Solar Panel System Monitoring Device Using Arduino

[Carl] recently upgraded his home with a solar panel system. This system compliments the electricity he gets from the grid by filling up a battery bank using free (as in beer) energy from the sun. The system came with a basic meter which really only shows the total amount of electricity the panels produce. [Carl] wanted to get more data out of his system. He managed to build his own monitor using an Arduino.

The trick of this build has to do with how the system works. The panel includes an LED light that blinks 1000 times for each kWh of electricity. [Carl] realized that if he could monitor the rate at which the LED is flashing, he could determine approximately how much energy is being generated at any given moment. We’ve seen similar projects in the past.

Like most people new to a technology, [Carl] built his project up by cobbling together other examples he found online. He started off by using a sketch that was originally designed to calculate the speed of a vehicle by measuring the time it took for the vehicle to pass between two points. [Carl] took this code and modified it to use a single photo resistor to detect the LED. He also built a sort of VU meter using several LEDs. The meter would increase and decrease proportionally to the reading on the electrical meter.

[Carl] continued improving on his system over time. He added an LCD panel so he could not only see the exact current measurement, but also the top measurement from the day. He put all of the electronics in a plastic tub and used a ribbon cable to move the LCD panel to a more convenient location. He also had his friend [Andy] clean up the Arduino code to make it easier for others to use as desired.

Laser-Cut Clock Uses Planetary Gear

[wyojustin] was trying to think of projects he could do that would take advantage of some of the fabrication tech that’s become available to the average hobbyist. Even though he doesn’t have any particular interest in clocks, [wyojustin] discovered that he could learn a lot about the tools he has access to by building a clock.

[wyojustin] first made a clock based off of a design by [Brian Wagner] that we featured a while back. The clock uses an idler wheel to move the hour ring so it doesn’t need a separate hour hand. After he built his first design, [wyojustin] realized he could add a planetary gear that could move an hour hand as well. After a bit of trial and error with gear ratios, he landed on a design that worked.

The clock’s movement is a stepper motor that’s driven by an Arduino. Although [wyojustin] isn’t too happy with the appearance of his electronics, the drive setup seems to work pretty well. Check out [wyojustin]’s site to see the other clock builds he’s done (including a version with a second hand), and you can peruse all of his design files on GitHub.

Looking for more clock-building inspiration? Check out some other awesome clock builds we’ve featured before.

Automated Pocky Dispenser

Sometimes, along comes a build project that is not so much a fail, as how not to do it. First off, some of us here had to look up what a Pocky is, never having heard, seen or tasted one – seriously. Once satisfied, we turned our attention to [Michael]’s Automated Pocky Dispenser. Took a while for us to figure out if it’s useful or not. But it’s a fun, quick project that [Michael] put together in around an hour using parts lying around in his office.

For those of you who’d like to know, a Pocky is a chocolate-coated biscuit stick, although you can also buy it in other flavors. You can grab one from a box, but maybe it tastes better when you dispense it by banging a big red button. [Michael] says he used  incredibly advanced construction techniques, but we leave it to our readers to decide on that. The key element of the build is the special “flexible coupling” that he built to transfer the rotation of the stepper motor to the dispensing mechanism. The rest of the build consists of an Arduino, stepper motor, driver, and giant red button. Special motor driving code ensures that the dispenser wiggles back and forth every time, preventing any stuck Pocky’s. And the Electronics are, well, hanging out for all to see. Happy with the success of his build, [Michael] is planning an upgraded version – to connect the Pocky Dispenser to the cloud for statistical gathering of office Pocky habits. He claims even Google does not have that data. To see the dispenser in action, check out the video below.

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3D Printed Fish Feeder

[Helios Labs] recently published version two of their 3D printed fish feeder. The system is designed to feed their fish twice a day. The design consists of nine separate STL files and can be mounted to a planter hanging above a fish tank in an aquaponics system. It probably wouldn’t take much to modify the design to work with a regular fish tank, though.

The system is very simple. The unit is primarily a box, or hopper, that holds the fish food. Towards the bottom is a 3D printed auger. The auger is super glued to the gear of a servo. The 9g servo is small and comes with internal limiters that only allow it to rotate about 180 degrees. The servo must be opened up and the limiters must be removed in order to enable a full 360 degree rotation. The servo is controlled by an Arduino, which can be mounted directly to the 3D printed case. The auger is designed in such a way as to prevent the fish food from accidentally entering the electronics compartment.

You might think that this project would use a real-time clock chip, or possibly interface with a computer to keep the time. Instead, the code simply feeds the fish one time as soon as it’s plugged in. Then it uses the “delay” function in order to wait a set period of time before feeding the fish a second time. In the example code this is set to 28,800,000 milliseconds, or eight hours. After feeding the fish a second time, the delay function is called again in order to wait until the original starting time.

Arduino Synth Guitar Really Rocks

[Gr4yhound] has been rocking out on his recently completed synth guitar. The guitar was built mostly from scratch using an Arduino, some harvested drum pads, and some ribbon potentiometers. The video below shows that not only does it sound good, but [Gr4yhound] obviously knows how to play it.

The physical portion of the build consists of two main components. The body of the guitar is made from a chunk of pine that was routed out by [Gr4yhound’s] own home-made CNC. Three circles were routed out to make room for the harvested Yamaha drum pads, some wiring, and a joystick shield. The other main component is the guitar neck. This was actually a Squire Affinity Strat neck with the frets removed.

For the electronics, [Gr4yhound] has released a series of schematics on Imgur. Three SoftPot membrane potentiometers were added to the neck to simulate strings. This setup allows [Gr4yhound] to adjust the finger position after the note has already been started. This results in a sliding sound that you can’t easily emulate on a keyboard. The three drum pads act as touch sensors for each of the three strings. [Gr4yhound] is able to play each string simultaneously, forming harmonies.

The joystick shield allows [Gr4yhound] to add additional effects to the overall sound. In one of his demo videos you can see him using the joystick to add an effect. An Arduino Micro acts as the primary controller and transmits the musical notes as MIDI commands. [Gr4yhound] is using a commercial MIDI to USB converter in order to play the music on a computer. The converter also allows him to power the Arduino via USB, eliminating the need for batteries.

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Arduino v. Arduino

Arduino LLC is suing Arduino Srl (the Italian version of an LLC). Sounds confusing? It gets juicier. What follows is a summary of the situation as we learned it from this article at (google translatrix)

Arduino LLC is the company founded by [Massimo Banzi], [David Cuartielles], [David Mellis], [Tom Igoe] and [Gianluca Martino] in 2009 and is the owner of the Arduino trademark and gave us the designs, software, and community support that’s gotten the Arduino where it is. The boards were manufactured by a spinoff company, Smart Projects Srl, founded by the same [Gianluca Martino]. So far, so good.

Things got ugly in November when [Martino] and new CEO [Federico Musto] renamed Smart Projects to Arduino Srl and registered (which is arguably a better domain name than the old Whether or not this is a trademark infringement is waiting to be heard in the Massachussetts District Court.

According to this Italian Wired article, the cause of the split is that [Banzi] and the other three wanted to internationalize the brand and license production to other firms freely, while [Martino] and [Musto] at the company formerly known as Smart Projects want to list on the stock market and keep all production strictly in the Italian factory.

Naturally, a lot of the original Arduino’s Open Source Hardware credentials and ethos are hanging in the balance, not to mention its supply chain and dealer relationships. However the trademark suit comes out, we’re guessing it’s only going to be the first in a series of struggles. Get ready for the Arduino wars.

We’re not sure if this schism is at all related to the not-quite-open-source hardware design of the Yun, but it’s surely the case that the company is / the companies are going through some growing pains right now.

Thanks [Philip Steffan] for the pointer to the MakeMagazin.DE article. (And for writing it.)

OK Google, Open Sesame

There are a myriad of modern ways to lock and unlock doors. Keypads, Fingerprint scanners, smart card readers, to name just a few. Quite often, adding any of these methods to an old door may require replacing the existing locking mechanism. Donning his Bollé sunglasses allowed [Dheera] to come up with a slightly novel idea to unlock doors without having to change his door latch. Using simple, off the shelf hardware, a Smartwatch, some code crunching and a Google Now app, he was able to yell “OK Google, Open Sesame” at his Android Wear smartwatch to get his apartment  door to open up.

The hardware, in his own words, is trivial. An Arduino, an HC-05 bluetooth module and a servo. The servo is attached to his door latch using simple hardware that looks sourced from the closest hardware store. The code is split in to two parts. The HC-05 listens for a trigger signal, and informs the Arduino over serial. The Arduino in turn activates the servo to open the door. The other part is the Google Now app. Do note that the code, as he clearly points out, is “barebones”. If you really want to implement this technique, it would be wise to add in authentication to prevent all and sundry from opening up your apartment door and stealing your precious funky Sunglasses. Watch a video of how he put it all together after the break. And if you’re interested, here are a few other door lock hacks we’ve featured in the past.

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