As one of the founders of Netscape and the Mozilla Project, [Jamie Zawinski] is no stranger to frustration elicited from syntax errors, terrible implementations, and things that don’t work even though they should. This familiarity of frustration is what makes [jwz]‘s command line controlled curtains so great; it’s rare to see someone so technically proficient freaking out over the lack of DHCP on an Arduino Ethernet.

[Jamie]‘s project begins as so many do – modifying an existing piece of hardware to connect to the Internet. This is easier said than done, as [Jamie] fried a USB hub, FTDI cable and an Arduino Ethernet all at the same time. Finally turned onto the seeed relay shield, [jwz] got busy writing scripts to power his curtain.

Of course, this level of automation is nothing without a good bit of integration. After [Jamie] realized his projector (a Panasonic PT-D5500U) and receiver (Denon AVR-2805) could talk to his computer, he got busy mashing them together with a Griffin PowerMate. Mashing the button on the PowerMate turns on the projector and closes the drapes. There’s also a cron job running so that [Jamie] is reminded of the glowing orange ball in the sky.

The headlight enclosures on [Bill Porter's] 2004 Passat had yellowed with age and were not outputting the kind of light they should. He decided to replace them with some aftermarket modules that also incorporated LED strips. When they arrived he was surprised at how easy there were to drop into place. But when testing he was certainly not satisfied with how they worked. The day-driving mode used the HID bulbs at full power, where the factory assembly had dimmed them during the day. He set out to alter the electronics to work as he prefers.

Always the mad scientist, [Bill] started off by making a truth table showing how the lights reacted to the various states of the ignition and headlight switches. What he came up with is an AND gate built from a relay and diode. It allows him to have the LEDs on as the running lights (without the HIDs on at all), and leaves the rest of the functionality unaffected.

[Andrew] shows us one way to reuse all those strands of Christmas lights you used for decoration this year. He had a friend that was helping with stage props for a local musical and ended up using his skills to build a lighted sign with some animation capabilities.

The original plan was to cut out letters for a sign by hand and ring them with white Christmas lights. It is possible to hand cut parts reasonably well, but [Andrew] knew he could get a much better result in less time using a CNC ShopBot to make them. He didn’t know the spacing for the lights so waited and drilled holes for them by hand. Each strand is connected to a relay, then driven by an Arduino. They turned out great as you can see in the clip after the break.

This is a timely hack, because it uses plain old while incandescent bulb strands which will be going on sale in the next few days. Usually you can get them on clearance for a dollar or less so plan ahead and hit the big box store early.

If you haven’t yet wrapped up your Christmas shopping, you may want to consider building [AlanFromJapan’s] implementation of the ever-classic “Clapper”. With its theme song burned into the brain of anyone old enough to remember the 80s, the clapper was a wonderful device that certainly put the “L” in laziness.

Looking for an excuse to play around with an opamp and microphone [Alan] decided to build his own version of the Clapper based off this similar circuit, which he calls the ClapClap. He built the device using an electret mic that feeds a signal through a small amplifier on the way to the ADC of an ATmega328 microcontroller. The mcu constantly polls the ADC looking for the sound of clapping hands, a solution that works, but isn’t as clean as [Alan] wanted.

He went back to the drawing board, this time building a circuit around an ATtiny2313 microcontroller. Most of the other components remained the same, though the new, smaller design sports some nice PCBs he had made at Seeedstudio. Rather than constantly polling the ADC, this version of the ClapClap looks for peaks in the signal coming from the mic to identify the clapping of hands.

He says that the newer version works great, though he still has a software bug or two that need fixing before he parks himself on the couch for all eternity.

14 year-old [Connor Smith] has been busy this holiday season, thinking up ways to improve the lighting situation at home.

A few weeks ago he put together this 3-channel light controller to toggle his parents’ external lights, incorporating an Arduino for control. The Arduino was used to switch the channels on and off at specified intervals in order to create a simple light show on the house’s exterior. Not satisfied with just a few strings of blinky lights, he took his controller back inside for some additional modifications.

He had grown tired of crawling behind the Christmas tree to plug and unplug it every day, and decided to make things easier on himself. He stripped the IR receiver out of an old VCR and interfaced it with the Arduino in his light controller using the IRremote library. After taking a bit of time to decode the values for two infrequently used buttons on his TV remote, he had himself a Christmas tree light switch that he could activate from across the room.

Check out the short video below to see his remote switch in action.

When [Todd Harrison’s] Christmas lights stayed on well past the pre-defined shut off time, he knew there was something wrong with the timer. He took the device into his workshop and spent some time diagnosing and repairing the device, a process he recorded for all to see.

After busting the screw-less timer open with a hammer, he inspected the PCB for any apparent signs of damage. After seeing what looked like a damaged transistor, he desoldered it from the board for testing. After the transistor passed his tests with flying colors, [Todd] assumed that the fault had to be in the relay which the transistor was responsible for switching.

Sure enough, the relay had shorted out, and upon cutting it open he found that the contact points were fused together. He separated and sanded the contacts down, enabling him to get the timer working – at least for the time being.

Part of [Todd’s] goal with this video was to show off different methods of desoldering, including a manual solder sucker (my favorite), desoldering braid, and a purpose built desoldering iron. If you’re in the market for some desoldering tools, but don’t know what to buy, [Todd] is more than happy to offer his advice.

Continue reading to see a video of [Todd's] troubleshooting process.

[Eric Ayars] has a nice cast iron Christmas tree stand at home, but the only drawback is that the stand makes it hard to see just how much water is available to the tree. Last year we covered a small gadget he created to help keep tabs on the water level, but as several of you predicted, the system eventually failed.

His previous solution used copper plated proto board to sense how much water was in the stand, but the leads corroded in about a week’s time. With Christmas just around the corner, he decided to give things another try.

His revamped water level sensor relies on measuring capacitance changes in a copper strip board when under water rather than detecting a complete circuit like the previous model. To protect his sensor this time around he coated the board with polyurethane, which should provide a decent corrosion barrier.

Using the Arduino CapSense library, the sensor can detect the presence of water, signaling an alarm if the base needs refilling. One of our readers suggested that he use the tree itself as a low water indicator, which is just what [Eric] did this year. If the water is somewhat low, the Arduino-controlled relay powering the tree is switched off and then on again, every 5 seconds. If the base is nearly dry, the tree asks for water by blinking the word “Water” repeatedly in Morse code.

We think that this year’s solution is pretty clever, and we’re glad to see that [Eric] didn’t give up after last year’s setback!

[Peter] was tired of crawling behind his desktop computer to switch between headphones and speakers. We feel his pain, as the headphone port on our computer speakers has its own demonic hum rendering the jack useless to us. His solution was to build this output selector board, then control it via the network.

A relay is responsible for routing the single input to one of two outputs. One output is wired to the normally closed pin on the relay, the other to the normally open pin. The important thing here is to make sure you have a separate audio ground so as not to pick up noise from the rest of the hardware.

What you see above is only the switching circuitry. This is where [Peter] went a little overboard, using an Arduino along with an Ethernet shield to drive the relay via a transistor. For this particular application there must be an easier way. But if you’re working on home automation from your smart phone, this might be just the thing to make your audio setup browser-controlled.

[via Build Lounge]

It turns out that as the days get shorter, chickens lay fewer eggs. But you can trick them into keep up production using artificial light. [Jpitz31] decided to build his own timed coop light to bridge the gap until the days of plentiful sunlight return.

He already had an LED camping light to use, but needed to find a way to power it and to switch it on and off on a schedule. He chose an ATmega328 for the latter, as he had a bunch of extras sitting around. As for power, there isn’t AC available where the coop is, so he opted for a 12V lead-acid battery with hopes of adding solar charging features in the future.

Switching is handled by a relay, with accurate time kept by a DS1307 real-time clock (it’s the red PCB seen above). Everything fits nicely on the board, and we have a couple of feature suggestions for future improvements. The linear regulators will eat up some extra power so moving to a switching regulator will help save juice. Also, it would be very easy to add a light sensor so that the light will only be on when the ambient light drops to a preset level. This way he won’t need to mess with the schedule as the length of the days change.

[Bart] built a couple dozen Pololu compatible relay drivers.

If you have a Reprap, you’re probably familiar with the Pololu stepper motor driver. These tiny pieces of kit provide stepper motor control for Gen 6, RAMPS, or Sanguinololu Reprap electronics. There’s a small problem with all these boards, though; there’s no way to control any high-power devices from these boards except for stepper motors. Controlling a spindle for a home-built CNC router would be great, but apart from attaching a Dremel to your x-axis, you’re just about out of luck.

[Bart]‘s relay driver takes the step and direction inputs from the stock Pololu stepper driver and connects each of those to a MOSFET. From there, a relay can be hooked up to the driver to control the spindle for a router, or a whole bunch of fans for a homebrew laser cutter.

The schematic and Gerber files are up on [Bart]‘s webzone. The part count is very low, and the entire board could easily be built on a piece of perfboard. Check out the demo on the other side of the jump.

[Kyle] was looking for a way to spice up his boring brick-wall dorm room. The Christmasqualizer he came up with brightens up his room and would make an awesome place for a rave.

The strings of lights in [Kyle]‘s Christmasqualizer are off-the-shelf Christmas lights. A simple circuit for the 7-band equalizer was built following this article. The build uses an MSGEQ7 equalizer chip takes audio from any source. The volume level of the seven EQ bands are output to an Arduino over a serial connection.

After the EQ chip was connected to the Arduino, [Kyle] needed a way to switch the strings of Christmas lights on and off. A few solid state relays later, and he was in business.

All the code for the Christmasqualizer is up on github. The sketch is pretty simple – connect the EQ chip as per the article, then connect the relays to the output pins on the Arduino. It’s a fun and easy project that really livens up a dorm room.

Finally, the USB port on the back of your television can be tapped for something useful. [Don] is using this add-on device to automatically cut the power to his Ambilight clone. Initially, he got tired of unplugging the power adapter each time he shut off the television, so he added a switch. But laziness overcame him and he decided he needed an automatic method. After probing around on the connections available, he established that the serial interface (normally used for servicing the device) was not of any use, but the USB port is. He measured the voltage of the power bus to be 5V when the TV is on, and 0.15V when it is off. He whipped up the circuit you see above which uses the USB connection to trigger a relay, connecting power to his Ambilight clone when the television comes on, and disconnecting it when the set is switched off.

Our dream has always been an XBMC capable device that can Velcro to the back of a TV, and be powered from that USB port. Unfortunately the Beagle Board hasn’t yet made it to a stable level when running XBMC. Our next hope is the AppleTV 2, which can run XBMC but would require some hacking to get it working off of the USB port, raising concerns about how much current it would draw at 5V.

[Pete Mills] was browsing around online when he came across an arcade button light switch and immediately wanted one. He didn’t however want to pay the $35 asking price for the switch, so he decided to build it himself.

He says that his solitary arcade machine doesn’t warrant its own room, so he figured he would wire the switch up to an extension cord in his workshop instead. The switch was made with parts he had on hand, so seeing as he didn’t have any triacs, he opted to use a relay in its place. He thought about how he would construct a simple flip flop circuit for the switch, and settled on using a simple 555-based circuit instead of a pair of transistors.

The end result looks every bit as nice as the version available for sale online, and it works great as you can see in the video below. [Pete] has circuit schematics available on his site should you want to build your own, so if you do, let us know in the comments – we’d love to see different variations on the circuit design.

After seeing many projects that use microcontrollers to switch mains voltages [Rob Miles] decided to share his preferred method. The shots you see above are an enclosed relay, part number RIBTU1C manufactured by Functional Devices Inc.

This in itself is not the full control scheme that he uses, but it takes care of the bulk of the hardware. He uses a triggering circuit based on a 555 timer (PDF). [Rob] mentioned that if you shop around, you can get the relay, 555 timer, and other components for under $15. This is a great solution for the money when you consider that you get an enclosure meant for handling high voltage and a nice terminal block to which you can connect the mains wiring. The relay itself can be triggered by a 9V battery via the transistor in the control circuit.

Notice the protoboard in the image above. There’s plenty of room for your driver circuit to rest inside the box, protected by that barrier from the HV circuitry. Check out the rest of the images he sent us after the break.

There’s a soft spot in our hearts for pointless projects, as long as they’re well executed. [Bertho] really hit the mark with his take on the most useless machine. We’ve seen several renditions of this concept, most of them hinging on a box that will turn a mechanical switch off whenever you turn it on. But this take uses a push button to activate a switch flipping mechanism on another part of the machine.

You can see the drive gears in the image above. The final gear has a small bar which flips a switch to one side or the other. The circuit does this without the need of a microcontroller. A 7400 series NAND gate chip, some passive components, and two mechanical relays are all it takes. At each push of the button, the logic chip trips one of the relays to trigger the appropriate motor direction based on the current state of that switch. You can press the button during movement, but all that will do is delay the inevitable flip of the switch.