Innovating A Backyard Solar Battery System

Ever on the lookout for creative applications for tech, [Andres Leon] built a solar powered battery system to keep his Christmas lights shining. It worked, but — pushing for innovation — it is now capable of so much more.

The shorthand of this system is two, 100 amp-hour, deep-cycle AGM batteries charged by four, 100 W solar panels mounted on an adjustable angle wood frame. Once back at the drawing board, however, [Leon] wanted to be able track real-time statistics of power collected, stored and discharged, and the ability to control it remotely. So, he introduced a Raspberry Pi running Raspbian Jessie Lite that publishes all the collected data to Home Assistant to be accessed and enable control of the system from the convenience of his smartphone. A pair of Arduino Deuemilanoves reporting to the Pi control a solid state relay powering a 12 V, 800 W DC-to-AC inverter and monitor a linear current sensor — although the latter still needs some tinkering. A in-depth video tour of the system follows after the break!

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Reverse Swear Box Curses (For) You

If you are running out of swear words to comment the magic smoke coming from your electronics, [Howard] has just the right weekend project for you: The reverse swear box. Most swear boxes would have you drop in a coin as penance for uttering your choice phrases. Instead, at the touch of a button, this obscure but classy device randomly suggests a four letter swear word and displays it on a 14-segment LED display for immediate or later use.

It’s built upon an ATmega168 and only requires a minimum of external components. The schematics and firmware for this project are freely available on the project page. There’s also an extremely profane header file, packed with 37 case-insensitive four-letter words you may not actually want to include in your toolkit. On the other hand, many of these words score intimidatingly well at Scrabble.

Hackaday Prize Entry: Shakelet

A person who is deaf can’t hear sound, but that doesn’t mean they can’t feel vibrations. For his Hackaday Prize entry, [Alex Hunt] is developing the Shakelet, a vibrating wristband for that notifies hearing impaired people about telephones, doorbells, and other sound alerts.

To tackle the difficulty of discriminating between the different sounds from different sources, [Alex’s] wants to attach little sound sensors directly to the sound emitting devices. The sensors wirelessly communicate with the wristband. If the wristband receives a trigger signal from one of the sensors, it alerts the wearer by vibrating. It also shows which device triggered the alert by flashing an RGB LED in a certain color. A first breadboard prototype of his idea confirmed the feasibility of the concept.

After solving a few minor problems with the sensitivity of the sensors, [Alex] now has a working prototype. The wristband features a pager motor and is controlled by an ATMEGA168. Two NRF24L01+ 2.4 GHz wireless transceiver modules take care of the communication. The sound sensors run on the smaller ATTiny85 and use a piezo disc as microphone. Check out the video below, where Alex demonstrates his build:

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Hackaday Links: November 8, 2015

[Burt Rutan] is someone who needs no introduction. Apparently, he likes the look of the Icon A5 and is working on his own version.

Earlier this week, the US Air Force lost a few satellites a minute after launch from Barking Sands in Hawaii. This was the first launch of the three stage, solid fueled SPARK rocket, although earlier versions were used to launch nuclear warheads into space. There are some great Army videos for these nuclear explosions in space, by the way.

[Alexandre] is working on an Arduino compatible board that has an integrated GSM module and WiFi chip. It’s called the Red Dragon, and that means he needs some really good board art. The finished product looks good in Eagle, and something we can’t wait to see back from the board house.

The Chippocolypse! Or however you spell it! TI is declaring a lot of chips EOL, and although this includes a lot of op-amps and other analog ephemera (PDF), the hi-fi community is reeling and a lot of people are stocking up on their favorite amplifiers.

[Jeremy] got tired of plugging jumper wires into a breadboard when programming his ATMega8 (including the ‘168 and ‘328) microcontrollers. The solution? A breadboard backpack that fits right over the IC. All the files are available, and the PCB can be found on Upverter.

In case you haven’t heard, we’re having a Super Conference in San Francisco later this week. Adafruit was kind enough to plug our plug for the con on Ask an Engineer last week.

Automated Robotic Target Practice

Fan of shooting things? Jealous of proper shooting ranges? Why not build your own automated target practice rig with a few servos and an ATMega168?

[Cowboy Bob] of Making Stuff decided he needed a practice target, and wanted to make it a bit more interesting than throwing up some beer cans on a fence. He’s created a highly durable 10-target “Robo-Target” which can be remote controlled or automated.  A thick piece of 1/4″ angle steel makes up the main frame of it, so if you’re practicing with hand guns it’ll take the abuse. If you’re just using  an air soft or paintball gun you probably don’t need to make it this beefy.

Five servo motors swing paper five targets back and forth on 3D printed swing arms — and since each target has a front and a back side, it gives you 10 different things to shoot at. In challenge mode it’ll even show you two targets at a time which will require you to quickfire in order to get both!

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Open Source Power Line Communication

Power Line Communication Filtering


Since we all have wires running throughout our houses to provide mains power, there’s a number of devices that piggyback on mains lines for communication. For his thesis project, [Haris Andrianakis] developed his own power line communication system.

The basic principle of the system is to inject a signal onto the power lines at a much higher frequency than the 50 or 60 Hz of the AC power itself. Using both active and passive filters, the signal can be separated from the AC power and decoded. This system uses frequency-shift keying to encode data. This part is done by a ST7540 modem that’s designed for power line applications. The modem is controlled over SPI by an ATmega168 microcontroller.

[Haris]’ write up goes into detail about some of the challenges he faced, and how to protect the device from the high voltages present. The final result is a remote display for a weigh scale, which communicates over the power line. Schematics, PCB layout, and software are all available.

Energy-Saving Fireplace Thermostat

[Andrian] has a boiler stove that heats water and sends it to a radiator. As the fireplace heats the water in a boiler a temperature sensor opens the a valve to send the warm water to the radiator. The radiator sends its cool water back to the boiler to be reheated. The valve is slow, so before the boiler can send all the water to the radiator, it’s getting cool water back causing the valve to close while the heat is built back up. To prevent the valve from working so hard and wasting energy, [Andrian] designed a better thermostat to control the valve operation.

The thermostat uses one LM85 temperature sensor to check the water in the boiler and another one for the ambient temperature. Once the boiler water reaches the desired temperature, the valve is opened via relay. The system waits for half an hour and then checks the boiler temperature again. The brains of this operation is an ATMega168 with a 32.768kHz crystal as the RTC. Code and PCB files are available in his repo.

We love to see these types of hacks that challenge the status quo and increase the efficiency of appliances. We applaud you, [Andrian], for turning your dissatisfaction into a positive plan of action and for sharing your experience with the rest of us!

If you want to up the eco-friendliness of heating water a bit, you could heat the water with a compost heap.