A Motion Activated AC Switching Circuit using Mostly Discrete Components

AC motion switch

If you’ve ever dealt with a brightly lit Christmas tree, you might understand the frustration of having to crawl underneath the tree to turn the lights on and off. [brmarcum] feel’s your pain. He’s developed his own motion activated AC switching circuit to turn the lights on and off automatically. A motion sensor ensures that the lights are only on when there are people around to actually see the lights. The circuit also has an adjustable timer so [brmarcum] can change the length of time that the lights stay on.

The project is split into several different pieces. This makes the building and debugging of the circuit easier. The mains power is first run through a transformer to lower the voltage by a factor of 10. What remains is then filtered and regulated to 9VDC. [brmarcum] is using a Parallax PIR sensor which requires 4.5V. Therefore, the 9V signal is then lowered once more using a voltage divider circuit.

When the PIR sensor is triggered, it activates the timer circuit. The timer circuit is driven by a 555 timer. The circuit itself was originally borrowed from a classic Forrest Mims book, though it was slightly modified to accommodate the PIR sensor. The original push-button trigger was removed and replaced with the signal from the PIR sensor. The only problem is that the circuit was expecting a low signal as the trigger and the PIR sensor outputs a high signal. [brmarcum] resolved this problem with an NPN BJT to invert the signal. Once the timer is triggered, it flips on a relay that allows the mains electricity to flow through to the lights.

[brmarcum] soldered the entire circuit onto a piece of protoboard. The final product was then mounted securely inside of an insulated plastic case. This allows him to mount the circuit safely underneath the Christmas tree skirt. The PIR sensor is kept external to the enclosure and wired up into the tree itself. This allows the sensor to still detect motion in the room while the rest of the circuit is hidden away.

[via Reddit]

3D printed Christmas cookies

3d-printing-christmas-cookies

Here is yet another way to get into the holiday spirit at your local Hackerspace (or at home if you’re happen to have your own 3D printer). [Ralph Holleis] wrote in to show off his 3D printed Christmas cookies. The majority of the info on this project comes from the video embedded after the break. The extruder head he’s using includes a syringe which is filled with what we assume is Spritz Cookie dough. It is squeezed out in a pattern before heading to the oven for baking.

[Ralph] mentioned that he’s using UNFOLD Pastruder as the print head. We looked and couldn’t find that exact design, but it seems like it might be related to this Claystruder head designed by a user named [Unfold]. If you have the exact link to the extruder design seen above please let us know in the comments section.

If you don’t already have this type of head it’s just a matter of printing the mounting brackets and buying a syringe to match. But you’ll also need compressed air and a valve to regulate the flow of dough. It might be easier just to print your own cookie cutters. This is a great project for people who don’t have access to a laser cutter for gingerbread house work.

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Deck the cubes

deck-the-cubes

[MrBuildIt] has lived up to his name when it comes to this year’s Christmas decorations. He built a rig that spreads Christmas cheer from one end of the cubicles to the other.

In the demo video after the break you’ll see that the system is controlled by a nicely polished Android app. It lets you choose from three different Christmas songs (or no music at all) as Santa Claus makes his rounds. The app includes buttons for switching all of the lights on or off but we think it’s more corny fun to see then turn on as Santa flies overhead.

The sleigh and three tiny reindeer are suspended from a pulley system. When they make it to one end of the office a hall effect sensor serves as a limiting switch. From the look of it you’d think Santa will be flying backwards on the return trip but there is a servo that flips the thing around so that he’s going the right way.

This is quite a gaunlet to have thrown down when it comes to office decor. We’d like to see what geeky thing’s you’ve been doing with your own decorations. Get some details up on the web and send a link our way!

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Christmas light controller is its own percussion section

clicking-christmas-tree-controller

[Jason] and his father took advantage of a week off of work over Thanksgiving to design and build a Christmas light decoration that can flash fancy patterns. He calls it the Uno Christmas Tree. It’s sixteen strands of lights draped between a pole and the ground to form the shape of a tree. The main controller is an Arduino UNO, but what really makes this work is a mechanical relay board with sixteen channels.

Using trigonometry they figured out that the decoration would be fifteen feet tall and have a five-foot radius at the base. A pipe was installed to act as the trunk, with an old toilet flange at the top and stakes at the bottom to anchor the lights. They all make their connections at the controller box using extension cords that were labelled with channel numbers. You can see the final product in the video after the break. But you’ll also want to watch the clip on [Jason's] blog which shares the sonic symphony created when the mechanical relays really start working.

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Electronic ornament will definitely put [Dave] on Santa’s “naughty” list

mischievous-xmas-ornament

[Dave Vandenbout] says that his sister has gotten big on Christmas traditions, and decided that the whole family should start making ornaments for the tree each year. Not one to let a chance to tinker with electronics pass him by, [Dave] started brainstorming the perfect electronic ornament for their tree.

He settled on the Christmas tree design you see above, which will eventually hold 15 RGB LEDs. On the back of the board, he is planning on mounting a PIC 18F27J53 microcontroller, which will take care of the LED display along with his other more mischievous components.

You see, undeterred by his sister’s holiday spirit, [Dave] wants to arm the ornament with a foul mouth, and have it attempt to shake other ornaments off the tree. To do this, he’s installing a vibrating motor on the back of the PCB, along with a speaker and MicroSD card to provide the ornament’s sound bites.

To be honest, we think his idea is pretty entertaining, we can only imagine the look grandma will give when the cute, light up Christmas tree ornament blurts out, “Eat me Santa!”

We just hope he sends some video our way once he wraps up the project.

GE Color Effects hacking for the nautically inclined

ge-color-effects-controller

[Jim] wrote in to share some work he did with GE Color Effects LED lights in an effort to create a light display for his boat. He saw our coverage of the Color Effects G-35 hacking efforts by DeepDarc last year, and knew that they would be prefect for the boat. He did some careful scouring of eBay to score 8 strings of lights at bargain basement pricing, then he got down to the business of hacking them.

He originally built a control circuit using a single PIC18F, but just before he started to put everything together, he realized that wiring everything up would be a huge undertaking. Going back to the drawing board, he decided it would be best to replace the lights’ stock board with one of his own. Now, he uses a single master controller board to send messages to his slave “pods”, significantly cutting down the amount of wiring required for the project.

The display looks great as you can see in the video below, though as many do, [Jim] has plenty of improvements in mind for the future.

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Looking toward Christmas decor by learning about DMX

So Halloween finally arrived, we hope you had enough time to pull off your frightening feats in the way you had originally envisioned. Now it’s time again to look to the future and start planning this year’s Christmas decorations. Lights are always a popular theme, and this year you might want to look into DMX lighting controls and decide if that’s a route you want to take. [Akiba] has your back, he just put together a set of videos explaining the DMX lighting protocol and how to use it with an Arduino.

The thought here is that the Arduino can be used as a sort of DMX hub that is connected directly to a computer running open source controller hardware. It can send commands which the Arduino decodes, deciding whether to just pass them on to DMX compatible devices, or to do what it does best and control other hardware that is not normally accessible through the lighting command protocol. To the control program your four-dollar strand of LED lights looks no different from a thousand dollar stage light, making it cheap and easy to build your own entertaining holiday show right in your front yard. See the second video in this series after the break where [Akibo] details the hardware setup for his system. The other parts are available at the link above.

Be careful, this can be a consuming endeavor. Don’t believe us? Just look around and you’ll find no shortage of large DMX builds just for Christmas lights.

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