I like the exitement about getting into the off limits terrain.

[@purvel]

"*gasps* It's triangular ones, they don't want us in here!" edit: "...good!" :D

[@phils4634]

Triangular heads seem to be the current default for tamper-resistance. Used to be the tamper-proof Torx screws with the central pip.

[@markfergerson2145]

Reminds me of the old sating “No user-serviceable parts inside? I’ll be the judge of that!”

[@MadScientist267]

Flathead tweaker for the win on every "security" screw. I have a favorite that gets 95% of them first try. Great to have in the box.

[@samuelfellows6923]

And us DIYrs can buy triangular screwdrivers/bits and defeat the anti-tamper “screws” on many things 😁

[@BentusiProgenitors]

Only thing worse than a fart is a fart mixed with chemicals.

[@jrharbortproductions]

"Let's mask that fart with the smell of pine trees so now it smells like you took a sh*t in the woods"

[@mattcaldwell4727]

Generally, that's how I think about most "scented" things - air freshener, trash bags, dish detergent, car vents - none of this stuff needs a "scent" and it always smells worse than whatever the thing it's trying to cover up.

[@suspicionofdeceit]

Amen, scents, fragrances, perfumes, and incense are repulsive.

[@BromideBride]

@@mattcaldwell4727 when my washing machine died, my neighbour graciously washed a bag of clothes for me. Whatever they used left a smell so potent that I could not rinse it out and I ended up dumping the clothes in the charity shop collection bin and buying less polluted items from their rails. I literally could not have the smell in my home without gagging and gasping. And I worked as QC on a gel air freshener line until I discovered an allergic reaction to grapefruit extract (used in odour neutraliser gels) - at which point they terminated my contract and escorted me from the premises and the agency stopped offering me work like I'd just ID'd a radioactive leak. They probably did me a favour in the long run. Mind you, I could wear a shirt for a shift and it "freshened" the air for a fortnight if not washed immediately.

[@GothGuy885]

@@jrharbortproductions there was a comedian back in the 70's who had a record out, with a routine about someone who used his bathroom and really stunk it up and then they proceeded to use pine air fresher to try to cover it. the comedian went to use the bathroom after and said it smelled like someone crapped their Christmas tree. 🤣

[@thedownwardmachine]

What a relief to see this. I have a Hathaspace in the bedroom that reliably detects farts. Even under the covers, 30 seconds after the fart it auto increases fan speed. Until this video, I was half worried that there was a call center somewhere filled with people listening for farts.

[@fuller9x]

You need the IOT version for that. Then they can track when you have chilli

[@Netties8266]

My wife is excellent at detecting farts. One time she went out of control big time. I’d been out on the piss and accidentally had a wet fart. Her microchip was spot on in detection

[@Kae6502]

@@Netties8266 There's a whole circuit built into the female brain for that specific purpose lol :D

[@Tom-90210]

I must have the organic immediate notification upgraded unit. Even before sounds of digestion has passed the cheeks, it audibly states not to do it.

[@Conservator.]

@@Netties8266 Much too much info.

[@ragetist]

Somewhere there's a man named Arnie who has the honor of having a fart sensor named after him.

[@mysock351C]

And I hear his last name is Dutch and lived in the town of Ovens across the way in County Cork. While his passing may come at some point, his sensor will forever be immortalized with a subtle tones of such classics as winterberry ice, cherry blossoms and autumn apple picking.

[@stevebabiak6997]

His flatulence must have been potent to get that detector to bear his name ;)

[@3rdalbum]

Yeah, he's probably the guy in the air freshener office who has a reputation of gnarly farts.

[@johanea]

My wife is the absolute best fart detector there is.

[@theairstig9164]

Pregnant women have an incredible sense of smell

[@gary_rumain_you_peons]

She who smelt it, dealt it.

[@leestons]

@@gary_rumain_you_peons He who said the rhyme, did the crime.

[@gary_rumain_you_peons]

@@leestons She who denied it supplied it.

[@justfellover]

Is she busy the third Saturday in June? I'm planning an important event and the Airwick sensors aren't available anymore.

[@tonynicholson3328]

It takes a smart feller to understand a fart smeller device😅.

[@pomodorino1766]

You are a good joke teller Sir!

[@TheWellHungPony]

"Touched it provocatively..." This is why, as a person who is utterly confused every time you go into details about electronical bits, I love watching your videos. Stay awesome!

[@donerskine7935]

Triangular screw heads, Hard to break in to. Fart Knox , as it were. Presumably the neutraliser uses negative fartback.

[@Kae6502]

The minute you said you'd 'Drill It Out ' - it started turning. Brilliant. Just... brilliant.

[@Kae6502]

Note to self: Threatening fasteners with termiation may result in favorable results... Excellent!

[@DemolitionManDemolishes]

"Old man shouts at a -cloud- screw"

[@graemefenwick6925]

left-hand drills FTW

[@marcse7en]

Screws are sensitive, and they have feelings too!

[@curtishoffmann6956]

I got a dog because someone said they have a great sense of smell. Turned out all the farts were coming from the dog.

[@Retep4565]

Probably the dog ran a self-test routine periodically.

[@oldfatbastad6053]

dog farts are fucking rank

[@BedsitBob]

@@oldfatbastad6053 So are cat farts. 🤮

[@RicoElectrico]

​@@BedsitBobcat poop can be worse, literally tear inducing

[@PeterEdin]

😂😂😂😂😂😂 brilliant.

[@brettd5884]

At 7:10, you start talking about the strange arraignment of the 2 transistors. Those transistors, the diode, the 33 Ohm resistor and the 1k Ohm resistor from a current mirror. Or it might be a differential amplifier, as you might see inside an Op Amp. The 1K is pulled to 0V and acts as a constant current sink from the 2 bases. The transistor emitter on the left is held about 0.7V below Vbat, while the base-emitter junction has it’s own 0.7V drop. That base is about 1.4V below Vbat. The base of the other transistor is at the same voltage, so it’s emitter is also about Vbat-0.7V, leaving 0.7V across the 33 Ohm resistor. 0.7V/33Ohms = 21mA. That regulated current is provided to the sensor heater, making it a constant power heater. For this to work, the 1k needs to be grounded by the MCU, and might be tied to the right transistor collector. The sensor output is resistive (100k-500k), according to the datasheet pointed to by moe.m. If one side of that sensor is tied to the transisitor-1M resistor (top right corner, page 2), it might form a voltage divider that could be measure by the MCU (that’s a pretty high impedance, and an ADC would have a difficult time acquiring a measurable signal.) Why the transistor? I’m guessing the sensor resistance and a hidden capacitance form an RC circuit with a discharge time that can be measured. The capacitance is charged by the transistor before the measurement, then turned off to begin the measurement. The time required for the capacitor to discharge to some voltage is measured. (I’m not really seeing how the sensor works with one of its connections open….) The ceramic resonator would be necessary for a stable time measurement, otherwise the MCU would have used an internal RC oscillator as an unstable clock source.

[@kimsleep4111]

that was my immediate thought as well

[@kyoudaiken]

So the blob chip on board just contains the secret formula of what to so with that signal.

[@kimsleep4111]

@@kyoudaiken it may just be a super powerful anti fart chemical

[@BromideBride]

You see, this is why I love this channel. Regardless of the mystery, there's always someone in the comments who fills in the gaps that Clive has to guess at. Tbh I'm still less than enlightened as I'm only a little more than a "battery & bulb" sort of person, but the veil is lifting at the edges and I look at circuits with keener eyes than I used to. I'm even switching leds with transistors and just ordered enough to launch a Saturn V after I ran out of salvaged parts. Come sunset my home becomes a photonic haven.

[@R50_J0]

I had a wall mounted flammable gas and carbon monoxide detector a decade ago. One day I was walking by the unit and passed a lot of wind. About 30 seconds later the shrieking alarm sounded and the LED display on the unit flashed “GAS”. Took me a minute to understand why. The wife came from the upstairs to see what the problem was. I explained that farts contain methane, methane is a flammable hydrocarbon gas, and the gas sensor in the detector treated it the same as utility gas. We laughed almost to the point of falling to the carpet. Good times.

[@nicksystermann1558]

Fun fact, not all humans produce Methane. Congratulations, you are one who does!

[@samuelfellows6923]

🫢

[@bigclivedotcom]

I farted into a fake CO2 (VOC) detector and it went off the scale.

[@nicksystermann1558]

Thats because "C02 detector" sells way more product than "flatulence detection gadget," sadly.

[@MarkGovier]

They use the transistor as a diode so it has the same temperature coefficient. It's a fairly stable current source for the heater.

[@MaxPivovarov]

the three transistors in middle is a current mirror with current control, the one use as a diode is a temperature compensation.

[@haideral5104]

The german magazine "Heise" wrote a report on how to salvage the sensor and how to connect it to an Arduino and that was back in 2014.

[@patchvonbraun]

I bought my first CO/CH4 detector for the house years ago. Decided I'll plug it in initially in the kitchen to test it out. My cat (dearly departed Da Vinci) decided to investigate it, then just sat under it the for longest time, and, well, farted. The detector went off promptly, causing him to leave most hastily. A good time was had by all.....

[@twentyrothmans7308]

I knew you'd break the fart neutralizer. One way or another.

[@Retep4565]

It's more like a fart obfuscator; it just covers up one smell with another.

[@twentyrothmans7308]

@@Retep4565 You're absolutely right. The best way around it is to have a household pet nearby, and adept anal ventriloquism.

[@user-pf3ye6yi9n]

@@Retep4565 The problem with the manual ones too. You don't walk into the kharzi and think "How nice it smells of flowers in here", you think "Somebody's had to hit the fart extinguisher, must have been really rank". And you know that stuff is still floating around in there under cover of the perfumed cloud.

[@Retep4565]

@@user-pf3ye6yi9n when you smell the scent of roses you know there's shit in the air.

[@MM.]

The slide switch with flowers in increasing size is a nice little touch.

[@Mike-H_UK]

Clive is about to fart but not yet..... One moment please!

[@willrobertson7778]

Hous of Commons might be a potential application...

[@stinchjack]

that may need a 'hot air extractor' also

[@brendan3603]

This is awesome. I still glazed over when i saw the circuit diagram but that’s because its late. I’ve never seen someone bust it out with the big zooms and diagrams.

[@KeritechElectronics]

Arnie? No problemo, it'll be back. Interesting device. 10/10, would test.

[@draketungsten74]

It detects Arnold Schwartzenegger

[@user-pf3ye6yi9n]

So this thing if you drop a bad enough one panics and shuts down. As Carsten from the Kempinger channel would say, "Very Satisfying" I always wanted to replace the can in those hotel room auto air fresheners with fart spray but I figured they would know who had the room last. The letter banning me from their hotels would probably have been worth it though.

[@jimsvideos7201]

I had one like this but it was telepathic. It makes scents when you think about it.

[@quantumleap359]

Boooo!🙄

[@jimsvideos7201]

@@quantumleap359 You're welcome!

[@MysteryD]

Funny story. My wife bought a natural gas alarm for in the kitchen, since we have gas appliances. It was constantly going off. We couldn't figure out why. Turns out, farts and hand sanitizer both set it off.

[@neontime]

The oddly connected transistors form a constant current supply for the heater of about 18mA. The IC can urn this on and off, and can also sense when the heater is actually drawing 18ma. If the resistance goes up to a level where there is not enough voltage to cause 18ma to flow, or a low battery does the same, the sense output (collector) goes low, otherwise it's high. I'm not sure why you would want to do that, but thats what it does.

[@davadoff]

Brilliant, thanks Why? I guess to go into power save mode and flash a LED to indicate the batteries need changing (to prevent over discharge of batteries; and prevent the end user being unaware the device has stopped working or thinking it is broken when it just needs new batteries).

[@Silverfoxwolfen]

It's... unusual to say the least. I wonder how it would deal with a triple fart?

[@zh84]

That's why the triangular screw heads.

[@TheCormTube]

"Not like an old lady making my house stink of chemicals" My Dad is insulted....he has two of these (without the smell sensor) on the go....

[@tncorgi92]

Thanks for the video, I am having neck surgery done on Monday and it will be a great time to go back and watch your videos, device builds especially. I only wish they would allow me a Dark & Stormy in the hospital! Though it probably wouldn't go along with the pain meds. 🥴

[@GothGuy885]

if you drink enough Dark and Stormies, you wont need any pain meds 🥴 😆

[@bigclivedotcom]

Here's a sneaky link to a recent unreleased video that will help you relax for over 2 hours. Save it for after surgery. kzbin.info/www/bejne/rXXXnIOsrpt7rZI

[@kimsleep4111]

Fart on it to test!!...FART ON IT!!!...... we shall watch!

[@radiotowers1159]

Really you dont want big clive to Fart, after Guinness it would probably blow your speakers

[@Youtubecensoredmyusername]

After the toilet bowl light, wouldn’t be surprised if Clive humored you, you seem very excited about it lol

[@inse001]

@@radiotowers1159Attention please, cover your ears.

[@bigclivedotcom]

Maybe that's how I broke it in the first place.

[@Youtubecensoredmyusername]

@@bigclivedotcom broken just means it has lost your interest

[@markedis5902]

The air freshener industry is the best example of generate a problem and sell a solution. Air not fresh enough? Open a window.

[@daleholten3012]

What if you are somewhere where you cannot open a window, or maybe somewhere where its freezing temperatures outside, or hot.

[@jjab99]

Great and interesting video as always, many thanks Clive.

[@grantrennie]

Thanks for another great video Clive 👍

[@pedroferreira4134]

It surely took a long time to reverse engineer. You do it so we don't have to do it. Thanks! A lot!

[@BedsitBob]

"Let's just chop some wires. Chop - Chop." I'm going to hazard a guess, you were never part of an EOD unit. 😁

[@TeriWilde]

😁👍

[@RT-qd8yl]

He doesn't look nearly hungover enough to be EOD, and I see no cigarettes. And I think he still has some hopes and dreams that are still partially alive 😄

[@bigclivedotcom]

Ironically, searching electrical cabins for explosive devices is one of my work duties on a particular military contract.

[@StephenBelcher-sr3zk]

I’m Out Clive: Thankyou Very Much Clive, Happy Weekend Man❤

[@MS-Patriot2]

Did the fart detector assist you 😉

[@sockcutter]

I take the existence of this device as a personal attack. My lawyer has been notified.

[@nat7278]

I like the way your diagram looks. Looks like a control room with a mysterious power panel. Would look cool on a t shirt 👕

[@memejeff]

Ok, this is a very interesting device. Very nice device. Quite surprised by the complexity of its circuitry. I hope you keep the PCB. Might be able to find a replacement sensor. You may also be able to decap it in the future.

[@elmonte5lim]

I could have done with one of these back in the eighties, when I had a Doberman, although - in fairness - it would have been like trying to neutralise a chemical attack. Bloody Bonios! Other than that, one couldn't wish for a better companion.

[@stepannovotny4291]

The transistor pair is a constant current source. The collector of the second transistor provides a low battery warning when the current source can no longer keep up. The epoxy chip is clearly an MCU. The "charge pump" is NOT, but rather an interrupt generator that wakes up the CPU every few seconds, to take a reading. The sensor is on the back and its wires are sealed to prevent perfume from poisoning it.

[@joeschmo622]

Those 3 transistors sound like they're hooked up as a current mirror to put 18mA through the heater, regardless of the applied voltage, ie, acting as a cheep 18mA current regulator. Keeps current constant at 18mA from fresh 4.5V new cells through end-of-life last-gasp moribund cells.

[@martinphillips7221]

The youtube commercial algorithm pulled up a trump pun running an old spice add on a fart detector video ,someone has a sense of humor

[@dr_jaymz]

The transistor arrangement looks like a long tailed pair. It's a current mirror. So it's providing constant current to the heater.

[@johnkey1682]

The shorted transistor/diode could be being used as a temperature sensor.

[@ShadowzGSD]

Love the way this video is right next to a Jack Vale Pooter video in my subscriptions feed.

[@phils4634]

If you wanted to, you can buy modular VOC sensors from the usual suppliers, for only a few dollars. I note you can buy combination laser dust sensors and VOC detectors for less than $8 too, in case you need both functions!

[@mstrawn69]

Just after the turb of the century, I was living and working in Denmark and I noticed that when you went to the bathroom and turned on the light, the fan didn't start unless you were dropping a deuce or taking a shower. If you just went in to take a leak, it didn't go on. I thought the Dane's had come up with some sort of fart sensing technology. Then I realized that it was just a timer.

[@tennicktenstyl]

I bought some gas sensors a while back to build a fart detector device. Turns out they are very sensitive to a very broad range of gasses, meaning that such a sensor would react to practically any bit of organic chemistry being present in the air, without differentiating beween cologne or fart

[@user-xh9pt8zu2l]

Very topical. Based on current USA NY court reports one of these devices might have beneficial application near the defendant's chair. 😜

[@JanaBuvari]

I like how you referred to my farts as 'Aromas' Clive, I'm flattered

[@bhambhole]

Finally, a device that can detect who dealt it.

[@chronicfatigue5416]

I like all of the test points on it. Like you'd pay to have it fixed instead of buying a new one.

[@markboldyrev8321]

I suggest sending the board to the dude who runs @electronupdate, he might be willing to decapsulate the chip. And regarding the weird charge pump arrangement, I'd speculate that they've shoe-horned an existing chip design and made some workaround circuitry to emulate the feedback signals that it expects to be seeing from what it is normally supposed to control.

[@BersekViking]

It's not odd. It's a current mirror configuration. The diode is a reference and the circuit keeps the voltage over the 33 ohm resistor to the same voltage as the diode voltage drop, thus feed a constant current to the sensor heater.

[@martinjf467]

Fart neutralisers, farting Ninjas… I’m beginning to detect a pattern here Clive! Could it have anything to do with deep fried Mars Bars and 60 shilling perchance? 😂

[@JessicaFEREM]

Honestly would be pretty awesome to put into a multitude of things, like a bathroom or kitchen extraction fan "you will not get away with stinking up the bathroom this time"

[@IronLungProductionsOfficial]

good morning From Australia Clive! :D

[@mddawson1]

If you get it working again, I believe this is desperately needed by Juan Merchan in New York.

[@ZeedijkMike]

The "wired" transistor pair could look a little like a digital controled constant current source. I could imagine the tempeature of the heater have to be quite constant.

[@bigclivedotcom]

I did ponder if it was being used as a current source, but wasn't sure if that could work.

[@anjkovo2138]

If that thing was in my bedroom it would switch on contantly until the battery runs out 😂😂

[@LawpickingLocksmith]

Interesting, I was thinking at one stage to build such a device. With one pad never been soldered I think you should re wire this unit just for the sake of it. As always brilliant reverse engineering!

[@johnwest7993]

We have a courtroom in Washington DC that could really use about 6 of those.

[@JurassicJenkins]

2:05 I thought for sure you were going to say “because I don’t fart” 💨

[@Mariazellerbahn]

What needs to be made is a fart clap-o-meter. Giving marks out of ten for potency.

[@grayrabbit2211]

I have Winix air cleaners at my home and they also are quite good at detecting farts. The indicator goes from blue (normal) to yellow (caution) to red (danger!), and the fan speed increases based on the level of stank. If you fart in my house, EVERYONE will be fully aware.

[@bashchelik100]

i didnt fart,you are...

[@mhammmmagh1465]

fart sensors? 🤣 great video doc

[@ChipGuy]

I have seen that weird arrangement for the heater transistors. The heating element has PTC characteristics and once it is heated up the voltage on the 33 Ohm resistor drops to a point that the other transistor with the diode does not conduct anymore. This tells the controller that the work temperature has been reached.

[@fromgermany271]

Expect the price to hike as there is upcoming demand from NYC courtrooms. 😂

[@tncorgi92]

Make America Stink Again.

[@misterhat5823]

Those aren't farts. They're full on pooped diapers.

[@trueriver1950]

Yes, indeed: there's a reason he's called Trump. The Americans just don't see how appropriate his name is, especially the MAGAfans.

[@goosedeathable]

@fromgermany271, because the corrupt ny legal system, judges and prosecutors realize it’s obviously a politically motivated trial to the general public?

[@stevebabiak6997]

I checked my calendar, it’s not April 1, so this must be a real device ;)

[@aviandragon1390]

Clive, I believe that set of three transistors is a PNP variant of the Wilson current mirror. Sorry if someone else already said this. I'm not going to read every comment.

[@jesuschal3802]

"...not like an old lady making her house absolutely stink of chemicals". Wow, I didn't know you knew my mum. Gosh, I've told her thousand times. Let's see now when I tell her that even Clive agrees.

[@zippy5131]

My dear good fellow, how many of us mere mortals utter the words 'One moment please' I think that would make a great T-shirt.

[@jerrydurand4127]

I think the odd transistors on the heater is so the processor can control the temperature. Heater resistance changes with temperature, changing the current draw. The processor detects the threshold and bit bangs the heater power. Maybe?

[@nickcliff]

Dog fart detected fleshing air 😂

[@alunjones3860]

The arrangement of parallel and series RC circuits to the left of the IC appears to be a band-pass filter, possibly a Wein bridge oscillator.

[@campermike8879]

Here in the USA I only recall the ones that went off at the time you selected

[@midinotes]

Kind of crazy the amount of technology being put into an air freshener! I know these companies keep trying to come up with new ideas to sell more air fresheners (although they don't actually freshen the air, they just cover over any existing bad smells). If it works though a nasty niff detector makes good sense as it would save on liquid used.

[@kyoudaiken]

It could be interesting to see waveforms and measurements from this circuit.

[@alangilchrist7864]

The transistor with the base tied to the collector - I think that configuration is sometimes used as a temperature sensor. So maybe it shuts off the heater if it gets too hot?

[@a-k-jun-1]

Well as an American over half a century old, I've never seen or heard of one of those before.

[@gordonlawrence1448]

I could be wromg but if I remember correctly therewere some cheap for the time cut down 8051s. They were slow CMOS only pulled down and at most had two ports. Usually no UART or anything like that. ATmel did some re0ebgineering and turned them intoa 20 pin DIP which you can still get from Microchip. It was the 90's when I did a few weeks work on these so take that with more than a pinch of salt.

[@bigclivedotcom]

The classic 8051 core is often found in generic Chinese microcontrollers.

[@wisher21uk]

Clive have you ever thought of going into marketing and advertising, you will be brilliant 😊

[@stuartmcconnachie]

Does it also detect old farts? Because if it does I’m doubly screwed.

[@phonotical]

It's nice they had the capacitor on the motor, as though the two seconds it's on for would make a world of difference... This seemed needlessly complex, the whole thing could be replaced with a 555 and a transistor

[@wemme]

There are a handful of mcus with intergated opamps and comparators

[@someguy2741]

We had a line of commercials for years here. "The house smells like fish!" "Now it smells like fish and roses!" I suggest you load the sprayer with fart spray and then leave it in a inconspicuous corner of Ralphies house. He wont complain about the house smelling like something and something worse if you choose something awful. I should be a counsellor.

[@leeroberts1192]

I saw a clip on KZbin once, of an office fart spray prank. There was a series of rooms in an office. In one room there was an extraction vent with a switch for a fan. The person would spray a little fart spray into the vent and turn the fan on for a few seconds before returning to heir desk. In a meeting room a couple of rooms along, they'd get the benefit of it. Every so often he'd spray air freshener instead. Can't find the clip anymore so I'm assuming it's been deleted.

[@andymouse]

That first page of transistors had 'current mirror' or part of a 'differential input' written all over it, it looks like the front end of an instrumentation amplifier which would make sense to me as your not dealing with nice clean large signals and I don't believe there is a Glaswegian Kiss approach and it's going to be a bit more involved. It's all pretty specific so shame they never label blob chips

[@fuller9x]

I would have imagined that the aroma of of punctured lithium batteries and aerosolized woofle would be more than sufficient for the bothy.

[@atkelar]

The 2-transistor circuit to me almost looks like a switched current source? I'm still behind on my transistor circuitry but the B-E drop is basically constant, i.e. the same left and right. The diode on the right makes for a very specific base voltage, let's say "Ub - 1.2V" and that puts the 33 across the same voltage as the diode, i.e. we know that the current across the left transistor should be 0.6/33 = 18mA and that would also be the current throught the heater... at least that looks like it. The input on the other collector might be a sensing input to detect a failure in the circuit? Or I might be completely off...

[@lichtbewolkt]

This thing was perfect, I've had them in my bathrooms years ago. Too bad they stopped selling the refills.

[@midbc1midbc199]

This deodorizer would have been working non stop if this was around during the Kenny VS Spenny farthing episode

[@onewiththefreaks3664]

Maybe a certain NY court might be very interested in this product.🤷‍♀

[@gorak9000]

Watching this on the ol' fart throne seems very appropriate...

[@cuteraptor42]

Nobody needs an airwick freshener when you have your special woofle aroma for masking the lead solder smell

[@adzib1823]

Is the transistor heater circuit shenanigans used to detect once the element is up to temp? Low resistance when cold = high current = 'output' high and then the output goes low once heated and passing a lower current? Kinda like an ultra-optimised 'transimpedance comparator'?

[@arva1kes]

I'm super interested in fart detection as i have been thinking to have "bad odor" automatic aromatizer thing for years now. I dont like it to be all flowers all the time. Just then bad dump has been taken.

[@fixitmakeit72]

Hi Clive, is there a module with microwave sensor I can use to trigger my action camera to start recording and also trigger off when the module times out or no motion detected? I would like to solder 2 wires to the camera switch and conect them to the sensor so when motion is detected the trigger will replicate me pushing the start recording button momentarily and the same when motion is not detected to again stop recording. Thanks Clive. Olly.

[@bigclivedotcom]

Not so easy. The hunting or trail cameras have the PIR built in.

[@trevorhaddox6884]

It seems to work like old school DVM/DMMs that used a pulse counter and a VCO.

[@MandrakeFernflower]

I wonder if it could get stuck in a loop since the VOC sensor cannot tell the VOCs from perfume and farts apart - it just reports the estimated PPM level of VOCs to the blob microcontroller