Tag Archives: Wikipedia

This geiger counter is powered by Adafruit & Atmel

The Geiger–Müller counter, also known as a Geiger counter, is an instrument used for measuring ionizing radiation. According to Wikipedia, the device detects radiation such as alpha particles, beta particles and gamma rays using the ionization produced in a Geiger–Müller tube.

Recently, Johan of dynode.nl designed geiger counter powered by Adafruit’s Atmel-based (ATtiny85 MCU) Trinket.

“Lately I have been messing around a bit with microprocessor powered geiger counters. One smart guy came up with the idea of generating high voltage using PWM signals from the microprocessor itself,” Johan explained in a detailed blog post.

“With some additional external parts a HV supply and negative going pulse suitable for microprocessors is easy to make.”

So, how does the circuit work? Simply put, a ~1 Khz squarewave turns the MPSA44 high voltage transistor on and off – generating high voltage when the inductors current is shut off.

As Johan notes, the specific voltage is contingent upon the pulse width of the square wave which can be tweaked on a software level.

“The 1N4007 diode rectifies this voltage, and the HV cap removes most of the ripple on this voltage. The resistor limits current to the GM tube,” he continued.

 “The current pulses from the tube generate a voltage drop over the 100K resistor which turns on the BC546. When this happens, the voltage [via] the 10K resistor is pulled to ground, generating a negative going pulse each time the GM tube detects an ionizing ray or particle.”

It should also be noted that Johan’s design supports serial logging capability using a tx only software serial library tasked with outputting the measurements in CPM every 10 seconds on pin 4.

So, what’s next for the Trinket-powered geiger counter? Well, Johan says the platform still requires some tweaking, as the circuit is quite susceptible to electromagnetic interference which causes erroneous counts.

Interested in learning more? You can check out the project’s official page here.

Let’s go Charlieplexing!

Charlieplexing is a technique proposed in early 1995 by Charlie Allen at Maxim Integrated for driving a multiplexed display in which relatively few I/O pins on a microcontroller are used to control an array of LEDs.

According to Wikipedia, the method employs the tri-state logic capabilities of microcontrollers in order to gain efficiency over traditional multiplexing. Indeed, most Makers have likely encountered a project where multiple LEDs are required – with only a few wires.

As Ochâtelain notes in a recent Instructables post, Charlieplexing using an Atmel-based Arduino board may very well fit the bill.

“With only four wires you can drive 12 LEDs with only four resistors as an optional protection and without any ‘intelligent’ component like a 74595 or similar,” ochâtelain explains.

Recommended project components?

  • 4 RGB LEDs (or 12 single color LEDs)
  • Atmel-based Arduino board
  • 4 resistors
  • Breadboard
  • 4 PIN male headers

Ochâtelain kicks off the project by prepping the stripboard.

“We will add a resistor to each strip, so just leave two rows in the beginning of the strips empty – one for the headers, one for the start of the resistor, cut (= isolate) on the third row of holes, the LED will be plugged starting from the forth row,” he writes.

“To simplify the bending, we mark the stripboard distance on every pin all LEDs. This way it is very easy to bend the pin the required strip. Please be aware to keep always the same ‘orientation’ of your LEDs. In this case Pin 3 is always the anode.”

Next, Ochâtelain defines the specific bending pattern and plugs the LEDs into the stripboard.

“Now comes the easy part: Just solder all the LED-PINs, then the 4 resistors (I first used 3k3 throughholes and then 0k5 SMDs) and the 4 header pins,” he adds.

“Keep a sharp eye on any short-circuit on the front and back side of the board.”

Last, Ochâtelain tests the system with a Charlieplexing Arduino sketch. 

Interested in learning more about Charlieplexing with an Arduino? You can check out Ochâtelain’s Instructable page here.

Long-range RC controllers for UAVs

Mike and his team recently decided to extend the range of a basic remote control setup for a UAV project.

Ultimately, Mike’s crew decided on a pair of Atmel-powered Arduino Mini boards and Digi Xtend 900Mhz modems to get the job done.

As HackADay’s Will Sweatman notes, the 1 watt transceivers provide a fantastic range of approximately 40 miles.

So, how did Mike do it?

“He set the transmitter up so it can plug directly into any RC controller training port, decoding the incoming signal and converting it into a serial data package for transmitting,” Sweatman explained.

“While they don’t provide the range of other RF transmitters we’ve seen, the 40 mile range of the modem’s are more than enough for most projects, including High Altitude Balloon missions.”

Interested in learning more? The code for the Arduino transmitter system is available on GitHub here, while a Wikipedia page about the project can be accessed here.

Atmel-based BASIC computer

 makes us nostalgic

BASIC, or Beginner’s All-purpose Symbolic Instruction Code, is a series of general-purpose, high-level programming languages that emphasizes ease of use. According to Wikipedia, John G. Kemeny and Thomas E. Kurtz designed the original BASIC language at Dartmouth College in New Hampshire way back in 1964.

Multiple dialects of BASIC were written over the years, with the TinyBASIC variant capable of fitting into as little as 2 or 3 KB of memory. This small size made it quite useful in the early days of microcomputers (the mid-1970s), when typical memory size weighed in at 4–8 KB.

Recently, a Maker named Dan decided to design a simple, tiny 8-bit computer to run the succinct TinyBASIC.

As HackADay’s Brian Benchoff reports, the computer is built around the Arduino Uno (ATmega328) and a custom-made AVR-based shield, using TinyBASIC, the TVout library and the PS/2 keyboard library.

“After piecing together a little bit of code, the Arduino IDE alerted Dan to the fact the TVout and PS/2 libraries were incompatible with each other,” Benchoff explained. 

”This inspired Dan to use the ATmega328 as a coprocessor running the TVout library, and using the capacious ATmega1284P as the home of TinyBASIC and the PS/2 library.”

Subsequently, Dan used Fritzing to design a circuit using minimal components, with a custom PCB milled out of copper board.

“After the board was tinned, [Dan] had a beautiful minimalist retro computer with nearly 14kB of RAM free and an RCA display,” added Benchoff. 

The final setup comprises the shield, an Arduino UNO, PS/2 keyboard, RCA capable display (such as an LCD TV), RCA cable and a power source (such as a wall mounted PSU).

Future iterations of the Atmel-powered TinyBASIC computer will likely be based around the stalwart Arduino Mega (ATmega1280), facilitating a TV resolution of 720×480. Additional features could include an SD card slot, LEDs, pots and perhaps even headers for I2C and SPI.

Interested in learning more?

You can check out the project’s official Instructables page here.

Teaching Earth Science with 3D printing

Ryan Cain – who teaches Earth Science to second graders – wanted to finish the most recent semester with a special, interactive project.

To help his class emphasize with hurricane victims, Cain decided to teach his students how to design their own buildings using 3D modeling software and MakerBot Replicator 2 3D printers. The structures were then placed along the banks of a simple model river consisting of a water pump and a sandbox.

“By turning up the power on the water pump, Cain unleashed a flood on his class’s model city,” MakerBot’s Ben Millstein explain in a recent blog post. “This gives students a memorable visual on the effects of soil erosion.”

Erosion is the process by which soil and rock are removed from the Earth’s surface by exogenic processes such as wind or water flow – and then transported and deposited in other locations.

According to Wikipedia, excessive erosion causes problems such as desertification, decreases in agricultural productivity due to land degradation, sedimentation of waterways and ecological collapse due to loss of the nutrient rich upper soil layers. Industrial agriculture, deforestation, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion.

Unsurprisingly, teaching second graders how to design and 3D print an entire riverbank of model buildings isn’t the only impressive thing Cain has done with his MakerBot 3D Printers, as he recently:

  • Embarked on a “30 days of creativity” project, starting with 3D printing a replacement knob on his dresser.
  • Printed new buildings for his erosion model.
  • Taught his robotics students how to design and 3D print concepts for relief delivery drones that could reach victims in the wake of natural disasters.

“Cain has been a fan of MakerBot since the Cupcake CNC,” Millstein noted.

“He was also one of the first educators to bring MakerBot 3D Printers into the classroom. We can’t wait to see what this pioneering educator will come up with next!”

As we’ve previously discussed on Bits & Pieces, the DIY Maker Movement has been using Atmel-powered 3D printers like MakerBot and RepRap for some time now. However, 3D printing has clearly entered a new and important stage in a number of spaces including the medical sphere, architectural arena and science lab.

Indeed, the meteoric rise of 3D printing has paved the way for a new generation of Internet entrepreneurs, Makers and do-it-yourself (DIY) manufacturers. So it comes as little surprise that the lucrative 3D printing industry is on track to be worth a staggering $3 billion by 2016.

EKG with an Arduino Uno (ATmega328)

Wikipedia defines electrocardiography as a transthoracic (across the thorax or chest) interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the surface of the skin and recorded by a device external to the body. The recording produced by this noninvasive procedure is termed an electrocardiogram (ECG or EKG).

Recently, a Maker by the name of birdyberth designed an Arduino-based electrocardiograph and heart rate monitor. The open source project files, along with build details, were posted to Instructables.

“[This] is intended to be a fun science project only [so] it should not serve a medical purpose. To avoid any risk of electric shock, only use battery alimentation,” he explained. “Electrodes are theoretically isolated from the circuit by the instrumentation amplifier, but [better to] play [it] safe.”

Key projects components include an Atmel-based Arduino Uno (ATmega328), instrumentation amplifier, LCD, voltage regulator, mini speaker, bright LED, diodes, 9V batteries, breadboard, jump wires, resistors, capacitors, electrodes, speaker wired, antistatic wrist strap, medical tape, aluminum paper, paper clips, shower gel (substitute for electrocardiogram gel) and an oscilloscope (optional).

As you can see in the schematic above, the two electrodes link with pin 2 and 3 of the INA128. An additional reference electrode (an antistatic wrist placed on the right leg) is plugged in ground, a configuration that allows the use of unshielded cables.

“The best signal is just after the low-pass filter (between the two 100kOmhs resistors),” said birdyberth. “I suggest you plug the oscilloscope probe at this point for demonstration, although you might want to check other points to see if everything is working properly.”

Interested in learning more? You can check out HackADay’s coverage here and the official Instructables here.

Video: Playing Tekken with a piano (and Due)

Tekken is a popular fighting game franchise created, developed and published by Namco. Beginning with the original Tekken in 1994, the series has seen several sequels, spin-off titles and even three films.

According to Wikipedia, the Tekken storyline typically documents the events of the King of Iron Fist Tournament, hosted by the Mishima Zaibatsu corporation. The prize? Control of the company, allowing the winner to host the next tournament.

Recently, a modder by the name of “MC Cool” decided to put a new spin on the classic title by using an Arduino Due (SAM3X8E ARM Cortex-M3 CPU) paired with an Xbox 360 to create the TekkenPiano.

“The piano sends a MIDI-signal, which is transferred to an Arduino,” MC Cool explained in his Vimeo description. “[Based on] the signals, the Arduino triggers transistors, which then trigger inputs on a paewang PCB (the PCB of an arcadestick). The paewang is connected to an Xbox360, [although] you can also use it on PS3.”


Simulating a minicomputer (PDP-11) on an Atmel MCU

The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from around 1970 until the 1990s.

Image credit: Wikipedia

According to Wikipedia, the PDP-11 offered a number of uniquely innovative features and was easier to program than its predecessors due to the inclusion of additional general-purpose registers. Perhaps most importantly, the very first officially named version of Unix ran on the PDP-11/20 in 1970.

Recently, an engineer named Dave Cheney kicked off a project to simulate the PDP-11 using a board powered by Atmel’s versatile ATmega2560 microcontroller (MCU) and a custom-built SPI SRAM shield. Combined, the two components form a platform aptly dubbed “AVR11.”

“Today the simulator boots V6 Unix and can execute some simple commands. [Yes], there are some remaining bugs in the mmu which cause the simulator to fail when larger programs (/usr/bin/cc and /usr/games/chess for example) are executed,” Cheney explained in a blog post describing the project.

“The hardware emulated is somewhere between a PDP11/40 and PDP11/45. The EIS option (MUL and DIV) is properly emulated, but FIS (floating point is not). Only a single RK05 drive is simulated, backed by a file on the micro SD card.”

Cheney says he ultimately plans on improving the accuracy of the simulator so it can run V7 Unix, 2.9/2.11 BSD, RSX-11M and even the original DEC diagnostics. In terms of speed, Cheney confirms the simulator is approximately 10x slower the an original 11/40.

“I was never expecting to be amazed with the speed of this simulator, especially at this early stage. However, on a performance per watt basis, I think it’s hard to beat AVR11. The PDP-11 that this simulator models is spartan, even by the standards of the early 70s, yet still consumed over 2 kilowatts of power for the CPU and memory (256kb),” he continued.

Image Credit: Wikipedia

“The 2.5 megabyte RK05 boot drive was another 600 watts. Real Unix installations would have three or more drives, so there goes another 1200-1800 watts. Compared to that, the AVR11 draws well under the 500ma limit of a USB port. Although I lack equipment to measure the current draw I estimate it to be around 100ma at 5 volts which is 0.5 watts.”

Interested in learning more about simulating a PDP-11 with an Atmel MCU? You can check out Dave Cheney’s project page here or download the relevant code from GitHub.

Astrophotography tracking

 with Atmel’s ATtiny85

Astrophotography describes the imaging of astronomical objects along with large areas of the night sky. According to Wikipedia, the first photograph of an astronomical object (the Moon) was taken in 1840, although it was not until the late 19th century that advances in technology allowed for detailed stellar photography.

Image Credit: Wikipedia

In addition to recording the details of objects such as the Moon, Sun, and planets, astrophotography is also capable of imaging objects invisible to the human eye such as dim stars, nebulae and galaxies. This accomplished by long time exposure, as both film and digital cameras can accumulate and sum light photons over extended periods of time.

As HackADay’s John Marsh notes, the basic idea is to capture images otherwise undetectable by the human eye through longer exposures.

“Unfortunately, the big ball of rock we all inhabit has a tendency to rotate, which means you need to move the camera to keep the night sky framed up,” he explains.

Unsurprisingly, the vast majority of professional astrophotography trackers require precision parts and fabrication. However, a Maker by the name of ZigZagJoe found an alternative with Chris L. Peterson’s stalwart Cloudbait Observatory model. 

Dubbed the “Barn Door Tracker,” the platform is powered by Atmel’s ATtiny85 microcontroller (MCU) and runs a pre-configured table that determines step rate against time.

Interested in learning more about ZigZagJoe’s ATtiny85-powered astrophotography tracker? You can check out the project’s official page, along with additional pictures here.

Arduino Uno powers this Game of Life clock

The Game of Life (aka Life) can best be described as a cellular automaton created by the British mathematician John Horton Conway in 1970. Essentially, it is a zero-player game, meaning that its very evolution is determined by an initial state, requiring no further input. Simply put, an individual interacts with the Game of Life by creating an initial configuration and observing how it evolves.

The game made its first public appearance in the October 1970 issue of Scientific American, having been featured in Martin Gardner’s “Mathematical Games” column. As Wikipedia notes, the game is rather interesting from a theoretical point of view, as it has the power of a universal Turing machine, namely anything that can be computed algorithmically can be computed within Conway’s Game of Life.

Recently, a Maker by the name of Matthews created a Game of Life style clock. According to HackADay’s James Hobson, Matthews was originally inspired by another Game of Life Clock featured on HackADay a few months ago, although he did implement a number of critical changes.

”First, Matthews wanted a much bigger playing field, so he found a 16×32 RGB LED matrix. Second, he wanted the time to always be visible so it actually works as a functional clock,” Hobson explained.

“At the beginning of every minute starts a new Game of Life which plays over top of the time displayed. Three buttons on the top allow for many adjustments including brightness, timezone, speed, colors and even edge behavior.


The Game of Life clock is powered by an Atmel-based Arduino Uno (ATmega328) paired with a Chronodot RTC module to assist with accurate time keeping.

Interested in learning more about the Game of Life clock? You can check out the project’s official page here.