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#Post#: 1760--------------------------------------------------
solar led light
By: sut Date: March 13, 2014, 6:37 pm
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I was not sure where to put this but since it was about a cheep
solar light I thought it might go here ! Awhile ago I purchased
a cheep solar light (1 1/2 volt) 3 led spot light . Well it quit
working! (5 bucks does not buy you quality ) so I figured I
would investigate I found that the solar panel was no longer
charging the battery ! so I figured I would just use the led
lights to light something, But they wont light up when I hook
them directly to a 1 1/2 volt battery (Hmm ) so I thought the
lights were no good also !. I had a bright Idea and hooked them
up to a OLD 9v battery (6.12 v ) and much to my surprise they
lit up so how can this be ? this only had 1 1 1/2 v battery !I
looked at the circuit board and there is 2 parts on it 1. a
resistor 2. a JD1806 thingy it looks like a transistor but it
has 4 legs on it . So does that thingy boost the 1 1/2 volt
battery up to light the led
#Post#: 1761--------------------------------------------------
Re: solar led light
By: lynx wind Date: March 13, 2014, 7:10 pm
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You discovered the Joule Thief in the solar light. Its doing
the same thing our LJL does. It uses an inductor (thingy 1) and
the voltage is turned on and off through a transistor (thingy 2)
This gives rapid pulses of high voltage that the LED can
convert to light. The solar panel is usually a 3 volt panel to
charge the battery.
#Post#: 1762--------------------------------------------------
Re: solar led light
By: nessprojects Date: March 13, 2014, 9:02 pm
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Just to add to what lynx said above:- Led`s are very delicate
and it is the current through them that will blow them. Most
white led`s only operate at 3.4-3.6 volts of varying current.
5mm led`s work with about 20ma but 1W led`s work with 350ma
(both 3.4-3.6 V).
#Post#: 1766--------------------------------------------------
Re: solar led light
By: crazyguy Date: March 14, 2014, 7:24 am
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I hear even the electric cars use them to boost voltage to the
motors.
#Post#: 1767--------------------------------------------------
Re: solar led light
By: sut Date: March 14, 2014, 7:40 am
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I see !!! ok so since they use about 3.5 v I was really over
driving them with 6v but they are in a parallel circuit, so
does that make the 3 leds able to take up to 10v and could I
use my windmill to power them
#Post#: 1769--------------------------------------------------
Re: solar led light
By: crazyguy Date: March 14, 2014, 9:37 am
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I tried that.
You'll need to provide an over voltage protection or they will
burn out when the wind picks up, like mine did. The white LED's
turn yellow for about 2 seconds while they are burning out. ::)
#Post#: 1773--------------------------------------------------
Re: solar led light
By: nessprojects Date: March 14, 2014, 4:37 pm
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@ sut,
If the led`s lit on 6v using a dead battery then the led`s are
indeed connected in parallel (I assume there is 3) which means
you should only be feeding them with 3.5v but due to your
battery being nearly dead the current would have collapsed when
connected.
You can run led`s on almost any voltage but a resistor needs
connecting in series to limit the current, this method is very
crude but works on the smaller led`s but for higher power led`s
a simple driver circuit is much more efficient.
#Post#: 1774--------------------------------------------------
Re: solar led light
By: sut Date: March 14, 2014, 5:09 pm
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@ ness thx for that ! I hooked them up to my windmill which was
putting out about 3v/ 4v ac and they lit up good but they strobe
so much that I could never stand it . I did have the idea about
putting in a resistor to stop the over power but I didn't see
the need since I don't like strobe lights
#Post#: 1776--------------------------------------------------
Re: solar led light
By: crazyguy Date: March 14, 2014, 6:19 pm
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put a 470 uf capacitor across it. as long as you are feeding
them from a rectifier.
#Post#: 1780--------------------------------------------------
Re: solar led light
By: sut Date: March 15, 2014, 8:06 am
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@ CG Sounds like a plan and still need that resistor inline !
Now let me ask this can I take and tap into the the ac lines
out on the pole of windmill and and put in a rectifier to run
the led lights then continue to run the ac to the garage and
still use the same setup inside of my garage to charge my 12v
battery
I found this on instructables it tells me a lot
HTML http://www.instructables.com/id/Joule-Thief-Circuits-crude-to-modern/
I also looked up a simple driver circuit for led
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