Hackaday reader [Kieran] volunteers at an outdoor haunted house attraction called the “Disenchanted Forest”. Attendees are lead through the haunted forest by a volunteer, who helps keep everyone on the predetermined trail. The trail is usually lit by small LED fixtures that the group constructed, but the organizers wanted to make the lights more interactive this time around.

A fellow organizer gave [Kieran] a [Harry Potter] Magic Candle, which allows him to light the toy with the wave of his IR-enabled wand. He was told to “make it do something cool”, so he took a closer look at it to determine how everything worked.

Using an Arduino clone and some borrowed IR code he was able to get the wand to work with the forest’s trail lighting, but there was a lot of lag between waving the wand and triggering the light. Taking a second stab at it, [Kieran] was able to replicate the IR protocol used by the toy, speeding things up and increasing the wand’s range considerably. Now, the tour guides can light and extinguish the trail lighting with a simple flick of the wrist.

Take a look at the video below to see how things worked out for [Kieran], and be sure to swing by his site for more details if you have the urge to modify your Magic Candle.

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Here are the guts of [Lukasz's] infrared camera remote control. He based it off of an existing design, but looked for places where improvements could be made. He felt the ATtiny2313 was a bit wasteful in this case. But further investigation led him to see why it was chosen. If you were to drop down to an ATtiny13 the ability to connect a crystal oscillator is lost (that chip only offers a 1-pin clock signal input) and the internal RC oscillator isn’t quite up to his standards for reliable IR communications.

Instead of driving the IR LED directly from an AVR pin he used a transistor in hopes that it will allow the maximum current to flow through the diode when in use. We’re not sure if it’s necessary, but we can see how it makes sense. Power is received from an unregulated 3 volt coin cell, so maybe as that voltage drops over time this will come into play.

Speaking of that coin cell, battery life is a concern here. [Lukasz] is using the sleep functions of the AVR after three seconds of use. This should keep the cell alive for quite a long time. But his 0 volt measurement is an anomaly with the multimeter he’s using. To get a precise measurement for tiny current flow you need extra equipment, like [Dave Jones'] uCurrent adapter.

The schematic for this Canon camera compatible project is only provided in Eagle format so we’ve embedded an image of it after the break for your convenience. You should have no problem making this work with a Nikon if you swap out some of the code from the TV-B-Gone shutter release we saw on Thursday.

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After seeing a writeup online that demonstrated how to build an “Emergency Party Button”, [spikec] knew that he had to have one of his own. He happened to have a USAF B-8 stick grip from an A-10A aircraft laying around, and figured it would be perfect for controlling the A/V system in his basement.

The control stick was mounted to the top of a cheap cigar humidor, and crammed full of any electronic component he could get his hands on. It contains not one, but two Arduinos. The first is tasked with reading the flight stick’s inputs and the IR control of his various appliances, while another triggers the overhead lighting in his bar along with the X10 controlled Emergency Party System. He contemplated combining all of the functionality into one device, but splitting the tasks in two was easier for this self-declared electronics novice.

The various buttons on the control stick can be used to power all of his A/V appliances on and off, control volume levels, and select which songs stream from his digital jukebox. If the action ever starts to wind down, a quick turn of his “arming” key and the flick of a switch sends his basement into full-on party mode, which includes more lighting and lasers than any one person should be allowed to own.

[spikec] says that his wife’s eyes were rolling like “uncaged gyros” when he unveiled his controller for the first time – a sign of a job well done. Don’t take our word for it though, check out a video of his control stick and Emergency Party System in action after the jump.

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[Ron] was looking for a way to play his MP3s around the house without having to use his computer. He also wanted the ability to remotely control his tunes with an old camcorder remote he had sitting around – not exactly a feature you would find in an off the shelf personal audio player.

Ultimately, he decided to construct his own remote-controlled audio player using a VMUSIC2 audio module, which can decode MP3s from any standard USB drive. The VMUSIC2 is controlled by a Propeller demo board, which also handles receiving and decoding IR signals from his camcorder remote. While he was originally dumping ID3 tag data to his computer for debugging purposes, he recently added an LCD screen for displaying song information in a more useful manner.

The MP3 player seems to work pretty well if the video below is any indication, though it’s begging for a nice enclosure to tie things together. We like the project so far, so we’re sure [Ron] won’t fail to impress when it’s completely finished.

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[zmashiah] has a nice Nova tube amplifier in his living room, and he often forgets to turn it off once he’s done listening to music. He feels guilty when this happens, as it not only shortens the lifespan of his stereo, but it’s not exactly the greenest behavior either. Rather than let his receiver idle any longer, he built a simple device that automatically turns it off when he forgets.

He wired an Arduino to the line level output of the receiver, sampling the audio every two seconds. When five minutes pass without an audio signal, the Arduino sends an IR command to the receiver, turning it off.

He says he’s aware that it might be overkill to use an Arduino for this application, but that he would rather fork out an extra dollar or two instead of spending hours poring over AVR assembly code. While we’re all for efficiency, we can’t exactly argue with that logic – time is money!

[zmashiah] is kind enough to include his schematics as well as the code for his project, so be sure to check it out if you occasionally forget to turn off your IR-enabled appliances.

[James] is one of those guys on a quest to control everything with one device. His tool of choice is an Android phone, which can do quite a lot right out of the box. But he was never satisfied with its lack of IR remote control abilities. He fixed that feature-gap by building a Bluetooth to Infrared translator.

The hardware he used for the prototype is quite simple. A cheap serial Bluetooth modem from eBay lets him connect to his phone. An Arduino board listens for data from the modem and converts incoming commands to flashes on an IR LED. Voila, he can control the tube with his phone.

We love the potential of this hack. The Bluetooth module runs from 3.3V, and reading serial data and flashing an LED is extremely simple. You should be able to use a small uC, say an ATtiny13, and a 3.3V regulator to miniaturize the module. We could see this plugging into the USB port on the back of a TV for power, with a wire extension to put the LED into position. The only shortfall is the inability to turn the TV on remotely when drawing power this way.

Remote codes aren’t particularly large to store either. So this would be pretty easy to extend to full control of all IR-compatible home entertainment devices. You just need a tool to discover the remote control codes.

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[SpiralBrain] needed to figure out the coding scheme used by an IR remote control so that he could use it with his own project. He built an IR receiver board for the PICkit 2 and figured out how to use some of the Microchip software to measure the timing of the incoming signal.

The hardware’s dead simple; a 38 kHz IR receiver does the heavy lifting by filtering out errant infrared light. When it does detect a signal with the correct frequency the output pin drives the base of a transistor to toggle the input pin on the PICkit 2. The breakout board has a pin header which makes it a snap to detach and store for later use. The PICkit 2 Logic Tool software captures this input, by setting the correct pin as a trigger and choosing a 10 kHz sample rate.

As we discussed in our PIC programming with Linux tutorial, the PICkit 2 really is far superior to its replacement, the PICkit 3. [SpiralBrain] mentions that it is more versatile than the newer version but doesn’t go so far as to tell us whether you can use this hardware with the PICkit 3 or not.

While they are not nearly as complex as their self-navigating brethren, building line following robots is no simple task, especially when they are this small. The creation of [Ondřej Staněk], this matchbox-sized line following robot is quite impressive.

PocketBot’s 48mm x 32mm circuit board also acts as its frame, supporting the wheels, motors, microcontroller and more. The brains of the operation is an ATmega8 microcontroller mounted on the bottom of the bot. A pair of wheels are driven independently using a set of mobile phone vibration motors that power the bot at speeds of up to 0.35 meters per second. Line detection is achieved by using three different IR sensors paired with four IR emitters located at the front end of the bot.

PocketBot also has an IR receiver on its top side, which allows [Ondřej] to control the robot, tweak its parameters, or calibrate its sensors on the fly using an IR remote or his computer.

The PocketBot might not be the absolute smallest line following bot we’ve seen, but it’s pretty darn close!

Continue reading to see PocketBot in action.

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