Humble beginnings of a home automation project


This board is the start of [Steven Pearson’s] quest to automate his home. The module will be used to prototype the rest of the project. Right now it uses an ATmega328 chip running the Arduino bootloader. This connects to one mechanical relay which we would wager is mains rated. The module will be controlled wirelessly via the wireless module seen in the foreground. That is a nRF24L01 board which he chose because of it’s bargain basement price tag of around $1.50.

There is much room for expansion in the system. You can see that a light-dependent resistor has been added to some of the microcontroller’s breakout pins. We would guess that [Steven] will use the hardware to develop for many different functions and will design more task-specific modules as the project progresses.

If you’re a fan of PCB milling and population you won’t want to miss the video after the break. [Steve] posted a fast-motion video of the entire process.

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Turning 3D shutter glasses into automatic sunglasses

[Dino’s] hack this week seeks to create sunglasses that dim based on the intensity of ambient light. The thought is that this should give you the best light level even with changing brightness like when the sun goes behind a cloud or walking from inside to outside. He started with a pair of 3D shutter glasses. These have lenses that are each a liquid crystal pane. The glasses monitor an IR signal coming from a 3D TV, then alternately black out the lenses so that each eye is seeing a different frame of video to create the stereoscopic effect. In the video after the break he tears down the hardware and builds it back up with his own ambient light sensor circuit.

It only takes 6V to immediately darken one of the LCD panes. The interesting thing is that it takes a few seconds for them to become clear again. It turns out you need to bleed off the voltage in the pane using a resistor in order to have a fast response in both directions. Above you can see the light dependent resistor in the bridge of the frame that is used to trigger the panes. [Dino] shows at the end of his video that they work. But the main protective feature of sunglasses is that they filter out UV rays and he’s not sure if these have any ability to do that or not.

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Taking a moon light from grayscale to full color

[Terry Miller] picked up a moon light on the cheap. All it does is light up some white LEDs to simulate moon phases after sensing nightfall via an LDR. He figured he could do better and set out to replace the electronics with a more colorful offering.

He chose to use an ATmega328 because he already had it on hand. The chip drives a series of RGB LEDs in a multiplex arrangement. To protect the I/O pins (and drive the LEDs at their target current) he is using a set of high and low side MOSFETs. Rather than rely on the light sensor to switch on the lamp he decided to add an IR receiver. In the video after the break you can see that this lets him cycle through colors and effects, in addition to switching the lamp on and off with a remote control.

With the enclosure put back together he is still able to reprogram the chip thanks to a serial header included in the design. The device is battery operated and the life estimates are included in his write-up.

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Motion sensitive RGB lamp can standby for 3 years

Ooooh, nice enclosure! This is a little motion sensing lamp which [Krazatchu] built a few years back as a Mother’s Day gift. The PIR sensor is easy enough to see as the white dome on the front of the case. But look closely below that and you’ll see the LDR which it uses to keep the thing asleep during the day. This is intended to save on batteries but the original version still ate through them like crazy. This year he gutted it and worked out a much more power-friendly design.

He moved to a TLC1079 OpAmp which greatly reduced power consumption when reading from the PIR sensor. The microcontroller was also upgraded from an ATtiny13 to an ATmega328, making the new version Arduino compatible. It puts itself to sleep and keeps the lights out during the day, drawing just 0.08 mA. When driving the RGB LED the lamp pulls about 50 mA. That should still last a while on three AA batteries but we’d still recommend using rechargeables.

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Alarm clock wakes you like [Lawrence Welk]

That awful buzzing/beeping beside the bed in the morning might not seem so bad if it were a cascade of bubbles instead. At least that’s what [Will] is hoping for. He took a child’s toy and turned it into a bubble blowing alarm clock.

We’re guessing you’re not going to be too happy with the alarm settings feature. This isn’t using a real-time clock, or any clock at all really. [Will] rolled his own light detection circuit using a PNP transistor whose base is controlled by an LDR. When the light level in the room reaches a certain threshold the bubbles start streaming out of the front of this thing. He test the system in the video by switching a lamp on and off in a dark room.

Up at dawn has never been a way we could describe ourselves, but the one-wire control method seen here could easily be provided by a microcontroller rather than the LDR. Oh, and for those that don’t get it; the [Lawrence Welk] show always started with a screen full of bubbles.

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Light programming for a clock


So at first glance we were thinking there wasn’t much special about this clock. It’s based on an Arduino and displays the time using a character LCD screen. But then we realized that there’s no battery-backed RTC and no buttons. How the heck do you set the time on this thing? [Mossblaser] is using a light programmer to set the time using a computer screen.

We’ve tried nearly the same data transfer technique before, using a white and black flashing computer screen to push Manchester encoding to a light dependent resistor. We were met with limited success, but you can see that [Mossblaser’s] rig is much more reliable and we think there’s a few reasons behind this. First, he’s only sending five bits per seconds, a very slow speed when it comes to digital transmissions. This helps to make up for slow LCD screen refresh. Also, the LDR is surrounded by material on the back of the case that will help to block out ambient light. And finally, he’s using a smaller part of the screen instead of flashing the whole thing. This may result in more accurate timing. You’ve got to admit, this is pretty slick!

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Sun-powered Stirling engine with automatic tracking

Check out this solar-powered Stirling engine (translated). The build is part of a high school class and they packed in some really nice features. The first is the parabolic mirror which focuses the sun’s rays on the chamber of the engine. The heat is what makes it go, and the video after the breaks shows it doing just that.

But the concept behind the mirror makes for an interesting challenge. The light energy is focused at a narrow point. When the sun moves in the sky that point will no longer be at an efficient position to power the engine. This issue is solved by a pair of stepper motors which can reposition the dish. It’s done automatically by an Arduino Uno which makes readings from four LDR (photoresistors) in that cardboard tube mounted at the top of the dish. If the light intensity is the same for all four, then the tube is pointed at the sun. If not, the motors are tweaked to get the best angle possible.

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