Photo Sensors and a tracking device

[Derek]

I've been looking at creating an inexpensive tracking device that will rotate my solar cooker on a bearing platform throughout the day to focus it at the sun the most.  My thoughts are have a sensor on the west side of the unit, and when sunlight strikes it, it will have power flow through it for a split second which will kick on a small motor turning the unit until the photo sensor is shaded again.  And then there would be another one on the east side of the unit that would catch the next day's morning sun, rotating it either another 180 degrees around, or back the other way preferrably to face the sun again.  This one would turn the motor until it was shaded of course, and then the process would start over.

Here are the photo sensors I was looking at:

http://www.bgmicro.com/prodinfo.asp?sid=026460648148148121617674221&prodid=RES1402&page=1&am



p;cri=photo&stype=3

http://www.bgmicro.com/prodinfo.asp?sid=026460648148148121617674221&prodid=RES1412&page=1&am



p;cri=photo&stype=3

And here are just a couple of motors I was looking at:

http://www.bgmicro.com/prodinfo.asp?sid=026666666666666721617674221&prodid=MOT1039&page=1&am



p;cri=MOT&stype=2

http://www.bgmicro.com/prodinfo.asp?sid=026858796296296321617674221&prodid=MOT1032&page=1&am



p;cri=MOT&stype=2

http://www.bgmicro.com/prodinfo.asp?sid=026746527777777821617674221&prodid=MOT1045&page=2&am



p;cri=MOT&stype=2

So I'm looking for feedback on this.  Obviously, this could be a rather inexpensive way of getting solar panels to track the sun as well.  But mostly, this solar oven is going to sit in a big window, so wind isnt a factor here.  What are your thoughts?

[adelaide]

hi i been using a basic home made 1 like that i used 1 sensor( more epensive 1s swich higher currents) to triger lo current relay in car cent locking control box .

it moves a old cordless drill on some thred with bolt welded on tube as a hydrolic type movment. i use the soler cells them self for return (positive side goes neg at end day if diod up line) , and few limmeting swiches   cheeep and good most days when sun out

[ghurd]

You have seen the redrok dot com site?

The CDS cells are suprisingly sensitive and show repeatable consistency. We used to use some homebrew CDS cell based LED output testers.

Not sure how or why the unit would gain anything using stepper motors (and their related hardware).

I would guess the gear head motor would be cheaper and easier.

G-

[The Crazy Noob]

Not a lot of people know this, but you can use a LED as a light sensor. It wil create a (small) voltage that is equal to the amout of light that hits the LED.

[georgeodjungle]

i use the redrok ones on one of my cookers.

with old satellite actuators.

like mr ronco said "set it & forget it."

[Nando]

Derek:

There is a better way of doing tracking, go to redrock.com the site sells a very good solar tracker.

I am quite familiar with photocells since the early 1960s and for a good tracker one needs to have a delta circuit for proper direction and position correction.

redrock.com has such device and it is simple, saving you at least 100 hours of work.

Nando

[Walt]

Nando

The web address should be redrok.com, it took me a while to find it. Thanks for info.

Walt

[bob g]

about 30 years ago i set out to build a solar tracker such as described

i used common photo resistors, and relays to control linear actuators,

using the photoresistors mounted in black tubes

i set one in a 12 inch tube, that was used as a cutout when the tube was directed at the sun.

i used 4 more mounted around the center tube, but in shorter tubes, for up, down, right and left. these activated the relays controlling the actuators,

to that i place 4 more inbetween the 4 to make corrections for the arc of the sun.

in a dark room the thing would track a flash light moving moderately slow, but much faster than the sun moves.

i never got to the point of building the parabolic mirror, but am convinced it would track the sun quite well, the outer actuator tube length would have to be tailored so the tracker could realign from sundown back to the sunrise position without human intervention.

bob g

[Volvo farmer]

But, if I built my own, I could only spend $10 in parts and save the $35 expense. In 100 hrs, I could save myself $.25/hr.

Just kidding, of course. This redrok thing is so slick. It parks in the east after sunset and everything. When I saw the circuit boards I bought from Duane for $35 ea and thought about how much time It would take me to develop, engineer, buy parts and solder the thing together, the choice was obvious.

Some things are worth fiddling with for the education and cost savings involved. Nando is much smarter than I am in electronics and he is recommending these trackers.

Grasshopper, as quickly as you can, snatch the ready-built tracker from Duane's hand.

[Norm]

  Use a gear drive motor ...like an electric window motor...

a small cassette

player With Automatic Reverse take the tape

and shorten it so it only has a playing time

of 5 minutes put some foil tape half way so it

will switch on the gear drive motor for about

3 or 4 seconds....now it will move in small

increments every 5 minutes...and you don't even

have to be really brilliant in electronics ....

like I'm not.

          Real Fun !

                      ( :>) Norm.