Bathroom fan that switches itself on when it gets steamy or smelly

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.

Continue reading “Bathroom fan that switches itself on when it gets steamy or smelly”

Engine Hacks – A DIY Methane Generator

All “methane generator” jokes aside, This one actually serves a useful purpose. Although not an engine hack per se, methane can be used to run an engine. As the traditional method of powering an internal combustion engine, gasoline, gets more and more expensive, alternatives will have to be found. If you happen to live on a farm, or have access to a source of organic waste, this method could serve as a viable one.

One would need quite a bit of waste, as each kilogram yields around 400 liters of methane gas. This amount is enough to run a gas light for around 4 hours. Any sort of useful engine would require quite a bit more than this (chicken farm possibly?).

A process for converting waste to fuel is illustrated in the video after the break. Extreme caution should be used if attempting to do something like this. There is a danger of not only flammable gas leaking and catching on fire or exploding, but the organic material can be quite toxic as well. Continue reading “Engine Hacks – A DIY Methane Generator”

Composting to create hot water

Want nature to supply you with 130-150 degree hot water? [Onestraw] shows you how to get just that by building a compost heap that heats water. Finding himself the proud owner of a dump truck of green wood chips [Onestraw] went about building his own version of Jean Pain’s thermal compost pile. The idea is to produce and store methane generated from the compost pile but in order to do so, the temperature must be kept fairly low. The microorganisms in the compost generate a lot of heat trying to break down that matter and running water through the system will keep the temperature low enough for the methane-producers to be happy. The side effect of this cooling system is hot water coming out the other end. [Onestraw] even has plans to use salvaged car radiators to turn the hot water into a heating system for his home. Granted you’re not going to add this to your apartment, but if you have space and waste plant matter and need hot water this is a great way to get it.

[Thanks Joel]

Twittering toots, a chair’s perspective


We might have to add a category of “stuff made to twitter”. The latest installment is an office chair that twitters whenever it gets farted on. The author has a smart sounding description as to why he decided to make this, and he has a pretty good point about twittering interrupting the things you’re twittering about, but it all boils down to the fact that he wants to twitter his farts. We can’t say that we didn’t expect something along these lines. He has mounted a natural gas sensor in his chair, along with a squidbee wireless transceiver. You can download all the code as well as see the construction in the instructable. You can also follow his flatulent adventures on the twitter account of the office chair.