Add a shutoff timer to your bathroom fan

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.

Christmas light controller

We get a lot of tips about Christmas light controllers but rarely do they contain the kind of juicy detail that [Vince Cappellano] included with his setup. His video explaining the controller he built is embedded after the break and it’s not to be missed.

We think there’s a lot of good design invovled in this porject. First off, he’s got eight physical channels, each with optisolation and a triac for 256 levels of power control. But he was able to double the control to sixteen virtual channels if you’re using LED lighting. That’s because on those strings half of the LEDs are reverse biased compared to the rest. By adding sensing circuitry to the incoming AC, he can switch the triacs to only send positive or negative voltage through the LED strands, which produces the additional virtual channels. And did we mention that he did all this using wire wrapping and point-to-point soldering?

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Waking up with the (fake) sun

[Bogdan] has some trouble getting up in the morning. A blaring alarm will do the trick but that’s no way to start the day. To get him through the dark winter months he wanted to try a sunrise simulator. He patched into the alarm signal of his bedside clock, intercepting the command from the clock’s microprocessor and using it as an input for his own ATtiny13. From there, the tiny13 gradually brightens a 150W halogen lamp using a triac until his room is as bright as a July morning. A signal is then sent to the alarm clock’s audio amplifier to turn on the audible alarm. He’s got the system set for a 20-minute sunrise so it’s just a matter of programming his alarm 20-minutes early than the ‘I absolutely have to get out of bed now’ time.

10,000 watt fluorescent array

This is an array of flourescent tubes that form a display. The video above is just two modules of a ten module installation that [Valentin] and his team are showing at an exhibition in Berlin tomorrow. The connected modules form something of a scrolling 16-segment display (similar to the 17 segment display modules of the ninja party badges but much larger). They’re using triacs, optocouplers, DMX, and an Arduino to interface a computer with the 182 fluorescent tubes of the display. Check out a second video after the break to see (or be blinded by) all ten modules pulling 10,000 watts.

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A remote controlled RGB light bulb lamp

RGB just got a lot brighter by using 3x60Watt flood lights instead of an LED. The bulbs are driven via TRIACs and the whole thing uses a remote control to change the levels of the three bulbs. It is also able to store these levels for later recall. The IR receiver was taken from a dead TV set along with its remote control, or a universal remote set to a Phillips TV can be used. The source code and schematic for this project are available.