[haqnmaq] admits that he suffers from Obsessive Compulsive Disorder and on occasion, can be found washing his hands up to 20 times an hour. Very distrustful of cloth towels, he exclusively uses paper towels to dry his hands, to the tune of 2-3 rolls a day. In an effort to lessen the impact his OCD has on the environment and his wallet, he decided to build an automated hot air hand dryer using a 555 timer, which doubles as his entry in the 555 Design Contest.

The concept behind his project is to use a hair dryer as a hot air source, relying on a phototransistor and a pair of IR LEDs to detect when hands are placed under the dryer. When a pair of hands are detected, a relay is triggered and the hair dryer is turned on. Once the dryer has run for a pre-determined but adjustable time, the relay is opened, and the hair dryer turns off.

It’s a pretty simple project, but one that is quite useful, whether you suffer from OCD or not. The only thing he might want to watch out for is the restricted air flow to the dryer, since it is mounted in a sealed plastic container – a few seconds with a hole saw should remedy the problem quite easily.

Want to see the hand dryer in action? Keep reading for a short video demonstration.

[Thanks Ryan]

[Brian] came up with an interesting PC cooling setup. He lives up north where it’s chilly in the winter. Using a bit of dryer ductwork and he was able to harness the outside air to cool his box. The system uses a window insert along with a dryer hood to suck in the outside air with a PC fan. We hope the air is adequately warmed, as it is exhausted into the room. Join us after the break for more pictures of his setup.

Below are the duct fitting he used. This includes a hood for outside, a damper which closes with gravity, some scotch brite pad to act as a filter, a flexible duct, and a quick connect.

The next three images show the construction of the window insert. The filter and hood are on the outside of the board, and the quick connect on the inside. Although [Brian] shows a damper in his parts image, we’re not sure where that is actually installed. We think it would be best for this damper to have a servo actuator, as gravity won’t be enough to keep the wind from forcing it open.

While waiting for his clothes to dry, our reader [xaio] decided to poke around and see how his building’s coin laundry system worked. It turned out to be ridiculously simple. All he needed to do was jumper the cable coming from each machine and they’d run without issue. We wonder why the relay box is so big. In any event, it could certainly benefit from a more secure installation.