Charging Timer For R/C Batteries

February 4, 2011 by Mike Nathan 27 Comments

arduino_controlled_socket

Santa brought [Quinten’s] son a shiny R/C truck for Christmas, but this new toy had one drawback – its batteries could only be connected to the charger for a maximum of 6 hours, lest he turn his house into a pile of smoldering ash. With grave warnings from the manufacturer dancing in his head, he searched around for a timer that would allow him to cut power to the battery after charging for its allotted time. Coming up empty, he decided to create his own timed electric socket regulated by an Arduino he had sitting around. He grabbed a project box and wired up a nice looking socket timer, complete with an LCD status display. To make things easy for his son, he added two buttons to the front of the controller – one for selecting the amount of charging time, and one to set the timer in motion. As with his previous hacks, [Quinten] has provided plenty of documentation in the form of pictures, code, and even a video of the timer in action.

Inaccurate Breathalyzer Is Still Quite Nice

January 25, 2011 by Mike Szczys 14 Comments

Sure, [Hunter Scott’s] Breathalyzer can only differentiate between hammer and sober, but look how nice it came out. He’s using an MQ-3 alcohol sensor which, from previous projects, we know is very difficult to accurately calibrate. But if you want to monkey around with embedded systems you’ve got to have a goal. [Hunter] chose a gorgeous aluminum project enclosure, adding a big LCD display to the to the lit. The switch on the bottom selects between on, off, and charging modes. He’s using a USB charger from Adafruit to top off the lithium battery inside. Everything runs on 3.3V with the exception of the sensor which gets its 5V supply from a boost converter. An Arduino is the brains that pulls everything together.

See [Hunter’s] video description of the project embedded after the break.

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Yet Another Cat Door

January 24, 2011 by James Munns 11 Comments

Cat Flap Fever

RFID cat flaps are one of those projects we see all of the time. They are generally pretty simple to rig up, not too expensive, and have a good “wow” factor for any non-technical friends or family, not to mention tremendously useful. Why did we decide to share this one? Well, for one, it is simple. It doesn’t tweet, email, or text message, it just gets the job done. Two, it is excellently documented, including a detailed parts list and a step by step schematic just about anyone could use to build their own. [landmanr] does mention that he recommends some sort of project enclosure to protect the electronics from damage, which would be bad for the poor cat stuck outside.

DIY Ultrasonic Range Finder For $5

January 24, 2011 by Chris Nelson 25 Comments

After finding some ultrasonic transducers online for a dollar each [Kerry Wong] decided to create an ultrasonic range finder. The result is much like parallax’s PING))) sensor but much cheaper. His post is not only a good way to save some money, but also does a good job of explaining how ultrasonic sensors work. The transmit circuit is essentially an H-bridge, much like what you would use to control a motor. To listen to the returning echo he uses a pair of high gain/low noise op-amps to filter and amplify the signal. The board he uses to test the range finder (not included in the cost) is an ATMega328 running the Arduino boot loader. He also provides lots of example code to boot.

Turning Music Into A Light Show

January 22, 2011 by Chris Nelson 24 Comments

[nickinoki] Made a light show using some amplifiers and an arduino. First he created a microphone circuit based around a LM386 Audio Amplifier. After amplifying the output of the microphone a second time, he uses three bandpass filters to block all but a few desired frequencies from reaching the arduino. By only letting a few frequencies through the arduino is able to determine if the song is louder at higher or lower frequencies. Then using the three analogue inputs he created a scheme for generating the light show on an arduino. While he was unable to achieve the exact target frequencies with his bandpass filters they worked well enough to allow him to successfully generate the light show.

Electronic Dice Has Option For 20 Or 100 Sides

January 17, 2011 by Mike Szczys 17 Comments

[Bluewraith] built himself an electronic dice using a 555 timer and 4017 counter. This is a classic project and he enjoyed doing it but wondered about making a 20-sided dice. So he grabbed his Arduino and got to work. A switch on the final project selects between 20 or 100 sides. He used a MAX7219 to control the 7-segment displays, and a standalone AVR chip for the rest of it.

If you missed it back in October you should also look in on this 6-sided dice. It also uses an AVR running the Arduino bootloader but a mercury switch allows the player to shake the box in order to start a roll.

One last note, we made a conscious decision to use the word ‘Dice’ instead of the grammatically correct ‘Die’ which is its singular version. We think ‘Die’ can be a bit too confusing and we’re not the only ones.

Quiz-o-Tron 3000

January 16, 2011 by Caleb Kraft 19 Comments

Who would have known that being given the task of planning a holiday party at a wine bar would turn into a hacking project? Well, here’s how that happened. A committee was in charge of the festivities and had decided on doing a mock game show. It wouldn’t really feel like a game show unless you had a contestant lockout system where the first one to hit the button gets a light and a sound while the runners-up get nothing. This is where [RoysterBot] comes in. He built the Quiz-o-Tron from 4 “easy buttons” from staples and an Arduino. After having finished it, he found the system to be somewhat lacking in the excitement area. When a button was pressed it only lit an indicator on the main Quiz-o-Tron box. He decided to add a small circuit inside each of the Easy Buttons using a 555 timer and some LEDs to give them some better feedback. Apparently he was going to patch into the speaker as well, but didn’t have time to get that added.

[via Adafruit]