Goldilocks Climate Box Keeps Lager Fermentation Environment Just Right

September was warmish in many places around the world including [Ole]’s native Denmark. But that did not stop him from brewing lager flavored with plums from his own garden, and neither did his indifference to lagers in general.

Lager fermentation requires a consistent, low temperature. While many homebrewers might modify an electric refrigerator, [Ole] wasn’t interested in the cost of running a second one just for brewing beer. Instead, he built a climate box to work with the cool temperature in his garage. Starting with scrap wood from other projects, he lined the walls with polystyrene and put a layer of wood on the floor to help support the fermentation bucket.

Maintaining a consistent temperature in the box called for both heating and cooling. He pulled the Peltier from a 12V cooler meant to run off a car’s cigarette lighter, and used a spare ceramic heater that was lying around in case his primary reptile warmer went on the fritz.

An Arduino and a custom shield drive separate PID controllers for the Peltier and the heater. The shield has a temperature probe, and he extended the USB outside the climate box so the PIDs can be adjusted without disturbing the inside temperature. The schematic, board file, and code are all available in a zip you can get from his post.

The Peltier couldn’t quite compensate for the overly warm weather and the heat caused by the fermentation, but it was stable enough to produce a nice, plum-flavored lager he has dubbed Lektor Blom­mes malt­bol­che, which is a triple Danish pun he explains in the write-up.

Margarita Drip Infuser Ensures a Perfect Mix

In order to get a margarita just right, the various ingredients need to be mixed together quite vigorously to over-come the different viscosity of the fluids. Looking to create his own barbot of sorts, [TVMiller] decided to make a Margarita Drip Infuser to help make margaritas a bit easier.

Using various chem lab supplies, [TVMiller] has cobbled together something pretty awesome. The Infuser can take up to 8 different ingredients into its test tube reserves, and after the drink ingredients are programmed on the computer, the magic begins.

An Arduino Uno controls a bank of 8 relays which control small fluid solenoids, with each control pulse releasing just a single droplet of fluid. An LED for each valve is run in parallel adding a bit of a light show to the mixing experience. If that’s not enough, he’s also created a copper cooling coil to chill the drink as it is poured.

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BORAT: Bathroom Monitor for the Future

A recent company move has left [kigster] and his 35 coworkers in a frustrating situation. Their new building only has two single occupancy bathrooms. To make matters worse, the bathrooms are located on two different floors. Heading to one bathroom, finding it occupied, then running upstairs to find the second bathroom also occupied became an all to common and frustrating occurrence at the office.

It was obvious the office needed some sort of bathroom occupancy monitoring system – much like those available on commercial aircraft. [kigster] asked for a budget of about $200 to build such a system. His request was quickly granted it by office management. They must have been on their way to the bathroom at the time.

borat1[kigster] began work on BORAT: Bathroom Occupancy Remote Awareness Technology. The initial problem was detecting bathroom occupancy. The easiest method would be to use door locks with embedded switches, much those used in aircraft. Unfortunately, modifying or changing the locks in a rented office space is a big no-no. Several other human detection systems were suggested and rejected. The final solution was a hybrid. Sonar, Passive Infrared (PIR), and light sensors work in concert to detect if a person is in the bathroom. While we think the final “observer unit” is rather cool looking, we’re sure unsuspecting visitors to the office may be wondering why a two eyed robot is staring at them on the throne.

The display side of the system was easy. The entire system communicates with the venerable nRF24L01+ radio modules, so the display just needed a radio module, an arduino, and a way of displaying bathroom status. Two LED matrices took care of that issue.

We really like this hack. Not only is it a great use of technology to solve a common problem, but it’s also an open source system. BORAT’s source code is available on [kigster’s] github.

Want to know more about BORAT? Kigster is answering questions over on his thread in the Arduino subreddit.

Build Your Own Stand Alone Web Radio

If you’re the type who enjoys passing idle time by keeping up with podcasts or listening to web stations but don’t always want to occupy your laptop or tablet, this Arduino based radio player will provide a base station for tunes.

The Web Radio project by [Vassilis Serasidis] outlines in a pleasing amount of detail exactly how to wire up a short list of four modules. These including an Ethernet shield, LCD screen, MP3 decoder, and USB serial converter, with an Arduino Mini in order to bookmark and play fourteen of your favorite channels. His hand-soldered board couples everything into one neatly stacked package. The instructional video shows this off and he even explains how to locate your favorite stations on internet-radio.com and copy their port and IP number directly into an example sketch which is provided for use. If you’ve been wanting to build a self contained radio node for your desk free of extra baggage, this is a no-sweat project for both the hardware savvy and those more oriented with code writing.

If you’re going to build your own radio, it’s always cool to disguise your high-tech creation as something more rustic. Check out this project by [Dominic Buchstaller] for a great example of a vintage radio given a second calling.

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MacGyvered Optoisolator is a Great Introduction

Sometimes the best way to learn about a technology is to just build something yourself. That’s what [Dan] did with his DIY optoisolator. The purpose of an optoisolator is to allow two electrical systems to communicate with each other without being electrically connected. Many times this is done to prevent noise from one circuit from bleeding over into another.

[Dan] built his incredibly simple optoisolator using just a toilet paper tube, some aluminum foil, an LED, and a photo cell. The electrical components are mounted inside of the tube and the ends of the tube are sealed with foil. That’s all there is to it. To test the circuit, he configured an Arduino to send PWM signals to the LED inside the tube at various pulse widths. He then measured the resistance on the other side and graphed the resulting data. The result is a curve that shows the LED affects the sensor pretty drastically at first, but then gets less and less effective as the frequency of the signal increases.

[Dan] then had some more fun with his project by testing it on a simple temperature controller circuit. An Arduino reads a temperature sensor and if the temperature rises above a certain value, it turns on a fan to cool the sensor off again. [Dan] first graphed the sensor data with no fan hooked up. He only used ambient air to cool things down. The resulting graph is a pretty smooth curve. Next he hooked the fan up and tried again. This time the graph went all kinds of crazy. Every time the fan turned on, it created a bunch of electrical noise that prevented the Arduino from getting an accurate analog reading of the temperature sensor.

The third test was to remove the motor circuit and move it to its own bread board. The only thing connecting the Arduino circuit to the fan was a wire for the PWM signal and also a common ground. This smoothed out the graph but it was still a bit… lumpy. The final test was to isolate the fan circuit from the temperature sensor and see if it helped the situation. [Dan] hooked up his optoisolator and tried again. This time the graph was nice and smooth, just like the original graph.

While this technology is certainly not new or exciting, it’s always great to see someone learning by doing. What’s more is [Dan] has made all of his schematics and code readily available so others can try the same experiment and learn it for themselves.

Brushless Motor Controller Shield for Arduino

Brushless motors are ubiquitous in RC applications and robotics, but are usually driven with low-cost motor controllers that have to be controlled with RC-style PWM signals and don’t allow for much customization. While there are a couple of open-source brushless drivers already available, [neuromancer2701] created his own brushless motor controller on an Arduino shield.

[neuromancer2701]’s shield is a sensorless design, which means it uses the back-EMF of the motor for feedback rather than hall effect sensors mounted on the motor. It may seem strange to leave those sensors unused but this allows for less expensive sensorless motors to work with the system. It also uses discrete FETs instead of integrated driver ICs, similar to other designs we have covered. Although he is still working on the back-EMF sensing in his firmware, the shield successfully drives a motor in open-loop mode.

The motor controller is commanded over the Arduino’s serial interface, and will support a serial interface to ROS (Robot Operating System) in the future. This shield could be a good alternative to hobby RC controllers for robots that need a customizable open-source motor controller. The PCB design and source code are available on GitHub.

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Web Browser Pushes Arduino’s Limits

Some projects that we build fulfill a genuine need for a new piece of hardware or software that will make life easier or fix a common problem. Other projects, on the other hand, we do just because it’s possible to do. [Gilchrist] has finished work on a project that fits squarely in the second category: a web browser that runs exclusively on an Arduino Uno with an ethernet shield.

The Arduino can serve plain-text web pages to an attached LCD and can follow hyperlinks. User input is handled by a small joystick, but the impressive part of the build is on the software side. The Arduino only has 2KB of RAM to handle web pages, and the required libraries take up 20KB of memory, leaving only about 12 KB for the HTML parser/renderer and the LCD renderer.

The Arduino browser is a work in progress, and [Gilchrist] mentions that goals for the project include more robustness to handle poor HTML (the Hackaday retro edition loads flawlessly though), a terminal, and WiFi capabilities. To that end, maybe a good solution would be using the new ESP8266 chip to keep things small and inexpensive?