Add A Shutoff Timer To Your Bathroom Fan

March 19, 2011 by Mike Szczys 17 Comments

Adding this board (translated) to your bathroom fan will turn it into a smart device. It’s designed to automatically shut off the fan after it’s had some time to clear humidity from the room. It replaces the wall switch which normally controls these fans by converting the fan connection to always be connected to mains. The board draws constant power to keep the ATtiny13 running via a half-wave rectification circuit. A single LED that rises from the center of the PCB lights up to signal that the fan is in operation, but it is also used as a light sensor, similar to the LED communications hack from a couple of days ago. When the lights go on in the bathroom the microcontroller will turn on the exhaust fan via a Triac. It will remain on until the light level in the bathroom drops.

There’s an interesting timing algorithm that delays the fan startup, and varies the amount of time it will stay on in the dark depending on how long the bathroom lights were on. This way, a longer shower (which will build up more humidity) will cause the fan to remain on for the base of five minutes, plus one minute longer for every two minutes the bathroom was in use. Pretty smart, and quite useful if your bathroom sees high traffic from several family members.

LEGO Hand Controller

June 12, 2010 by Mike Szczys 12 Comments

[David Hyman] built this device to control a LEGO claw. One one end of things is the part you wear, that measures movement of two fingers and your thumb. On the other end of things is a LEGO claw with three opposing digits. You move, it moves. The claw uses light sensors and a gradient strip for position feedback. There is also an up-down wrist action that uses a touch sensor as the input. This is impressive enough to give the sniper rifle a run for its money.

[via Make]

Know Your Resistors… Tell The Time

January 15, 2010 by Mike Szczys 32 Comments

[Darren] built a clock that uses a resistor to display the time. Well, it really uses a model of a resistor. This extremely tardy entry in the Hackaday design challenge houses all of the electronics on a PCB the size of a business card. Four RGB LEDs shine up through holes in the wooden base to light bands on an acrylic tube. The colors correspond to the values used in the Resistor Color Code. In the picture above the clock is displaying 5:26 (that’s supposed to be a red band but the camera didn’t pick it up too well). The band in the center fades up over 60 seconds to signify AM, and down to show PM.

It may be late, but it’s a clever design. It looks sleek and it uses no buttons for an interface. [Darren] sourced the LEDs themselves as light sensors to display the date, and enter time setting mode.

Advent Wreath From Parts You Have On Hand

December 20, 2009 by Mike Szczys 9 Comments

Here’s an advent wreath made from six parts and a paper clip. Powered by a CR2032 3v button cell, the circuit has been free-formed using a paper clip as the conductor. We love the “dead bug” style of construction used with the ATtiny13 microcontroller because it adds an extra level of intrigue for the uninitiated. This project build on the flickering circuit we saw last year and uses the LEDs as light sensors, only turning on when a certain darkness level has been reached.

We used a tiny13 with our Menorah project last year and still have some lying around that we can use for this. We’re sure you’ve got at least a couple of low-pin-count micros on hand. If you don’t, you should!