dark activated led light controller board.

Hi.
recently my solar chargeable led light fixture stopped to work.It won't turn on.It has 3 high brightness led straw hat types,and runs on 2 of 1.2v rechargeable batteries.
A LDR turns in on while in dark.The PCB has a COB type ic. Which can not be identified.The other problem is this circuit run on 2.4v only.
I googled for such controller,I only get results for 6V,9V, or 12V circuits with a relay.For low voltages not anything below 3 volts.
The original board worked like it will turn the lights completely on or off,but all the circuits for 3v tried are working by increasing gradually the voltage for leds,So in low light the led are turn on dim,with the dark increasing they come to full intensity and vice versa.Not good.I need the circuit to turn them on and off at certain dark and light levels.

Can any one please help me for what i need?

Most white LEDs work above 3.3V. There may be a voltage doubler inside. Check voltage on LED. This converter then, is controlled by LDR.

Thats right most white LEDs work on 3.3v.i took a look at the board again.Since the chip is COB,its attached to the board vertically and has five pins i believe.i dont have it with me right now..I was able to find a miniature markings on the COB,it says JD1081. Since there is an inductor on board means it could be a voltage doubler.
Tomorrow i will try to reverse engineer the schematics and post it here,its a tiny board with few resistor and an inductor along with COB.It will be easy task to redraw it.

waiting your reply then....

Hi, Sorry for being late.It was a busy day.
Yet i managed to draw the schematics. Its attached here.



Here is the image of the board.


I tried to find the manufacturer for this chip and came up with this Chinese company.
**broken link removed**
the difference b/w two chips is number of pins mine one has 5-pins the other one on the company's page has 6-pins.No details are available but English version of web page says it related to solar applications.
Thank you.

Did you check,if your LDRht is OK. Test its resistance with multimeter in light and dark. In light it should be lower than 1k and in darkness it will be above 1M. Try to feed input of IC with voltage signal to see if IC is partially damaged If boost converter is working and LED turns on. In this case only a control circuit is required, otherwise a new circuit using discrete components is easy to develop.

Hi, ALERTLINKS.
I tested the LDR. ITS good no problem with it.Voltage feed to ic makes no difference it won't work.The chip is certainly dead. So total redesign is needed. Any hints to start with.What kind of voltage doubler is suitable?

Have a look on these driver circuits.
http://elm-chan.org/works/led1/report_e.html
http://elm-chan.org/works/led2/report.html
Light activation circuit can be added to it.

Hi,ALERTLINKS.
Just finished and tested the circuit in 2nd link.Worked like a breeze.Transistors and diode a different but close to parameters of originals,can arrange originals later.Right now its working.
A wonder full thing.The feature i like the most is feed back of output current and its regulation is nice.Thanks to you for the links and many thanks to maker for his creation.

Now the second part light activation through LDR in the dark.
Can you help me out again.
Thank you very much.

I drew and simulated in proteus.

Hi,ALERTLINKS.

The LDR controller worked just like i wanted it.I respect you brother.
Much obliged.

I am not from Lahore. I am from Bahawalpur.So i happen to visit Lahore once or twice a year.Can you suggest some books for electronics available at lahore.Those for basic level like transistor circuits,well elaborated,easy to understand.

You don't need to buy local books while there are thousands of free resources available on net. You can download in Urdu as well.
For example.
http://www.electronics-tutorials.ws/
http://101science.com/Radio.htm
http://www.freebookcentre.net/Electronics/Analog-Electronics-Books.html


As you are a rapid builder, learning in a practical way is easy and more fun by building projects. Download these pdf documents and build what you like.
http://www.talkingelectronics.com/projects/200TrCcts/1-100TransistorCircuits.pdf
http://www.talkingelectronics.com/projects/200TrCcts/101-200TransistorCircuits.pdf
http://www.talkingelectronics.com/projects/50 - 555 Circuits/50-555Circuits.pdf