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Step 2The new turbo circuit.
The new circuit uses fewer parts than the original but can deliver over 80mA, almost 4-times the current to a White or Blue LED while using about 250mA, which is double the efficiency of the original design.
We will need to use 1/2W LED, which are readily available on eBay:
here, or here. They each have slightly different products, but I've used both and they're both reliable.
The real star of this circuit is the driver transistor, FJN965, from Fairchild Semi. Capable of handling up to 5-amps of current in a TO-92 case, it will start at .9v and run the light until the battery drops to under 0.3-volts. You can get them from http://fairchildsemi.com
Resistors, capacitors and inductors can be obtained from your local supply houses (eg Radio Shack, The Source), Sure Electronics, or at online surplus stores, like http://AllElectronics.com
The second image shows the layout using a Perfboard. S+ and S- indicate the wires from the Solar cell.
We will need to use 1/2W LED, which are readily available on eBay:
here, or here. They each have slightly different products, but I've used both and they're both reliable.
The real star of this circuit is the driver transistor, FJN965, from Fairchild Semi. Capable of handling up to 5-amps of current in a TO-92 case, it will start at .9v and run the light until the battery drops to under 0.3-volts. You can get them from http://fairchildsemi.com
Resistors, capacitors and inductors can be obtained from your local supply houses (eg Radio Shack, The Source), Sure Electronics, or at online surplus stores, like http://AllElectronics.com
The second image shows the layout using a Perfboard. S+ and S- indicate the wires from the Solar cell.
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I would like to first thank the original poster for this circuit.
I have been trying to build one of these myself using this schematic as a guide. Unfortunately, I cannot get an FJN965, and so I have used the NTE11 which is apparently an equivalent component( I think the pin out may be different though). I have used a discrete inductor as well as a wound one that I have made, and I am still having trouble with getting the voltage to boost to 3.3 V , though it does turn on and off depending on whether sun is out or not ( turns on when I cover with my hand and turns off when I let the light hit my solar panel ). My battery voltage is mimiced at the LED.
If you have a 6v supply already, then you will not need to 'up-vert' the voltage at all. Just connect the LEDs through a suitable resistor and add a light-sensing switch for day/night operation.
Hope this helps - let me know your exact application (# LEDs, etc) and I can provide more help in assembling your light.
If you have 15-ft (5m) if a thin insulated wire, you can make your own - just wind the wire around the barrel of a felt marker (anything 1/2", 12mm in diameter will work). You don't need to be neat, just jumble wind into a donut shape and tie or tape together after removing from the form. This will give you a 22uH air-core inductor, and will be able to handle up to 1-A of current.
You can also get an assortment quite cheaply here on eBay.
And with thise parts you want to assemble a single light with 4 LEDs. is that right?
Then the simple solution is to take 3 batteries, and charge them with 3 solar cells with a diode in between - like the picture below.
My suggestion is to charge the lights up first and see how well they serve your lighting needs. If mains power is avilable, it may be a better solution to build a LED "bulb" like this one here, which has the brightness of a 25-40watt bulb but only uses 3 watts for under $10.
If you bought the 10mm LEDs from RS, then be warned - they are not "brighter" they just have the beam more focused - so it forms a very tiny spot of light, so they may not suit your needs.