Hi,
I have a 12V motor and I want to control it with a solar cell, when the sun shines the motor starts and when is cloudy the motor stops. I don’t know what I have to put between the motor and the solar cell to make it work.
The solar cell is giving me 1.3V in full sun and 0.3V when is cloudy. I was thinking at a relay but I don’t know where to find one to work in this range. I also think that should be something adjustable, the sun doesn’t shine always the same, depend on hour and season of the year.
Does anybody have any idea how to do it ?
Thanks

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How much current does your motor need? And can you measure the solar cell short circuit current under the two conditions? You can just connect a milliameter across it (assuming it is not a huge solar panel).
Don't get the idea that I think you might be able to drive the motor directly from the solar cell. We just need to know what the driver circuit has to work with, and what it has to do.

__________________
Ron

 

If my measurement is correct the solar cell current seems to be 0.02-0.03A in full sun. I do not know anything about the motor, nothing written on it except "DC 12V". I toke it from small inflating compressor powered from the car lighter.

 

That's only one condition. How much current in full shade?
You can measure the motor current with an ammeter by putting it in series with the motor and the battery. It would be best to measure it under the expected worst case mechanical load.

__________________
Ron

 

Some people use a tiny amplifire to boost the output of a small solar cell to drive a big load. It works with majic.

I don't know any shops that sell majic. A few shops sell amplifires but they exaggerate the spec's.

__________________
Uncle $crooge

 

EDIT:
My hair is standing up and I have goose-bumps.
MAJIC 102.7 from Miami Florida is on the web.
They are playing music from the '70s.
They have a fabulous amplifire.

__________________
Uncle $crooge

 

John, do you grow your own?

__________________
Ron

 

My daughter played at a gig the other year, one of the bands on was called 'The Amplifires' - they were a old band of fairly old people (compared to young teens anyway) - and weren't as good as my daughters band!

Mind you, they had a decent looking woman singer, a bit crinkly getting, but still pretty good!

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

I don't smoke anymore.
Of course I knew Mary Wanna. I was raised in Vancouver, B.C. which is (was?) the pot capital of the world.

I nearly missed meeting Mary because I moved from Vancouver to Toronto when the hippies in Toronto went to Vancouver. I haven't seen Mary for ages.

__________________
Uncle $crooge

 

Not sure that I would try to run a 12vdc tire inflator motor with a 1.3vdc .03a solar cell. If you pulled it off it would take quite some time before you could run it for a bit.

Maybe a smaller motor or bigger cell.

I live 35 minutes from Majic 102.7. I can receive it on my radio as well as the web here. Yes, I still have a radio (getting old I guess).

EDIT: Sorry, just re-read you are trying to turn it on with the solar cell.

 

I'll have a listen then! - I usually listen to WHTQ from Orlando that plays classic rock (more my era).

Up and running - Elvis playing!

__________________
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http://www.winpicprog.co.uk

 

I only want to use the solar cell as a switch, to start/stop the motor. Yes, I can use a smaller motor, 3V will be just fine.
Thanks

 

Do you have a power supply for the motor?, using the solar cell (or LDR) to switch a relay or transistor to switch the motor ON and OFF is easy enough.

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http://www.winpicprog.co.uk

 

Yes, there is a power supply for the motor. I was thinking to use a car battery, or for a 3V motor, 2 AA rechargeable. I am sure is not very complicate but I don't have a clue what kind of transistor and where to put it. I would like to have a schematic and some help.
Thanks

 

Look here http://www.uoguelph.ca/~antoon/gadgets/741/741.html

Figure 12 does what you want, use an LDR rather than a solar cell.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk