A wise man once said “If all you’ve got is a cute desktop compressor and some solenoid valves, everything looks like a robotic harmonica.” Or maybe we’re paraphrasing. Regardless, [Fabien-Chouteau] built a pneumatic, automatic harmonica music machine.
It’s actually an offshoot of his other project, a high-speed candy sorting machine. There, he’s trying to outdo the more common color-sensor-and-servo style contraptions by using computer vision for the color detection and a number of compressed-air jets to blow the candy off of a conveyor belt into the proper bins.
Continue reading “Automatic Pneumatic Harmonica”
Smart phones are great. So great that you may find yourself distracted from working, eating, conversing with other human beings in person, or even sleeping. [Digitaljunky] has this problem (not surprising, really, considering his name) so he built an anti-procrastination box. The box is big enough to hold a smart phone and has an Arduino-based time lock.
The real trick is making the box so that the Arduino can lock and unlock it with a solenoid. [Digitaljunky] doesn’t have a 3D printer, so he used Fimo clay to mold a custom latch piece. A digital display, a FET to drive the solenoid, and a handful of common components round out the design.
Continue reading “Avoid Procrastination with this Phone Lock Box”
[Bob] built this simple device that can best be described as an electronic float valve. He was wasting a lot of water from overflowing water troughs and buckets around his farm. He would usually put the hose in the container, turn on the water valve and carry on with his work. By the time he remembered to come back, the area would be flooded. It’s obvious that there’s many different ways to solve a problem. For example, a simple mechanical float valve might have worked, but it’s not horse friendly and liable to get damaged soon.
The electronics is unabashedly minimal. An ATtiny85 controls a relay via a common variety NPN transistor. The relay in turn switches the solenoid valve. A push-button tells the microcontroller to start the water flowing, and when the water level gets high enough that it touches two hose clamps, the micro shuts it off again.
There’s some ghetto engineering going on here. The electronics is driven by a 9V battery, although the relay and the solenoid valve that [Bob] used are both rated for 12V. He’s not even using any sort of voltage regulation for the ATtiny, but instead dropping the voltage with a resistor divider. (We wonder about battery life in the long run.)
He built all of it on perf board and stuffed it inside a small enclosure, with two wires coming out for the level sensor and another two for the solenoid, and it seems to work. Check the video below where [Bob] walks through his build.
While some may point out the many short comings in this build, [Bob] found the one solution that works for him. Sometimes the right solution is what you’ve got on hand, and we’re glad he’s hacking away and sharing his work. And check out this wireless water level sensor that he built some time back.
Continue reading “Electronic float valve keeps the horse’s feet dry”
We’ve seen quite a few clocks that write the time out with a pen or marker. If you think about it, this really isn’t a great solution; every whiteboard marker will dry out in a day or two, and even if you’re using a pen, that’s still eventually going to run out of ink.
[ekaggrat] wanted a drawing clock that didn’t have these problems, and after taking a look at a magnetic drawing board, was struck with inspiration. The result is a clock that will perpetually write the time. It’s a revision of one of his earlier builds and looks to be much more reliable and mechanically precise.
A clock that writes time needs some sort of surface that won’t degrade, but can be written to over and over again. Whiteboards and glass won’t work, and neither will anything with ink. The solution to this problem was found in a ‘magnetic writing board’ or a Magna Doodle. These magnetic writing boards have a series of cells encapsulating iron filings. Pass a magnet over one side of the board, and a dot of filings appear. Pass a magnet over the opposite side of the board, and the filings disappear.
[ekaggrat]’s time-writing robot consists of a small Magna Doodle display, a robotic arm controlled by two stepper motors, and two solenoids on the end of the arm. The kinematics come from a helpful chap on the RepRap forums, and with the ATmega644 and two stepper drivers, this clock can write the time by altering the current flowing through two solenoids.
A video is the best way to experience this project, and you can check that out below.
Continue reading “Robot Clock Writes Time Over and Over and Over”
Radial engines are just plain cool – it’s inarguable that any tech that originated with early aviation is inherently awesome. But, what do you do when you want to build a radial engine in your dorm where a combustion engine would be inadvisable? For University of Washington students [Jeffrey Weng] and [Connor Lee] the answer was to power it with solenoids in place of the pistons.
The easiest way to approach a project like this would have been to use a microcontroller. A simple program running on an Arduino could have easily provided the timing to switch power to each solenoid in succession. [Jeffrey Weng] and [Connor Lee], however, took a much more interesting approach by controlling timing via a simple distributor. This works in the same way a spark distributor on a combustion engine would have worked, except it’s actually providing the power to actuate the solenoids instead of providing just an ignition spark.
Also impressive is what they were able to accomplish with such basic tools. Those of us who are lazy and have access to more expensive tools would have just 3D printed or CNC cut most of the parts. Either [Jeffrey Weng] and [Connor Lee] didn’t have access to these, or they wanted to increase their machining street cred, because they created all of the parts with simple tools like a band saw and drill press. We’ve seen some beautiful engine projects before, but what this build lacks in objective beauty it makes up for in ingenuity.
Continue reading “Radial Solenoid Engine is Undeniably Cool”
There are many different ways to keep your plants watered on a schedule. [Luca Dentella] just created a new one by building the irrighino watering system. He used standard off the shelf, hardware to keep it simple. Irrighino is a complete watering system based on the Arduino Yun, featuring a user friendly AJAX interface. This allows scheduling in a manner similar to creating appointments in Outlook. It’s also possible to manually control the various water solenoids. The code is fully customizable and open source, with code available from [Luca’s] github repository. The web interface is divided in to three tabs – “runtime” for manual control, “setup” to configure the scheduling, and “events” to view system logs.
The Arduino Yun activates solenoid valves via a relay shield. A switch panel has indicator Status LED’s and three position switches. These allow the outputs to be switched off or on manually, or controlled via the Yun when in auto mode. [Luca] describes how to read three states of the switch (On-Off-On) when connected to a single analog input of the Arduino. He’s also got another tutorial describing how to connect a USB WiFi adapter to the Yun. This is handy since the Yun is mounted inside an enclosure where the signal strength is very weak. While the Yun has on-board WiFi, there is no possibility to attach an external antenna directly to the test SMA socket.
One interesting part is the commercial rain sensor. It’s a switch surrounded by a spongy material. When this material absorbs rain water, it begins to expand and triggers the switch. The Arduino sees the sensor as a simple digital input.
Check a short demo of his system in the video after the break.
Continue reading “Irrighino, an Arduino Yun Based Watering System”
[Kirk Kaiser] isn’t afraid to admit his latest project a bit strange, being a plant-controlled set of robotic bongos. We don’t find it odd at all. This is the kind of thing we love to see. His project’s origins began a month ago after taking a class at NYC Resistor about creating music from robotic instruments. Inspired to make his own, [Kirk] repurposed a neighbor’s old wooden dish rack to serve as a mount for solenoids that, when triggered, strike a couple of plastic cowbells or bongo drums.
A Raspberry Pi was originally used to interface the solenoids with a computer or MIDI keyboard, but after frying it, he went with a Teensy LC instead and never looked back. Taking advantage of the Teensy’s MIDI features, [Kirk] programmed a specific note to trigger each solenoid. When he realized that the Teensy also had capacitive touch sensors, he decided to get his plants in on the fun in a MaKey MaKey kind of way. Each plant is connected to the Teensy’s touchRead pins by stranded wire; the other end is stripped, covered with copper tape, and placed into the soil. When a plant’s capacitance surpasses a threshold, the respective MIDI note – and solenoid – is triggered. [Kirk] quickly discovered that hard-coding threshold values was not the best idea. Looking for large changes was a better method, as the capacitance was dramatically affected when the plant’s soil dried up. As [Kirk] stood back and admired his work, he realized there was one thing missing – lights! He hooked up an Arduino with a DMX shield and some LEDs that light up whenever a plant is touched.
We do feel a disclaimer is at hand for anyone interested in using this botanical technique: thorny varieties are ill-advised, unless you want to play a prank and make a cactus the only way to turn the bongos off!
Continue reading “Play Robotic Bongos using your Household Plants”