Build Your Own Metal Detector

July 25, 2013 by Mike Szczys 35 Comments

[Dzl] and his rather serious looking son are metal detector enthusiasts. But when they couldn’t find their store-bought metal detector earlier this summer they just went ahead and built their own. [Dzl] starts his write up with an explanation of how most oscillator based metal detectors work. This one differs by using an Arduino to read from the metal detecting coil.

The circuit starts with an oscillator that produces a signal of about 160 kHz which is constantly measured by the Arduino. When metal enters the coil it alters the frequency, which is immediately picked up the Arduino. Instead of that characteristic rising tone this rig uses a Piezo buzzer, issuing the type of clicks you’d normally associate with a Geiger counter.

The last part of the build was to find the best coil orientation. They settled on thirty turns around a metal bucket. An old Ikea lamp is the perfect form factor to host their hardware which seems to work like a charm.

Predator Suit For Monsterpalooza Includes Over-engineered Shoulder Cannon

July 24, 2013 by Mike Szczys 11 Comments

off-the-hook-predator-suit

This Predator suit was premiered at this year’s Monsterpalooza conference. It’s nothing short of incredible. But the shoulder cannon is really what caught our attention. The thing is fully motorized and includes sound and light firing effects.

We saw a glimpse of what [Jerome Kelty] is capable of about two years ago. He was showing off an Arduino-based animatronics platform he put together for a Predator shoulder cannon that tracked based on where the predator’s helmet was pointing. But other than a video demonstration there wasn’t much info on the that actual build. This post makes up for that and then some.

A replica of this quality is rarely the work of just one person. A team of fans joined in to make it happen. After getting the molded parts for the backpack and canon from another team member [Jerome] set out to fit the support structure, motors, and control electronics into the space available. That meant a ton of milling, cutting, and shaping parts like the support arm seen above which integrates a servo motor into its rectangular outline. All of the controls fit in the backpack, with cables running to the helmet, as well as the cannon.

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Easy LCD Control For Arduino Mega

July 24, 2013 by Mike Szczys 10 Comments

arduino-mega-easy-lcd-adapter

[Andy Brown] wrote in to show off the TFT LCD adapter he’s been working on for connecting inexpensive displays to an Arduino Mega.

These TFT LCD screens can be picked up on eBay for a few dollars. But they’re more suited for 16-bit microcontrollers which operate at 3.3V levels. His adapter board, which plugs directly into the Mega’s dual-row pin header, makes it easier to control these with an 8-bit chip that is running at 5V.

There’s a couple of things that make this happen. First off, he’s included level converter chips to managed the 3.3V/5V issues. Second, he uses latch chips to translate eight pins on the Arduino Mega to sixteen pins on the display. Those chips have a latch pin which holds the output values in memory while the input pins are changed. He manages to drive the latch on just one of the chips using the chip select (CS) line called for by the LCD protocol. This means you don’t lose any extra pins.

Another way to uses the displays with Arduino is to use a smart controller for TFT screens.

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Arduino Cellphone

July 20, 2013 by Mike Szczys 27 Comments

OLYMPUS DIGITAL CAMERA

The fact that you can build a cellphone around an Arduino is pretty neat. But we’re drawn to this project more as a testament to the advancement of hobby electronics. An [Average Joe] can build this thing with a minimum or background knowledge and without breaking the bank. Wow.

Of course this isn’t the first DIY cellphone we’ve come across. One of our favorites is this one which resides on a home etched PCB. There was even another Arduino offering with similar components back in September. But the one seen above really pulls it all together into a package that is usable for everyday life. The components include and Arduino Uno, GPRS shield from Seeed Studios, a TFT touch screen, Lithium battery and charging circuit, and a few other bobbles. All of it is mounted inside of a 3D printed case.

A simple phone calls for a simple UI and that’s included as well. The main menu has two buttons, one for placing a call, the other for sending a text. From there you get the virtual keypad seen above for typing out the phone number or composing a message.

[Thanks Victorzie]

Hacking Quiz Game Buttons To Add A Central Controller

July 18, 2013 by Mike Szczys 5 Comments

hacking-quiz-game-hardware

The four colored buttons seen above are a product made by Learning Resources. They flash and make noise when pressed and are meant for quiz-show style games in the classroom. The problem is that they don’t use a central controller, so it’s up to the person running the game to judge who rang in first. [Kenny] fixed that issue by building his own controller which is housed in that black project box.

He went with an Arduino Uno board. It fits in the project box and has no problem monitoring all of the buttons and triggering their sound and lights when necessary. There are two telephone jacks (RJ11 connectors) on either side of the controller. He also cracked open each button, cutting some traces on the PCB in order to patch the signals into connectors he added to the housing.

The video after the break shows the system in action, In addition to illuminating the first button to ring in there are LEDs on the box that indicate who was 2nd, 3rd, and 4th in line.

If you don’t want to purchase buttons try making your own with some cheap plastic bowls.

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Robot Theater Isn’t So Much For The Actors As The Stagehands

July 17, 2013 by Mike Szczys 24 Comments

robot-theater

[Chris Rybitski] developed this low-profile robot to help move scenery on stage. The test footage shows it to be spry and able to move hundreds of pounds of cargo. The demo shows the addition of a wooden platform about twice the length of the metal chassis with casters at each end to support the extra weight. It seems to have no problem moving around with the weight of a couple of human passengers on board.

Crafty systems for changing huge sets has long made the theater a natural breeding ground for hacks. Balanced turn tables, rails systems, and the like are common place. But we think this has a ton of potential. Right now the electronics seem convoluted, as there is an Arduino running the motors which connects to the LAN using an Ethernet shield and that Linksys wireless router.

We think he should patch directly into the serial port of the router. If he loads DD-WRT or OpenWRT he can easily make the remote control a web interface. We also wonder about the possibility of making it a line-follower that can precisely position itself automatically using patterns on the floor.

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Filtering Out Mains Hum From ADC Samples

July 15, 2013 by Mike Szczys 19 Comments

Hum_filter

A little light reading means something different to us than it does to [Hamster]. He’s been making his way through a book called The Scientist and Engineer’s Guide to Digital Signal Processing written by [Steven W. Smith, Ph.D]. Being the hacker type, a million different uses for the newfound knowledge popped to mind. But as a sanity check he decided to focus on a useful proof of concept first. He’s come up with a way to filter out the mains hum from Analog to Digital Converter samples.

Mains hum is all around us; produced by the alternating current in the power grid that runs our modern lives. It’s a type of interference that can be quite problematic, which is on reason why we see EMF sensor projects from time to time. Now you can filter that ambient interference from your projects which take readings from an ADC. This would be quite useful for applications which measuring teeny signals, like ECG hacks.

[Hamster] did a pretty good job of presenting his demonstration for the uninitiated. He even provides examples for Arduino or FPGA projects.