Beach Buddy Is A Boombox, Phone Charger, And Sunburn Warner

August 18, 2014 by Marsh 6 Comments

When you venture out onto the beach for a day in the sun, you’re probably not preoccupied with remembering the specifics about your sunscreen’s SPF rating—if you even remembered to apply any. [starwisher] suffered a nasty sunburn after baking in the sunlight beyond her sunscreen’s limits. To prevent future suffering, she developed The Beach Buddy: a portable stereo and phone charger with a handy sunburn calculator to warn you the next time the sun is turning you into barbecue.

After telling the Beach Buddy your skin type and your sunscreen’s SPF rating, a UV sensor takes a reading and an Arduino does a quick calculation that determines how long until you should reapply your sunscreen. Who wants to lug around a boring warning box, though?

[starwisher] went to the trouble of crafting a truly useful all-in-one device by modifying this stereo and this charger to fit together in a sleek custom acrylic enclosure. There’s a switch to activate each function—timer, charger, stereo—a slot on the side to house your phone, and an LCD with some accompanying buttons for setting up the UV timer. You can check out a demo of all the Beach Buddy’s features in a video below.

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Easy To Build Solar Pool Heater Saves Money And Keeps You From Freezing

August 7, 2014 by James Hobson 37 Comments

For those cool summer days it’s sometimes nice to have a heated pool — but usually pretty expensive too. Looking for a simpler solution [Martin] came up with his own solar pool heater for under $100!

He’s copied the basic design of a solar pool heater but managed to do it using fairly cheap parts from the hardware store. It consists of three 100′ lengths of 1/2″ drip irrigation hose, and the way he’s connected them is rather ingenious. Using a half inch piece of copper pipe and a blow torch, he was able to squeeze the pipe into one hose end and then the other for a permanent seamless connection. He then coiled the resulting hose into a large circle by interweaving string back and forth to keep its shape.

A 12V utility pump coupled with a timer allows water to sit in the hose under the sun for one hour, at which point it cycles the system for 10 minutes, pumping the warm water into the pool, and refilling itself with cool water from the bottom of the pool. This one is only made for a small above ground pool, but the design could easily be doubled or even tripled for larger pools. You could also throw in a PID temperature controller or even an Arduino to make it even better… but it sounds like it works quite well by itself with a timer.

Combine this with a compost-based hot water system for indoors and you’ll really be cutting the expense associated with your hot water needs!

Solar Energy Provides An Outlet For Hurricane-Related Woes

June 3, 2014 by Kristina Panos 96 Comments

Hurricane season in the US Atlantic region officially began on June 1st. While [mikesoniat] is hoping for a mild one in his Gulf Coast town, he’d like to be as prepared as possible in the event of a power outage. He’s been experimenting with solar power lately, and while he’d love to go all out with some hefty system that could keep all his appliances running, solar outlet he’s not quite ready for that kind of investment. While thinking about this dream system, he noticed all the phone jacks around his house that he hasn’t used for several years. After consulting the phone company and researching the capabilities of 22-26AWG POTS copper lines, he devised a solar-powered system to provide enough power to run lights, fans, and a couple of phone chargers.

At the heart of this hack are two 12V solar panels, two 12V batteries in a weatherproof junction box, and a 100W solar charge controller. He started by re-wiring Ma Bell’s junction box up to the panels with thermostat wire. After prying out the RJ11 jack panels all over his house, he wired in regular outlets and marked them as 12V solar to avoid confusing his house guests. He was able to find 12V LED bulbs with standard bases, so all he has to do is screw in these bulbs and plug the lamps into his solar outlets. He also installed a floodlight outside and ran all of the wiring through the floodlight box.

To soak up more sun for this or any other solar hack, try a 2-axis solar tracker.

Solar-Powered Mosquito Birth Control Is Making Waves

May 18, 2014 by Kristina Panos 81 Comments

Mosquitoes really suck. Joking aside, they spread dangerous and deadly diseases like Malaria, Dengue and West Nile. They like to breed in pools of stagnant water which can be difficult to keep up with. From egg-laying to larval development, still water is vital for breeding mosquitoes. Instructables user [Gallactronics] hypothesized that disrupting the surface tension of potential nurseries was the key to discouraging breeding, and he built a solar-powered device for under $10 that proves his theory.

There are a few standard ways of dealing with standing water. Someone can keep it drained or it can be sprayed with pesticides. By aerating the water, mosquito mothers are far less likely to successfully arrange their eggs on the surface. Even if the eggs take, the turbulent water surface will suffocate the larvae.

This bubbler ticks all the boxes. It starts as soon as it comes in contact with water and sounds a piezo alarm when the pool has dried or when someone removes it. It runs for 10 minutes at 10-minute intervals using a 555 timer and some transistors. The water probes are stainless steel bolts, and it runs on a 6V 450mA solar cell. Be sure to watch the demonstration below.

We love to see this kind of ingenuity and elegance in problem solving. Then again, we also like the idea of killing them with lasers.

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Boost Peak Power Tracking Battery Charger

May 5, 2014 by Brian Benchoff 25 Comments

[Rusdy] is building a solar charger for his electric bike, and quickly realized the lithium cells in his bike wouldn’t work well with the most common charge controllers out there. Solar cells have an IV curve, of course, and this changes with the amount of sunlight, requiring some conversion circuitry. Most of the charge controllers out there operate in buck mode, but the commercial boost mode converters [Rusdy] needed for his 36V battery are pricey as all get out. What was [Rusdy] to do? Build his own Boost MPPT solar charger, of course.

The circuit used for the charge circuit is fairly similar to a boost converter, with a little bit of logic required to get the maximum power out of the solar cells. [Rusdy] had an Arduino lying around, so that took care of the logic, and by sampling the voltage and current with the analog pins, he can turn a MOSFET on and off to get the most out of his solar cells.

The finished product works perfectly with an efficiency greater than 87%. Charging current and the final trickle charge is adjustable through software, allowing [Rusdy] to get the most out of his solar panels and electric bike. The board itself is just a prototype and could use a layout revision, but we’ve got to hand it to him for cloning a >$300 charge controller with an Arduino and a few scraps in a part drawer.

Low-cost Solar Panels Are Easy To Make And Reconfigure

April 1, 2014 by James Hobson 18 Comments

What’s the size of a deck of playing cards and can pump out enough power to charge your cellphone? These awesome little home-made magnetic solar panels!

[Christian Pedersen] has just published a guide on how to make these handy little solar panels, and they only cost about $1.25 each! They are capable of providing between 0 – 0.5V at 400-1000mA depending on the light available and load being driven.

All you need to make them is some multicrystalline solar cells, copper tape, Ethylene-Vinyl Acetate (EVA — a film used to protect solar panels) and Polycarbonate sheet for the external hard case. You can then assemble them in a matter of minutes, and laminate for a permanently sealed panel. He’s also added thin neodymium magnets so the panels stick together when you arrange them in a line! Perhaps a future version could have the copper strips going in both directions to allow for larger arrays to be made.

He also has a complete BOM on his GitHub, and if you happen to be at the Maker Faire in San Mateo in May, he’ll be showing you how — in person!

[via Instructables]

2-Axis Solar Tracker Always Gets A Tan

March 29, 2014 by James Hobson 21 Comments

Let’s face it — solar panels still aren’t that efficient. So why not pump as much juice out of them as possible? Building a 2-axis solar tracking unit can increase daily power output by around 30%!

[Jay Doscher] had his power go out back in 2011, and even though it was only for 12 hours, they realized how ill-prepared they were to deal with a power outage. Food was spoiled, flashlights were dead, candles were sparse… they needed to be prepared better for the next time this happened. This spawned one of [Jay’s] longest running projects on his blog Polyideas.

His goal was to build a fully automated solar tracking unit that could be setup anywhere, and automatically track the sun to ensure optimum ray catching. It makes use of a 12V gear reduced motor to provide panning, and a linear actuator with positional tracking to control the tilt. To track the sun he’s got a digital compass and an Adafruit Ultimate GPS breakout board. To control it all he’s using is an Arduino UNO, but he has been through multiple iterations including his first with a BeagleBone. It’s a very slick and well engineered system and [Jay’s] hoping to spread it around the world — the entire thing is open source. What a guy!

It’s not quite complete yet, but he’s got an amazing build log and a GitHub repository filled with info — plus the following video showing it off in its current state!

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