Tag Archives: uno

Building a low-cost flow meter for river studies

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Scientific equipment is notoriously expensive, and for schools, there are often monopolies on which suppliers can provide it. Eben Farnworth wanted to do something about this problem. His design for an open flow meter only costs around $60 USD, which pales in comparison to the typical price tag of $1,000.  

Flow meters are great tools to measure how quickly a liquid (typically water or air) passes through a certain area. By using a propeller inside of an enclosure with a known diameter, the amount of liquid per unit of time can be calculated, along with how fast it is going. Farnworth’s design employs a DN80 water sensor, an Arduino Uno, and a 2.4″ TFT touchscreen.

The case houses all the electronics plus a battery for power. Then at the bottom of the device is a port for plugging in the flow sensor itself. After a bit of calibration, Farnworth was able to get the display to show the flow of a river with impressive accuracy.

To read more about how this flow meter was engineered, check out Farnworth’s project write-up.

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Arduino-controlled gas mixing device fills DIY laser tubes

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Lasers come in two varieties: solid-state and gas tube. As the name suggests, the latter types contain gas. That is a mixture of gas in precise proportions. To fill his DIY laser tube, Cranktown City built an Arduino-controlled gas mixer.

This device has an Arduino Uno board that drives three relay modules. The first relay switches power to a gas pump, the second relay controls an output valve, and the third relay controls an input valve. A push button starts the pumping process. The pump turns on and the input valve opens. Gas from a storage tank is pumped into an inflatable bag. Once the bag is full, as detected by a limit switch, the two valves flip and the gas pumps into the laser tube.

Cranktown City knows the exact volume of the inflatable bag, so he knows how much gas has been pumped into the laser tube each time the device runs. Like mixing a cocktail, this lets him “pour” each part of the gas mixture into the laser tube until he ends up with the correct proportions.

The gas pump, Arduino, relays, and inflatable bag are all enclosed within a heavy duty case made from steel sheet cut on a plasma table. The resulting mixer is portable and robust enough to stand up to abuse of a shop environment. With this device, Cranktown City can continue with developing his DIY laser tube — a project we can’t wait to see completed.

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Playing Connect Four against a mini-golfing AI opponent

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Have you dreamed of combining the two incredible activities mini-golf and Connect Four together into the same game? Well one daring maker set out to do just that. Bithead’s innovative design involves a mini-golf surface with seven holes at the end corresponding to the columns. The system can keep track of where each golf ball is with an array of 42 color sensors that are each connected to one of seven I2C multiplexers, all leading to a single Arduino Uno

The player can select from six distinct levels of AI, all the way from random shots in the dark to Q Learning, which records previous game-winning moves to improve how it plays over time. It can putt by first loading a golf ball into a chamber and then spinning up a pair of high-RPM motors that launch it. For the human player, there is a pair of dispensers on the left that give the correct color of ball. 

The entire system runs on an Intel NUC that hosts the game which was written in C#. There’s a large 22″ touchscreen at the front that is mounted at eye-level for easy interactions. Although it took Bithead nearly 18 months and $3,500, the end result is spectacular.

Be sure to check out his great write-up, which has a couple of demonstration videos and a build log. 

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Allen Pan’s Arduino-controlled microwave only works while gaming

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Microwave ovens have been the peak of convenient cooking since the 1960s, and nobody appreciates that convenience more than gamers. Normally you would microwave some pizza rolls between Call of Duty death matches, but Allen Pan decided to make gaming a more integral part of the cooking process for his most recent project.

This is a microwave oven that will only cook food while an attached game console is in use. That console is a generic all-in-one handheld with many built-in games, most of which are knock-offs or in the public domain. If a Hot Pocket requires three minutes of microwave cooking, then Pan has to play one of those games for a full three minutes or risk biting into an icy center.

Pan used an Arduino Uno board to monitor a microphone placed in front of the console’s speaker. The console only outputs audio while a game is in play, so this was a reliable way to determine if the user is actively playing or if they have walked away.

If the Arduino detects sound, then it will turn on a relay in the microwave oven. Pan hardwired the microwave oven so that any time it receives power, the microwave emitter will run. All Pan needs to do is pop some food in the microwave and start playing a game. So long as his thumbs don’t get tired, he can heat up whatever treat he craves.

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This auto-adjusting PVC system lifts hand sanitizer to the perfect height

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You’ve probably seen hand sanitizer stations popping up all over the place. While this seems to be a good thing, if you’re not exactly average height-wise, it’s likely they weren’t exactly designed for you. As a way to help both tall and short, and especially kids whose height varies considerably, Jegatheesan Soundarapandian has come up with an auto-adjustable stand.

The device, which is made from PVC pipe, measures your size using an ultrasonic sensor. A platform is then pulled into position via a stepper motor and string, under the control of an Arduino Uno and CNC shield. This presents you with hand sanitizer (or whatever else is needed) at a level customized just for you.

Code and plenty of additional information is available in Soundarapandiann’s Instructables post, along with a simple “bonus” contactless dispenser module build.

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Creating an over-engineered random number generator Arduino shield

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Often when working with Arduino projects, you’ll need to generate a random number. There’s a random() function built into the IDE that works acceptably in many cases, but maker_ATOM wanted to take things to the next level, creating an “over engineered true random value generator.”

This device sits on top of an Arduino Uno as a shield, and features input from a floating pin a seed value. It adds light input as a second seed value with an LDR, and ambient noise via a microphone as a third value. These are used to choose from an array of Pi digit values, which are also random, revealing outputs on its OLED display at the push of a button that would be exceedingly difficult to predict! 

More details on the project can be found in maker_ATOM’s Instructables post.