It's great to make power from renewable sources, it 's equally important to find the best ways to use this treasured power. I believe low powered Led's are one of the
most reasonable in terms of cost resources for a 12 volt battery system. The latest 10mm diameter high brightness white led's offer great potential.
The 10mm LED diffusing experiment.
Whilst Led's are a great energy efficient substitute for incandescent lamps, they do suffer from a having a rather directional beam of light, sometimes as low as 20 degrees.
I bought fifty 10,000 Mcd white 10mm led's off eBay to experiment with. The led's were powered from a 9v pp3 battery with 390 ohm resistor on each.
They were the 30 degree viewing angle type. Rated current per led was 25 ma, I think they run a lot longer at 15ma each, with no real loss in intensity.
Full L.E.D specifications can be viewed here
I wanted to diffuse the directional light, so the led provided a better 'volume' of light, for use illuminating a garden shed.
I thought Filing the led's dome flat would work, but that only had a small effect in diffusing. A better, more successful solution was to 'frost' the plastic casing simply
by sand papering with a light grit paper using a small circular motion. This gave me nearly 180 degree dispersal of light.
Update: I have recently found a product that makes life a lot easier, if a large quantity of led's need 'frosting', Plastikotes glass frosting spray is ideal.
product info here
The1.2 Watt LED Cluster Lamp
This was an exciting project, producing a good volume of light for little over 1 Watt of power, 1 Watt !
I soldered nine 10mm white led's on a printed circuit board, 3 led's in series strings and then connected 3 in parallel, six 45 ohm resistors were used. I also left about 5mm clearance above the circuit board to allow for additional led angling and light spread.
This worked very well, I ran this cluster light from a 12v battery and it drew a tiny 100Ma of current, that is a mere 1.2 Watts of power. The light was adequate
to locate tools in my shed, with a good volume of light. Two or more modules could be connected up to give more light if required.
This module could also be used in 12v cars or trucks as a low power, high brightness lighting solution.
It is thought that the compact fluorescent lamps are the most efficient, they probably are, but not by far in my opinion, they also cost a lot (£20)
for a 12v version and start at a minimum of 7 watts. This cluster lamp was made for £2.50.
If you want to power strings of LED's here is a good page of circuit diagrams.
Kindly supplied by Glenn Hurd
The PP3 9V Battery Clip Torch (for 76p)
Every year when you change smoke alarm batteries, you end up with a handful of 9 volt batteries that are essentially ok, just a little discharged.
If you don't have any other
devices that use them, then they often just end up in the bin.
This LED idea clips onto a 9 volt battery and turns it into a great pocket emergency torch, that will run for a good few hours as it only draws 20ma current.
Readily available components and simple soldering required - can be made in 1 hour.
A small switch could be fitted, but there is no real need - just clip connector on or off for illumination.
Using one led is a bit wasteful, given that we have 9 volts, you could use two 5mm white leds in series with a 180 ohm resistor, but space gets very limited,
and the volume of light is not that different to one 10mm L.E.D.
Rigid PP3 Battery clip (Maplin code NE19V) 39p
10mm White 11000mcd LED (eBay) 24p
390 ohm resistor (0.6w) (Maplin code M390R) 13p
Note: Ensure the polarity is correct and insulate LED wires from each other. Don't stare directly into LED.