Tag Archives: James Hobson

Catching drops of water with an ATmega48P

Drops of water are often captured in perfectly timed photographs with the help of an optointerrupter, light source and air gap flash.

As HackADay’s James Hobson notes, this configuration is typically expensive or difficult to put together.

Fortunately, a Maker by the name of Michal has come up with a viable alternative using an array of LEDs to illuminate the drops.

“He [uses] a IR diode, a photo-resistor, a few spacers, some plastic and a bunch of hot glue to make up his optointerrupter. When the droplet passes through the IR beam it breaks the signal from the photo-resistor which then triggers his Atmel ATmega48P [MCU],” says Hobson.

“It waits 80 milliseconds and then turns on the LEDs for approximately 50 microseconds. Meanwhile, [the Canon] camera is watching the whole event with a shutter-speed of a few seconds.”

As Michal explains in a detailed blog post, one of the nice things about using an LED configuration is that it boasts rise and fall times considerably shorter than traditional camera flash, which lights up for approximately 1-2 milliseconds, rather than 50 microseconds.

“That’s why most of the motion-stopping photography relies on more exotic air-gap flash units,” Michal concludes.

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

Reading paper ticker tapes with an Arduino



Ticker tape – in use from 1870-1970 – was the earliest digital electronic communications medium, transmitting stock price information over telegraph lines.

According to Wikipedia, it consisted of a paper strip that ran through a machine called a stock ticker, which printed abbreviated company names as alphabetic symbols followed by numeric stock transaction price and volume information.

Recently, a Maker named NeXT decided to design a custom PCB from scratch to facilitate the easy reading of paper ticker tape. As HackADay’s James Hobson notes, it is somewhat difficult to buy a working paper tape reader at a reasonable price.

“What we love about this hack is its clever reuse of perfboard — it just so happens that the spacing of his paper tape holes line up perfectly with the holes in the perfboard. Don’t you love it when engineers work together with nice, even, standard units?” Hobson writes.

“After discovering this it was just a matter of adding some photo-transistors on one side of the perfboard sandwich and LEDs on the other side. A bit of soldering, some Schmitt triggers, and an Arduino Pro Mini [Atmel ATmega168 MCU] later… and bam you have a serial output of data.”

According to NeXT, the the output can be fixed to any specific baud rate, although it is currently set at a cool 9600.

“That’s enough that I won’t overflow the serial channel, nor will it be painfully slow. It’s possible that I can change the baud rate with a jumper but I’ve yet to learn how exactly that would be programmed so we’ll leave that for another day. When I want to reprogram it the same four pin header that powers it and connects it to the host also holds an Rx pin so I can talk to it,” he says.

“In the end I decided while this makes a very nice and portable reader I decided the best home would be in my DEC LA-120 hard copy terminal. It has an option knockout on one side and you could easily build it into the overall terminal by taking the Tx line from the reader and tapping into the TxD line on the terminal’s serial port. That way so long as you were in 9600 baud mode if you wanted to read in a paper tape you threaded it through the optic block, set the computer to capture through the serial port and then pulled the tape through.”

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

How to build an Uno-based 3D scanner



Till Handel (aka alicedownthecoffeepot) has published a detailed paper describing how to build a relatively inexpensive 3D scanner using an Atmel-based (ATmega328 MCUArduino Uno board and assorted spare parts, such as those scavenged from old printers and laptops.

As HackADay’s James Hobson reports, the Uno-equipped platform is capable of scanning 360° around itself at distances from 0.3 – 5m, making it a perfect fit for scanning rooms.

“It uses a line laser and a webcam mounted on an arm driven by a stepper motor, which looks like it’s out of an old optical drive,” Hobson explains.

“[Meanwhile], an Arduino Uno and an A4988POW stepper driver control the system.”

According to Hosbon, Handel’s 3D scanner is similar to others on the market, with a line laser providing a 2D profile/outline of the object being scanned that the camera picks up.

“As the system (or object) rotates, new profiles are recorded and sewn together to form a complete 3D image,” says Hobson.

“To increase the resolution and accuracy of the scanner, you can always [use] a better camera.”

Interested in learning more? You can check out Till Handel’s blog post here and detailed paper (published under GPLv3) here.

Video: This giant LED Tamagotchi hearts Atmel



The Tamagotchi (たまごっち?) is a handheld digital pet, originally designed in Japan by Akihiro Yokoi of WiZ and Aki Maita of Bandai way back in 1996. According to Wikipedia, well over 76 million Tamagotchis have been sold world-wide.

Image Credit: Wikipedia

The majority of Tamagotchis are housed in a small egg-shaped computer with an interface (typically) consisting of three buttons, although the number of buttons may vary.

However, a Maker by the name of Vadim recently decided to create a unique, desktop-sized Tamagotchi using a spare LED matrix and an Atmel ATmega328P microcontroller (MCU) with an Arduino bootloader.

As HackADay’s James Hobson reports, the LED matrix comprises four 8×8 LED modules with four shift registers (74HC595) and two Darlington transistor arrays to take the current.

“This is because the 256 LEDs need to be multiplexed down to 32 IO’s (16 rows + 16 columns),” he explained.

After the hardware was deemed operational, Vadim started work on the coding side of things, writing the entire game from scratch.

“While it’s not that complex it’s still an impressive amount of effort that went into this desktop- sized Tamagotchi!” Hobson added.

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

Uno power this two-axis solar tracker

Back in 2011, Jay Doscher had his power unexpectedly cut for 12 hours. After dealing with a refrigerator full of spoiled food, flashlights with dead batteries and a lack of candles, Doscher decided he needed to be better prepared for the next time the electricity went out.

His goal? To build a fully automated, portable solar tracking unit capable of automatically following the sun to optimize solar collection for those inevitable off-the-grid days.

As HackADay’s James Hobson notes, two-axis solar tracking units can help increase daily output by approximately 30%.

“Doscher’s makes use of a 12V gear reduced motor to provide panning and a linear actuator with positional tracking to control the tilt. To track the sun he’s got a digital compass and an Adafruit Ultimate GPS breakout board,” Hobson explained.

“To control it all he’s using is an [Atmel-powered] Arduino Uno (ATmega328 MCU). It’s a very slick and well engineered system and [Jay’s] hoping to spread it around the world — the entire thing is open source.”

Interested in learning more? You can check out Doscher’s tracker build log here and the relevant files on his GitHub repository here.

Video: Mega + Uno drives this 8X8X8 cube invader



Anred Zynch recently debuted a massively slick 8x8x8 LED cube — configured as a Space Invaders style game with a Playstation 1 controller.

According to Hackaday’s James Hobson, the cube is powered by an Arduino Mega (ATmega2560) which is tasked with driving the 512-LED array. 

Meanwhile, an Arduino Uno (ATmega328) is responsible for generating sound effects during gameplay.

Aside from the two Atmel based Arduino boards, key cube components include:

  • 512x LEDs
  • 10x Silver plated wire 0.8mm for sinkers and LED grid
  • 2x Breadboard 160×100 H25PR160 (sinkers)
  • 1x 100 Ohm resistor
  • 1x Speaker 8 Ohm
  • 2x resistor between 1,5 K and 47 K
  • 1x switch 2 or 3-positions
  • 1x or 2x 10K ohm resistor

Zynch’s cube — recently surfaced on Instructables — was reportedly inspired by a number of cube projects, including Chr’s and yes, the Borg cube by Das-Labour.

Interested in learning more? You can find additional information, along with a full parts breakdown on the project’s official page here.

DIY curved display with an Arduino Mega

A Maker by the name of Marin Davide has designed a DIY curved display with an Atmel-powered Arduino Mega (ATmega1280), nichrome wire and thermochromic liquid crystal ink.

According to James Hobson of HackADay, the current prototype uses a sheet of plastic coated in thermochromic ink – curved on an MDF frame.

“To display digits, Davide created tiny segments of the 7-segment display by wrapping the nichrome wire around pieces of cardboard, which then have been glued to the back of the display,” Hobson explained.

Meanwhile, Davide noted that although the prototype shows a 7-digit display, the detailed build guide can be easily modded to create a small dot-matrix display.

“The working prototype uses a sheet material printed with thermochromic liquid crystal ink,” Davide wrote in an official Design News description.

“It changes color (bright blue) when heated above 27C. Nickel-chrome wire is used to heat the segments and everything is controlled by an Arduino Mega board.”

The DIY curved display was made with 4mm Mdf, cut with a CNC, although this can also be done by hand. In addition, Davide used a 24V DC power supply, converted to 20Vdc with a KIA7820A. A 1000uF capacitor reduces noise on the 24V line, while a 220uF reduces noise on the 20V line. Last, but certainly not least, the Atmel-based Arduino is USB powered from the PC.

Interested in learning more about building a DIY curved display with an Atmel-based Arduino Mega? You can check out HackADay’s coverage here, the Design News article here and a detailed build tutorial (PDF) here.