Fotocell? Photocell? Light sensitive sensor....

Post Reply
Prepper
Posts: 5
Joined: Fri Nov 30, 2012 2:39 pm

Fotocell? Photocell? Light sensitive sensor....

Post by Prepper » Mon Dec 17, 2012 10:52 am

Hey.

Starting another project. I have a led light string, it's power by four AAA battery's. I want to build a light sensitive circuit. So it will turn light on when it gets dark and turn light of when the sun comes up.

Plz help

Solar98632
Posts: 246
Joined: Tue Jan 15, 2013 3:10 pm

Re: Fotocell? Photocell? Light sensitive sensor....

Post by Solar98632 » Sat Jan 19, 2013 3:20 am

a photo resistor would be your best bet, hmm..if you still have those solar lights they should have one. Unless it is using the light from the cells to deactivate the circuit. Photo resistors are cheap

Solar98632
Posts: 246
Joined: Tue Jan 15, 2013 3:10 pm

Re: Fotocell? Photocell? Light sensitive sensor....

Post by Solar98632 » Sat Jan 19, 2013 3:23 am

this is what the circuit would look like
Attachments
ldr.JPG
ldr.JPG (17.09 KiB) Viewed 14295 times

techman
Site Admin
Posts: 1323
Joined: Thu Dec 22, 2011 11:49 am

Re: Fotocell? Photocell? Light sensitive sensor....

Post by techman » Tue Jan 22, 2013 8:50 am

What about using the circuit from the path lights for this project? The circuit already shuts off the circuit when the sun is shining. When light hits the solar cell, the transistor turns off the LED. When there is no light, but transistor turns on the LED. You could use the circuit to turn on a higher power transistor, which turns on the LED circuit.

But the circuit you show should also work fine. It depends on where the light sensor is. On the bottom of the circuit, from base to ground works one way. On the top, as shown, from base to positive, it works the other way.

Solar98632
Posts: 246
Joined: Tue Jan 15, 2013 3:10 pm

Re: Fotocell? Photocell? Light sensitive sensor....

Post by Solar98632 » Wed Jan 23, 2013 6:44 pm

Hmm you can also Use techman's idea and go one step further, You can re-charge a battery and have your unit be self reliant.
You can use the solar panels to re-cahrge you lights.

Solar98632
Posts: 246
Joined: Tue Jan 15, 2013 3:10 pm

Re: Fotocell? Photocell? Light sensitive sensor....

Post by Solar98632 » Fri May 09, 2014 6:58 pm

I completely forgot about this ..I got pretty busy with my son.. will get back to this project ...an great ideas.. and I think I might adapt this circuit for th le Mr Beams. .when I am not busy chasing Patrick...all my electronics .. got tossed...literally ... so I am having to restock as well.

Solar98632
Posts: 246
Joined: Tue Jan 15, 2013 3:10 pm

Re: Fotocell? Photocell? Light sensitive sensor....

Post by Solar98632 » Mon May 26, 2014 10:45 am

Yeah, the path way lights is a much better project. Found something out about the LEDs they shut them selves off when you pair to many.

techman
Site Admin
Posts: 1323
Joined: Thu Dec 22, 2011 11:49 am

Re: Fotocell? Photocell? Light sensitive sensor....

Post by techman » Wed Jun 04, 2014 9:48 am

It may be that when you connect too many LEDs on the circuit that they are trying to draw too much current. The circuit just cannot handle all the draw. You may have to use a transistor on the output to allow you to connect more LEDs to the circuit.

I know you have been concentrating mostly on your home off grid solar setup. It would be a lot better if you bring all of your questions and comments about your solar panel setup over here to the forum. This is better and easier for me to follow than through all the comments scattered through a bunch of videos.

Plus I would love to see some photos of your setup so far. Please keep us updated here on the forum.

Post Reply