Total posts : 45366
Summer is almost half over, time to update my projec info
Basics: $10 Sosche (sp) FM transmitter and mp3 player intended to provide coverage for an apartment complex, pool, and dog park plus a small college next door.
I call the rig “Pool FM 90.9” I play electronic dance music, chill, and ambient because I could get as much as I needed free, no one else in town plays it, and it seems appropriate for the young apartment dwellers at the pool and the students at the college next door.
Transmitter modifications: 2 sets of 3 AAA batteries wired in parallel total 3.6 volts replace 2 aaa batteries giving 4 + days continuous operation. For the antenna, I have a quick disconnect from the negative battery spring to a solid copper wire about 16 guage I believe. The antenna stays in place and it has to support it’s own weight and stand up straight thats why I chose solid copper wire. I can quickly disconnect the transmitter from the antenna for battery changes and the antenna stays in it’s stealthy hideaway. The antenna with quick disconnect is about 29inches long. The other part of the antenna is an earphone extension cable about 2 feet long going between transmitter and mp3 player. The total length of this leg is approx 31 inches including mp3 player. If I am right this acts as a 1/2 wave dipole of sorts. The stealth location for my setup requires the wire antenna to be mounted verticle (good), and the earphone extenstion cable must run horizontal (not so good). This forms an L shape antenna. Thats all I did to the transmitter.
The mp3 player I modded with an adapter that turns 3 AAA batteries into a D cell. This delivers the 1.2 volts the mp3 player needs but ups the Mah considerably giving me about 4+ days continuous play.
The whole rig is in a super secret location overlooking the pool about 8 or 9 feet up.
Now the fun part, range.
I get what you would expect for a little transmitter. I can get a good strong signal out to about 400 ft before it quickly fades, but here is the fun part, that is on the FM receiver chip in a smart phone with earbuds as the antenna. 300+ feet to such a crappy reciever is pretty good in my book. I wish I had a better quality hand held radio to use to measure my range.
With a car stereo I blanket out to about 600 ft with a good loud signal, and a pretty good signal out to 1000ft in most directions and up to 1500 ft in a couple spots.
My apartment is 391 ft from the transmitter. I can pick up the transmitter with a good clear stereo signal inside my apartment and the corner of another building blocks the line of site from my apartment to the transmitter.
What’s inside my coverage area? The pool and dog park are within a 100 ft circle of the transmitter and so is the apartment complex mailboxes.
In the 250 ft circle, about 1/3 of the apartments and the associated parking lots are within this circle. Also within that circle is about half the parking lots for the college next door.
The 500 ft circle has 3/4 of my complex apartments, associated parking, and baketball and tennis courts. The 500 ft circle also includes the remainder of the college campus and about 1/4 of a larger complex above me.
1000 ft my entire complex, almost the entire larger complex, a pool for a third complex, 3 or 4 businesses, and a little portion of Interstate 40/75 that runs through Knoxville. This stretch of interstate carries a tremendous amount of traffic as it is a main east west route AND north south route.
So within my coverage area I have a goodly amount of people available to listen. Do they, I dunno. I have put a few fliers up around the complex to advertise my broadcast. That’s been the extent of my marketing effort.
The most expensive thing, batteries. It takes 9 AA batteries to power the entire rig, thats alot of eneloops.
I have another sosche transmitter, a belkin tunecast, a broadcast vision FM transmitter and a talking house AM transmitter to play with, I guess I got some sort of bug. The AM is my next project.
Thanks for reading my update.
I welcome any and all comments, suggestions, criticisims, praise, scolding, observations, or whatever you may want to ad to the conversation.