Portable solar system with emergency capabilities for a sound system & amateur radio station.

Mobile Solar Sound System "Dares to go where no other sound system has been!"

Sound system is powered by sunlight with battery backup. High efficiency speakers are used and only 25 watts each is needed to reach volume levels of other speakers requiring 250 watts or more. There are two systems, one that will operate at 25 watts per channel at 12 volts dc and one that will operate at 40 watts per channel at 120 volts ac with included inverter. This sound system is great to bring to locations where no ac power is available.

Included in unit is a broadcast band fm transmitter with 1/4 mile range and two extendable antenna mast for amateur radio.

This system is currently being used outdoors for public service events as a PA system with ability to transmit wireless sound for remote video camera. The fm portion of this system is also used at the East Longmeadow  Rotary Summer Concert Series for handicap and those who want to listen in on their auto radio. Anyone that is hearing impaired could use an ordinary fm headset to set volume to desired level. September 11, 2008 this system was used by ELCAT (our town's local cable access station} to record the very moving remembrance service held at the East Longmeadow Fire Station. System was also used for National Night Out 2009. The most important use of this system would be for emergency situations where a communications or sound system is needed.

Last year East Longmeadow had its third annual national night out. Being one of the organizers and trying to make it better this year I realized a specialized need for a powerful portable sound system for some of our special demonstrations. We had our large Rotary Club Band Shell with its powerful sound system (8 Bose 802 speakers and 3000 watts of audio power) that worked just great for the coverage area intended. What was needed to cover the different events at different lactation was a self-contained, self powered sound system that could be moved easily.

 A friend donated 2 Altec Lansing speakers to me he purchased new in 1953. The speakers are huge about 3 feet high 2 feet wide and 20 inches deep, Not knowing anything about the speakers I said, they must take a lot of power to drive them. He told me just the opposite that 20 W of power would be sufficient and I thought he was exaggerating. I compared these speakers with 40 W per speaker to two Bose 802,s with 300 W per speaker. Used a inexpensive analog sound level meter at about 75 feet from each pair of speakers, and I got almost identical readings my ears told me the same thing. The speakers would fit the bill perfectly to make a powerful PA system they would be able to run off a battery or solar power. Only problem was the size and weight 60 to 70 pounds each.

I purchased a 40 x 48" utility trailer from a private party for $200. Bolted the speakers to the plywood and started building the sound system around the speakers. Mounted a folding shelf on one speaker that would hold a modular unit I built containing a Technics SA GX100 stereo receiver purchased for five dollars at Deerfield, a DI box, and FM transmitter. On top of the modular unit I securely mounted a Realistic 32 -- 1200 B mixer donated to me by another friend. The DI box ($35 new} was used to convert balanced microphone inputs to unbalanced line to match mixer input. The Ramsey FM 25 transmitter kit I built 10 years ago was to be the link to cameras and other remote FM receivers used for PA,s. On the back side of one speaker I mounted a power inverter that transforms 12 V into 120 VAC modified sine wave 400W 800W peak $34 new. Next to the inverter I mounted 12 volt dc 25W per channel audio amp purchased from Radio Shack 20 years ago in a clearance bin for $15. At the base of the two speakers a battery bracket was made to hold my RV battery a deep cycle group 24 standard battery approximately $70 to $85 new. On top of one of the speakers I mounted a flat round bracket with three-quarter inch pipe threads in middle. This threaded bracket is used to insert a three-quarter inch pipe threaded at both ends. The other end of the pipe has another round bracket threaded onto it. This bracket is used to mount a mag mount antenna for transmitting or receiving. Used a discarded citizens band magnetic mount antenna and cut it to make it into a quarter wave ground plane antenna for 88.7 MHZ. I have a Shure SM 58, wireless microphone that I use for our concerts. The receiver conveniently uses 12 to 18 V DC which made it very easy for me to connect with power poles to battery. Of course, it is very simple to plug-in a DVD player or MP3 player into mixer.

The unit was designed so it could be set up very quickly and moved about with a small tractor or by hand if necessary (a portable PA GO Pack] Most of the connectors are power poles and the modular unit has everything connected except speakers, power and antenna for FM transmitter. Set up can be accomplished in about 10 minutes or less. Have had no problem running system for six hours or more from battery, runtime could greatly be improve by use of a solar system .

This year's national night out, put the system to its test when the fire department along with the police department did a Jaws of Life demonstration. During this demonstration there was a very large area marked off with sawhorses cones and rope. There were many people gathered around this area two cameras were at opposite ends of demonstration. My sound system was set up at one corner of the crowd while the firemen narrating the procedure was about 100 feet from my unit and used my wireless microphone and speaker system so that the crowd could easily hear him above the noise of the diesel engines from the fire trucks and other equipment running. The camera that was at the far end of the event about 400 feet from my unit was receiving the audio from my FM transmitter through a $12 FM receiver. This was a simple setup, by all means, but everyone who has been watching the video on our cable channel has been impressed with the quality of the sound and the detailed narration by a firefighter. If the shotgun mics on the cameras were used to capture the sound all that would have been heard was the roar of the engines and the noise of the equipment.

I have used this unit for other events in town Lions Club, Rotary club, Fire Department, etc. I am very happy to help make events better in our town by providing a service that I have fun doing and can use my skills in electronics and amateur radio. If there were a genuine emergency this unit could be transformed into a portable transmitting station for amateur radio with the capabilities of a powerful PA system. It doesn't take a genius to put this type of unit together it is straight forward wiring a little imagination, and willingness to give of your time to others.

Al  KB1XG