relay

185 Articles

Controlling Your Christmas Lights Without Ever Getting Off The Couch

December 18, 2011 by 11 Comments

remote-xmas-tree-light-switch

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.

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Troubleshooting Household Light Timers

December 13, 2011 by 13 Comments

timer-repair

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.

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Christmas Tree Water Sensor Gets An Upgrade And A Fancy New Box

December 7, 2011 by 9 Comments

xmas-tree-water-sensor

[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!

Audio Output Selection Courtesy Of The Internet

November 15, 2011 by 37 Comments

[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]

Chicken Light Keeps Up Egg Production

November 13, 2011 by 10 Comments

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.

Pololu Compatible Relay Driver

October 28, 2011 by 3 Comments

[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.

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Christmasqualizer Is The Next Light Switch Rave

October 15, 2011 by 25 Comments

[youtube=http://www.youtube.com/watch?v=la1OuczS_wM&w=470]

[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.