How to build a complete solar and wind powered mobile disco/mini rave sound system to entertain your family and friends!
As a fun project I have built a solar and wind powered sound system, which I take out and about to camping expeditions and the like.
It's built from a 12V car amplifier and a bunch of recycled studio monitor speakers. The wind turbine can generate up to 300W of power and the solar panel up to 130W of power. I also have a pedal generator which can be used with a mountain bike and an enthusiastic human to take it up to 11 when required.
I use around 650Ah of deep cycle battery capacity, which will run the amplifier and also some LED disco and ultraviolet lights, to add a bit of atmosphere.
A laptop computer provides the tunes! The sound quality is crystal clear as there's no generator noise to overcome.
Ingredients (use recycled wherever possible!)
1 x 400W car amplifier (e.g. from Maplin)
1 x piece of plywood to attach the amplifier to 1 x 130W solar PV panel (e.g. Kyocera)
1 length of solar cable to connect the panel to the charge controller, cut into two lengths for positive and negative
1 x 30A solar charge controller
2 x 125Ah deep cycle (leisure) batteries
1 x 150Ah deep cycle (leisure) battery Lengths of positive and negative battery cable, with the correct ends for your battery terminals
2 x battery-to-battery connector cables (for the two 125Ah batteries)
1 x LED disco scanner light with built-in mike input
1 x LED ultraviolet cannon panel (e.g. www.uvgear.co.uk/product/product211.htm)
1 x FM transmitter (e.g. from Mobile Black Box)
1 x laptop computer (to play the music!)
1 x cable - 1/8" headphone jack to 2 x phono jacks. You will probably also need two leads to turn
1 x phono jack into 2 x phono jack, as the amp will probably have 4 phono inputs
1 x 300W portable wind turbine (e.g. from Navitron)
2 x cables to run the positive and negative from the wind turbine to the batteries 4 x 8Ohm bass speakers (able to handle 100W each)
4 x 8Ohm midrange/treble speakers (or old studio monitors) (able to handle 100W each)
1 x 300W 240V A/C inverter (e.g. from Maplin)
1 x 4- or 6-way plug extension lead
1 x strong, waterproof gazebo to set it up in out of the rain (!)
1 x compass to align your PV panel optimally Cable ties
There are two sections to the system:
* the mains equipment (laptop and lights) which are powered from the 150Ah battery through the inverter
* the low voltage equipment (amplifier) powered from the 125Ah batteries, recharged by the PV panel and wind turbine
STEP 1: Screw the amplifier down onto a piece of plywood to keep it secure. Screw the solar charge controller onto the same piece of plywood and connect the amplifier + and - to the 'load' + and - connections on the solar charge controller. A switch should be connected between the + terminal on the amplifier and its 'on/off switch' terminal. Wire two bass speakers together on each side of the gazebo, and then wire one on each side to the bass side of the amp. Do the same with the midrange/treble. Your amp should have built-in crossovers so that you can adjust the crossover frequency to get the best sound out of your speakers.
STEP 2: Connect two cables into the + and - battery terminals of the solar charge controller, and the other ends onto one of your 125Ah batteries. The second 125Ah battery should be connected to the first, + to + and - to -.
STEP 3: Prop the PV panel up on the south-facing side of your gazebo, leaning against one leg. Secure it with cable ties so that it doesn't move. Connect the PV panel to the solar charge controller. Your PV panel should now be charging your batteries.
STEP 4: Set up your portable wind turbine. If you use the Navitron one, it has a built-in charge controller so you don't need to buy one. Connect the + and - leads for the wind turbine onto the second 125Ah battery. Your wind turbine should now also be charging your batteries.
STEP 5: Attach the crocodile clips for your inverter to the 150Ah battery, which you should make sure is fully charged before you begin. The 150Ah battery is not charged by anything, but should be big enough to run your laptop and your LED disco lights for days on end before it needs recharging. The solar and wind only charge the batteries which are running the amplifier.
STEP 6: Plug your laptop and LED disco lights into the plug extension lead, and plug that into the inverter. Set up your lights where you want them, and your laptop on a table. Your laptop should be full of mp3s of all your albums. Plug the laptop headphone socket into the power amp with the correct cabling. Plug the FM transmitter into the same lead which is going to the amplifier; you will need a splitter cable which may come with the transmitter.
STEP 7: Pump up the volume!!!
Your system should run for days on end on only wind and solar power. If weather conditions are poor for the system, turning it down helps the batteries to last longer. Even if the volume is low, the system is transmitting your music locally on a stereo FM frequency of your choice, so people with FM radios will be able to pick up the music and listen to it on personal FM radio headphones 'silent rave' style!
Care should be taken with the batteries since accidental shorting will result in the release of a large amount of energy with the potential to cause injury or fire. The risk of accidental shorting can be reduced with the use of insulating terminal caps.
Electricity can be dangerous! If you are unsure of your ability to carry out this project safely, please do not attempt it. Although the BGI makes every attempt to ensure the accuracy and legality of all newsletter content, it cannot be held responsible for any harm or financial loss resulting from acting upon it.
photos (c) Solar Bud 2009
Andy Hunt writes the Green Cottage Blog where you find all sorts of DIY green projects for house, garden and beyond.
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