Bar Mixvah is a DIY robot bartender

Yu Jiang Tham recently debuted a DIY drink mixing robot aptly dubbed the “Bar Mixvah.”

The platform is built around an Atmel based Arduino Nano (ATmega328 MCU) paired with five 12V peristaltic pumps. On the software side, Yu Jiang employs the MEAN stack (MongoDB, Express.js, Angular.js, Node.js) and jQuery for the frontend and backend, respectively.

Additional key hardware specs include:

• 11x 5/16″ steel square 12″ rods
• Clear tubing
• 5x TIP120 w/diodes
• 400-point breadboard and jumper wire
• 5x 2.2kOhm resistor
• 4x #6-32 2″ machine screws
• 12V power supply rated at (or greater than) 1.5A – or you can use an old laptop power supply (as long as it’s 12V DC).
• 5.5mm x 2.1mm coaxial power connector (female) – or if you’re using a laptop power supply, 5.5mm x 2.5mm
• Male pin connectors
• Female housing for the male pin connectors

“Bar Mixvah is designed to use a system of 5 peristaltic pumps that are switched by 5 bipolar junction transistors (TIP120), all controlled by an Arduino, which itself is controlled by the Johnny-Five package on the node.js/express web server that is running on your laptop/Windows tablet,” Yu Jiang explained in a recent blog post.

“Having it on a web server allows users to order from any device, be it a phone, tablet, or other laptop that can connect to your WiFi access point’s internal network. Practicality-wise, maybe it’s not necessary. However, in my experience, people seem to enjoy ordering from a tablet that they’re holding in their hands more than a stationary screen attached to the robot.”

Interested in learning how to build your own DIY Bar Mixvah? You can check out the project’s official page here.

Nano tech could store power in cables, clothes

Professor Jayan Thomas and Ph.D. student Zenan Yu have developed an innovative method of transmitting and storing electricity in a single lightweight copper wire.

According to UCF Today (University of Central Florida), the technology could ultimately allow individuals to power their MP3 players, smartphones and tablets using the fabric of their jackets. 

Indeed, by being able to store and conduct energy on the same wire, heavy, space-consuming batteries may very well become an outdated remnant of the past.

“It’s an interesting idea. When we did it and started talking about it, everyone we talked to said, ‘Hmm, never thought of that. It’s unique,'” said Thomas. 

”We take it step by step. I love getting to the lab everyday, and seeing what we can come up with next. Sometimes things don’t work out, but even those failures teach us a lot of things.”

As Thomas notes, while copper wire may be the starting point, special fibers could eventually be developed with nanostructures to conduct and store energy.

The current model involves a single copper wire equipped with a sheath of nanowhiskers grown on the outer surface of the copper wire. 

The whiskers were subsequently treated with a special alloy, which created an electrode.

However, two electrodes were required to handle the energy storage, so the researchers created another by wrapping a thin plastic sheet around the whiskers using a metal sheath (after generating additional nanowhiskers). 

The layers were then glued together with a special gel. Because of the insulation, the inner copper wire retains its ability to channel energy, with the layers around the wire independently storing powerful energy.

Simply put, Thomas and his team managed to create an effective supercapacitor on the outside of the copper wire.

Although more research is required, the technique has the potential to be adapted for a wide range of applications. For example, flexible solar cells paired with the above-mentioned fibers could be used to design a jacket capable of powering various electronic devices.

Designing an Arduino-based programmable load

A programmable load is defined as a type of test equipment or instrument tasked with emulating DC or AC resistance loads normally required to perform functional tests of batteries, power supplies or solar cells.

According to Wikipedia, the platform allows tests such as load regulation, battery discharge curve measurement and transient tests to be fully automated – while load changes for these tests can be made without introducing switching transient that might alter the measurement or operation of the power source under test.

Recently, a Maker by the name of Jasper designed an Arduino-based programmable electric load using an Atmel-powered Nano (ATmega328 MCU).

“The load can be programmed, and the voltage and current are measured. You can set a constant current (CC), a constant power (CP), or a constant resistance (CR) load by simply typing it in to the Arduino Serial Monitor,” Jasper explained in a detailed blog post.

“The circuit is designed for up to 30V, 5A, and 15W. An opamp, a mosfet, and a small sense resistor form the constant current circuit. The current is set using a DAC. Two other opamps measure the power supply voltage and the current. The circuit is powered from the Arduino USB voltage.”

Aside from the Atmel-based Arduino Nano, key project components include:

• Custom designed PCB ($23)
• 2x 15pins 0.1″ pitch female header connectors ($2)
• AD8608 Rail-to-rail opamps ($3)
• MCP4725 DAC ($3)
• IRLZ44Z N-channel MOSFET ($2)
• SK 129 38mm Heat sink ($1)
• 0603 resistors and capacitors ($2)
• Screw terminal ($1)

“I chose to use an Arduino Nano board because it is small, cheap, easily interchangeable, it has a power supply that can be used to supply other circuits, and it can easily be programmed with the Arduino IDE,” Jasper continued.

“The Arduino is placed on female header connectors on the board. I chose to use the same DAC as on Adafruit and Sparkfun DAC breakout boards. The DAC can be supplied from 5V and the the output voltage is rail-to-rail. A description for using the MCP4725 DAC and library with Arduino can be found here on the Adafruit website. The DAC connects to the Arduino using I2C.”

On the software side, Jasper uses the the Arduino Serial Monitor to set the mode and value.

“For example, you can type ‘cc100’ to set a 100mA current, ‘cp1000’ to set a 1000mW power, and ‘cr100’ to set a 100 Ohm resistance. In overload condition, when the nominal power supply voltage drops, the CC circuit tries to maintain the current. This leads to an even further voltage drop and finally in a short circuit. In CP mode, the Arduino measures the voltage and adjusts the current so that the power remains constant,” he added.

“This is handy for testing power supplies designed to deliver a constant power. In CR mode, the Arduino measures the voltage and adjusts the current so that the resistance remains constant. This is handy if you want to simulate a resistor connected to the power supply – especially if you don’t have a box of power resistors of all kinds of values.”

Interested in learning more? You can check out Jasper’s Electric Load here.

Hacking Keepons with an Arduino Board

Keepon Pro – originally designed by scientists studying social development – is a “friendly” mini-robot that interacts with children. BeatBots and UK-based toy company Wow! Stuff offers a low-cost version of the Pro, although it lacks the ability to be teleoperated.

Recently, BeatBots co-founder Marek Michalowski co-authored an article in Makezine describing how to connect an Atmel-powered Arduino Nano board to My Keepon’s electronics, allowing users to control the ‘bot using just about any sensor, device or interface.

“The basic principle of this hack is to send commands to the microcontrollers inside My Keepon over the I2C bus. I2C is a two-wire serial interface commonly used for communication between embedded systems and peripherals (wikipedia.org/wiki/I2C),” Michalowski explained.

“We’ve provided access to all commands for setting motor speeds and positions, playing sounds, and retrieving information about audio perception, motor EMF and encoder positions. It’s a straightforward procedure, and you’ll easily be able to impress other Keepon fans with your new dance choreographies, Kinect mash-ups and Wiimote-control demos.”

Michalowski also noted that Makers can choose to mod the ‘bot in a basic fashion (with only a single additional hole drilled into the cylindrical base) or go with a more advanced option by installing the Arduino Nano board (ATmega328) inside the battery compartment, running the USB cable directly into the base and powering My Keepon with an adapter.

“[However], if you want to continue powering the My Keepon with batteries, or if you plan to use Arduino Uno/Mega shields (for wireless communication, additional sensors or actuators, etc.), you’ll probably want to “backpack” the components on the base,” he added.

Interested in learning more about hacking Keepons with an Arduino Board? You can check out the original Makezine article here.

Building an Arduino-based Sieve of Eratosthenes

The Sieve of Eratosthenes is a simple, ancient algorithm for finding all prime numbers up to any given limit. The algorithm does so by iteratively marking as composite the multiples of each prime, starting with the multiples of 2.

Photo Credit: Wikipedia

According to Wikipedia, the multiples of a given prime are generated as a sequence of numbers starting from that prime, with constant difference between them which is equal to that prime. This is the sieve’s key distinction from using trial division to sequentially test each candidate number for divisibility by each prime.

Recently, a Maker by the name of Darkmoonsinger built a modern-day Sieve of Eratosthenes using an LED matrix and an Atmel-powered Arduino.

“My little sister is finishing up her graduate degree in mathematics education this year, aiming to teach high school maths and I wanted to give her something besides just a grocery store gift card for her birthday. So I decided to make an Arduino-based demonstration of the Sieve of Eratosthenes, the prime number derivation sieve, that she can set on her desk and show her students,” Darkmoonsinger explained in a blog post about the project.

“First I bought myself an LED matrix and an 8-digit LED display driver (MAX7219) and soldered that all together and popped the LED matrix on. I hooked it up to my Arduino and ran some simple test code to make it run numbers (the original intention for the driver). Figured out how to address each LED individually. Then [I] got my Arduino Nano involved and got it breadboarded, wrote up the algorithm and got that going. [I then] soldered the whole thing to some stripboard, which meant I was in business.”

With the hardware side of things complete, Darkmoonsinger designed and 3D printed a slick enclosure for the Arduino-powered Sieve of Eratosthenes. Pretty cool, eh? No doubt Greek mathematician Eratosthenes of Cyrene would agree!

Interested in learning more? Be sure to check out Darkmoonsinger’s official Eratosthenes project page here.