At first we thought that [Brandon Dunson] was writing in to tell us he’s too lazy to fix his bathroom fan. What he really meant is that simply replacing the unit isn’t nearly enough fun. Instead, he developed his own bathroom fan trigger based on stinky or humid air conditions. He didn’t publish a post about the project but we’ve got his entire gallery of build images after the break.
The initial inspiration for the project came from a twitter-connected fart sensing office chair. Hiding behind the character display you can see the MQ-4 methane gas sensor which he picked up for the project. But since there’s also a shower in the bathroom he included a humidity sensor with the project. Both are monitored by an ATmega328 which averages 10 readings from each sensor before comparing the data with a set threshold. If the sensors read above this level a relay turns on the bathroom fan.
Don’t be confused by the small DC fans seen above; [Brandon] is still using a proper exhaust fan. These are just used to help circulate the air around the sensors so that low-hanging smells will still trigger the system. This has got to be the perfect thing for a heavily used restroom.
He jacked my idea!
I’ve actually wanted to figure out if it’s practical to put a couple very thin intake vents under the hinge end of the toilet seat itself, with a variable speed exhaust fan. Keep it on very slow to pull air into the system and sense methane, and go full speed when it does. Capture things at the source….
So why not just keep the exhaust turned on all the time whilst you are seating on the toilet? — and then just turn off automatically when you stand up. So methane or not, smelly or not. it will vent out the gases.
I’m not sure if/why my earlier reply didn’t display so I’m re-replying,
Google has shown me 2 different ways to vent toilet odors near the source…
http://www.jonevac.com/
http://vented-toilet.com
Not only is this the shit, it also smells it! Maybe he should consider attaching an automatic air freshener to the system, well for methane anyway.
Actually, people can’t smell methane (which is why they add sulfur-based compounds to natural gas). The smell of flatulence comes from hydrogen sulfide and other odorous items our body produces.
About the hack, because I don’t have a bathroom fan, I was thinking of making a wood frame, mount some computer fans, and add a timer. When someone leaves the bathroom after a shower or crapping, press 5 or 10 min and the fan will do its job, exhausting out the window like a small window fan. Now I like the idea of using a moisture sensor so I can prevent mold from building up in the shower!
They actually make light switches with a built in timer that fit in a proper wall quad box. Pretty neat and not too pricey…
https://www.amazon.com/Century-Countdown-5-15-30-60mins-2-4hours-Required/dp/B0184PH9TM/ref=sr_1_34_sspa?ie=UTF8&qid=1539484646&sr=8-34-spons&keywords=wall+switch+with+timer&psc=1
Main problem I see is that not all people produce methane.
That’s what I’ve been wondering re: above… How *can* you reliably sense, uh, scents? One thought was to simply include a pressure switch under the seat “feet” along with the intake vents – sit down and it triggers. Detecting the actual airborne compounds might be harder than just a methane sensor.
Maybe it doesn’t detect the “scent”, but rather the farting sound you make? LOL
Sensor: Oop, that’s one loud fart you got there, lemme turn on the fans..
OVERLOAD OVERLOAD OVERLOAD CRITICAL SYSTEM FAILURE
Maybe a piezo sensor glued to the underside of the toilet seat to detect the unique vibrations of flatulence? OB: connected to an Arduino of course!
Hack a Day already covered a “odor sensor teardown”: http://hackaday.com/2011/09/21/air-wick-odor-detect-teardown/
Frankly speaking, I’m not sure a VOC sensor will lovely do its job with crap, farts and sweaty balls smell, but they sell them almost with that purpouse, so there’d be something true, somewhere (over the rainbow)
omegacs
There is a commercial product that is an exhaust fan that fits on the tank and under the lid. Draws gas out through the overflow tube. Usually wired to be on when the light is on.
Is an MQ-4 sensor rated for humid environments ?
I think the sensor will be ruined in a day or two.
His methane sensor will be bugered within a week. almost all Gas sensors are damaged by high humidity… Sounds like someone did not read all his data sheets.
At a backpacker’s hostel I once stayed at in Los Angeles the ensuite exhaust fan came on as soon as you turned on the light, and stayed on for about five minutes after you turned the light off. That seemed to work pretty well.
Can I recommend amazon.com instead of hackaday? I’m sure they sell commercial versions or equivalents of most things on this site, which seems to be more your taste.
I’m not saying this couldn’t involve an arduino, or that it couldn’t be somehow connected to twitter.
Man, this guy is amazing! Come put one in my husband’s bathroom!
this is great! was wanting to build something like this for my cats litter box. now I just have to vent it outside…
Only about 1/3 of humans produce methane in their colon. Almost all of us produce hydrogen sulfide. Should use a detector for that instead of methane.
BTW, only the methane farters can light theirs on fire.
What do the other two thirds of us fart?
I know lots of circuits have brownout detectors, but this is ridiculous. :D
Why has this not gotten a +1 yet?
New product: a fart detector that drives a wave player with laughs and/or cheering crowd sounds :)
Just wire fan to bathroom light = done.
This may very well be the best hack ever devised.
Just a stream of photos with no information? This is neat, but I was hoping for more.
Very nice idea! This inspired me to replace a failing bathroom fan with a computer fan. I’d been looking for and not finding the right size standard 110volt fan. This made me realize I could install a 12 volt adapter and a computer fan instead. It’s not automatic yet, but the humidity sensor and controller are on the way from Adafruit.com
There are already light switches with built-in timers on the market if all you want to do is run a particular home device for a specific amount of time.
something like this: https://www.amazon.com/Century-Countdown-5-15-30-60mins-2-4hours-Required/dp/B0184PH9TM/ref=sr_1_34_sspa?ie=UTF8&qid=1539484646&sr=8-34-spons&keywords=wall+switch+with+timer&psc=1
The fun part about this though: I’ve been considering building a dog bed for our Husky that serves 2 purposes: one to give him a cool spot to lay on, and another to get rid of farts when he passes gas. Its bad enough he wakes up my fiancé when he sleeps under the window (her side of the bed).
Figure if I can run a carbon filter between the fans and the intake port of the dog bed frame, and I can trigger the bed based on temperature or smell, I’m golden.