All of the parts for this tracker are from the trash, or soon to be trash, and were free... thus the "Trash Tracker" moniker.
I had wanted to try something like the redrok tracker for years but I didn't want to spend that much considering I would have had to buy the redrok plus the motors.
This setup is self powered and pretty simple.
The main parts:
4 solar panels from old yard lights. I got these lights out of a friends yard in North central New Mexico. I'm not sure what brand but I think they were Harbor Freight or something similar... cheaply made. They had sat outside in the dirt, snow, rain, etc. for a few years and I think only one worked when I got them. The plastic covering the actual solar panel had yellowed and deteriorated on all but one of the panels. I sanded them down with 320 grit wet/dry sandpaper then followed that with rubbing compound, polishing compound, then car wax.
Another yard light was used for the Return To East (RTE) function. Basically the light's PCB, batteries, and panel were used from this one. I once looked up part numbers I found on this light and some Malibu part numbers came up so I assume it's an old Malibu yard light. It uses two AA NiCd.
The drive motor is a worm gear affair from an old HP printer.
A normally closed micro switch from an old printer or scanner.
And finally an old 12" bike wheel from some kids bike that was tossed and left in my yard years ago.
I got the idea for this from this youtube video. Pretty darn simple and what I liked best was... in my case, I had all the parts and they were all free.
Board member Madscientist267 had put together a nice solar led light system here and mentioned wanting to add a tracker. I referred him to the same youtube video and decided I should get off my rear and 'pick up my hammer' and make one also.
Madscientist267 is working on his own version of a tracker and I expect he will be posting a story on his work soon.
Here's mine in it's cardboard mock up state.
Not shown in the photo is the limit switch screwed and taped to the bottom of the cardboard. A clamp similar to the ones holding the solar panels is clamped to the wheel rim to activate the switch.
Those are rubber bands running from the motor to the wheels axle serving as a tensioner for the motor's friction drive.
The solar panels have been soldered together in parallel then crossed wired, each set of panels has it's positive going to the other set's negative and visa versa. The crossed wires are then hooked to the motor's positive and negative.
Here's a schematic.
How it works:
Assuming both sets of panels put out the same amount of power... If both panels were aimed directly at the sun, the resulting power to the motor would be zero. Angling the panels allows for a differential voltage to be produced and will run the motor till the panels both are producing the same amount of power and once again zero each other out... stopping the motor.
It will track the sun in either direction although I haven't seen it do it yet. I does track a 100 watt light bulb and will do a complete circle in either direction without the RTE component installed.
The motor runs along the rim of the bike wheel which has had electrical tape applied for added traction.
For RTE I ran wires from the yard light's led to the motor with a diode placed to keep the batteries isolated from the tracker till it's dark. Once it's dark, the yard light turns on as usual but in addition to lighting it's led, it powers the tracker's motor back to the east for the next day's sun.
The micro switch is placed so that it interrupts the batteries power to the motor once the east facing position has been reached. Once the sun's up, the yard lights own wizardry shuts the power off to the led and motor till it's dark once again. The trip back during RTE is slow. To speed it up I will probably disconnect the led since it will stay on all night and drain the batteries and it's not really needed.
One problem I can see happening with this setup is a big dark thunderstorm causing the RTE to function and sending the tracker to it's 'morning position' then when the thunderstorm clears, the west tracking panel may be too far out of position to be able to track. I haven't tested this scenario yet.
The tracker will forward track with about a 3-4° precision. If for some reason it needs to back track, there's about a 25-35° 'null' zone. I have a feeling higher powered panels or a better motor could cut the 'null' zone down. If you watch the youtube video closely, you'll see his 'null' zone is small when it back tracks.
My original prototype used a small motor (unknown source) running along the bike wheel rim but it was under powered... lacking torque. Steve (Madscientist267) used a CD changer carousel for his tracker. I tried using a CD-ROM's eject motor and tray and it worked but as you can imagine, the range was limited. With my original setup, it wouldn't take too much wind to blow the setup out of track. With the current setup it's fairly stable and I hope to have it set up soon for use on my solar cooker.
The setup could easily be used to run a vertical axis.
Anyone have any ideas for a "throw away" source of suitable motors and turntables besides those already mentioned?
