10 October 2010

10W Retro-Futuristic LED Lamp

                          :10W Retro-Futuristic LED Lamp:

10W Retro-Futuristic LED Lamp


LEDs could be very efficient and  economical in long term use. A 10W LED lamp can replace a 100w incandescent lamp or a 30W compact fluorescent lamp. Despite an relatively high initial cost, compared with other kinds of domestic lamps, your electric bill could drop significantly if you use it instead.

Here I will show to you how to make your own stylish 10W Retro-Futuristic LED Lamp, spending around US$ 25 bucks. Let's go!  MAKING

                                            :Materials:

Materials

You will need:

1. One old burned compact fluorescent lamp, for the LED lamp socket  (anyone serves);

2. Two grip flat connectors;

3. One 10W LED: www.satisled.com/10w-high-power-led-white-600800lm_p134.html - color of your choice;

4. Two little screws (search in your tech scrap);

5. One 10W LED driver: www.satistronics.com/constant-current-power-supply-for-10-w-power-led-100240vac-input_p2174.html

6. Thermal paste;

7. One old computer cooler (search in your tech scrap);

8. Heat shrink tubing;

9. 30 cm of wire (2 mm). 

                                                :Tools:

Tools


You will need also:

1. Soldering iron;

2. Little screwdriver;

3. Small plier cutter;

4. Long nose plier;

5. Medium plier cutter;

6. Puncture tool;

7. Flat screwdriver;

8. Grip plier;

9. Little drill;

10. Electric drilling machine.

Your will need some oil drops too.

                :Disassembling the compact fluorescent lamp:

Disassembling the compact fluorescent lamp


Be careful to not break the CFC lamp. The glass could cut you and there are mercury inside the lamp.


Slowly try to open the base of the lamp, inserting the flat screwdriver and moving it up and down along the junction. These could damage the plastic a little, but it's not critical. You could after scrape the plastic with a knife or sand it to minimize the faults.


Carefully cut the two wires that join the circuit with the socket, without break the connection. Now cut about 0.5 cm of the insulation of the wire.

                     :Welding the LED driver to the socket:

Welding the LED driver to the socket
Welding the LED driver to the socket


Place two pieces of heat shrink tubing around the wires. It is important to isolate them and make a good finish.


Now solder the two wires to the AC wires of the LED driver and position and heat the heat shrink tubing for shrinking.

                                     :Cutting the base:

Cutting the base
Cutting the base
Cutting the base


Make a little V cut in the plastic base to pass the wires.

                                    :Boring the base:

Boring the base
Boring the base
Boring the base


Make two little aligned opposite holes with the soldering iron, and scrap them with a knife.
Now pass the 30 cm wire through them.

                                    :Bolting the LED:

Bolting the LED


Place the LED in the center of the cooler.


Mark the holes with a pencil-case and make a punctuation in them.


Drop a bit of oil and make the holes with the driller. Choose a drill a little smaller then the screws. They will make the screw when you tighten it in the soft metal of the cooler (cooper or aluminum).


Before you tighten them, apply some thermal paste below the LED.

                      :Connecting the grip flat connectors:

Connecting the grip flat connectors


Cut a little dent in the side of the connector of the LED, to not interfere with the sliding of the grip flat connector.


Make some adjustment in the grip connector with the plier, if necessary. They have to stay tightly connected in the LED contacts.

                                     :Linking the parts:

Linking the parts


Now, put the cooler above the driver and pass the wire inside the fins of the cooler.


Cut the wire leaving approximately 1 cm above the cooler.


Bend tightly the wire on the cooler, so that all stay firm.
                                     :Linking the LED:
Linking the LED


Grip the DC wires of the LED driver to the LED connectors. If one wire is short because the position, solder another piece on it.


The standard polarity is positive (red) to the LED contact with a little semicircle mark.


However, the chinese have poor standards and I have found some LEDs that have inverted polarity. Don't worry, if it does not turn on in three seconds, just switch the two wires that go to the LED contacts. The LED will not burn out.


Don't look directly to the LED! It's very, very bright and could damage your eyes. Be safe.

                                  :Finishing - the diffuser:

Finishing - the diffuser
Finishing - the diffuser


The LED alone is very bright and cast sharp shadows. You could make the light more smooth with a diffuser.


Cut the base of a 2L PET bottle and sand it grossly. Make four holes and put little hook wires in them. Now fit the diffuser below the LED lamp and voilá! You are the first in the block to have a 10W Retro-Futuristic LED Lamp!


Have fun and help to save the planet!





Supercapacitor USB Light

Supercapacitor USB Light:

Supercapacitor USB Light
                  :FEATURES:
For those who never heard about supercapacitor, you can check for more info about supercapacitor here. Supercapacitor is basically a capacitor with very high capacity, and the capacity rating is normally around few Farads. With the “super” capacity, it basically can store a lot of charge, and I am going to use the “super” capacity to store charges for a 5mm LED. Let’s see how long will the 5mm LED last.
 
 

Parts Needed:

Components Needed
The components you will need for this project is basically a supercapacitor (I am using 5.5V 0.1F supercapacitor which I bought from Farnell), a White LED, a 1K Ohm resistor and a USB male connector (I get this from an broken pendrive).
 
 

Supercapacitor Polarity:

Supercapacitor Polarity
Make sure you know the polarity of the supercapacitor, or refer to its datasheet
 

Soldering 1:

SolderingSoldering
 
                     :CLICK SEE LARGE PHOTOS:
 
first step is to cut the 2nd and 3rd pin of the USB male connector, we will need only the 1st and 4th pin (5V and 0V pin).

Then solder the negative pin of the supercapacitor to the 4th (0V) pin of the USB male connector.


Now, try to connect the positive pin of the supercapacitor to the 1st pin (5V). For the connection I am using a resistor leg.
 
 
 

Soldering 2:

SolderingSoldering
 
                     :CLICK SEE LARGE PHOTOs:

Next, connect the positive pin of the White LED to the 1st pin (5V) of the USB male connector.

Finally, connect a 1K resistor from the negative pin of White LED to the 4th pin (0V) of the USB male connector.
 
 
 

Circuit Diagram:

Schematic
Please check the diagram below for the complete schematic. You are actually free to use higher Farad supercapacitor, but voltage rating must be larger or equal to 5V, and you can have your creative way to connect all the components together.
 
 

Testing:

Testing
Now, plug it to your computer for around 10-30 seconds to charge up the supercapacitor.

You should see the White LED turned on (if it doesn’t turned on, there are some mistake in the connection), then after 10-30 second, you can unplug it and you should have around 10 minutes of the LED light.
 
 

Circuit Update 1:

Circuit Update
Circuit Update (6 Oct 2010)

I made some changes to the circuit, adding another resistor to limit the current consumption from USB port, and an ON/OFF switch to control the white LED.

The circuitry is simple, when you plug it into PC, the USB port will start charging the Supercapacitor, and there is a 10Ohm resistor (R1) limiting the current from USB port to 5V/10Ohm = 500mA maximum, but the R1 will also slow down the charging time. For large capacitance Supercap, you might need to let it charge for around 1 to 2 minutes. At the LED side, the S1 will let you turn ON or OFF the LED, and the 1KOhm resistor (R2) is to limit the current for the LED. If you use smaller value for R2, like 330Ohm, it will increase the brightness of LED but will also reduce the operating time of the LED for one charge. By using larger value for R2, you will increase the operating time, but reducing the brightness. I found 1K to be the balance value for the brightness and operating time.

Talking about the brightness and the operating time balance, I created another circuit that let you choose 3 level of brightness.
 

Circuit Update 2:

Circuit Update
In this circuit, the charging and USB port part is still the same, but I add in S2 and R3 at the LED side. So, the S1 and R2 will still function like the previous one, that by switching on S1, you will get the 1KOhm resistor brightness. By adding S2 and R3, it means that if you switch on S2, you will get 330Ohm brightness, which is brighter than 1KOhm brightness, because the resistor that limiting the LED current is now smaller and higher current on the LED means higher brightness. I say you will have 3 level brightness, so, the third level brightness is by switching ON S1 and S2 at the same time.
When S1 and S2 is being switch ON, the R2 and R3 form a parallel pattern, and you need some calculation to get the total resistance for the White LED.


The total resistance from the parallel of R2 and R3:

1/R = 1/R2 + 1/R3
R = 1 / ( 1/R2 +1/R3 )
R = 248.12Ohm
So, the total resistance at the White LED if you turn ON both S1 and S2 is 248.12Ohm which is 3rd level of brightness for the White LED.
- 1st level (S1 ON) – 1KOhm Brightness
- 2nd level (S2 ON) – 330Ohm Brightness
- 3rd level (S1 and S2 ON) – 248.12Ohm Brightness
 

 
 
 
 
 
 
 
 
 

07 October 2010

LIGHT EMITTING DIODE


                                                      LIGHT EMITTING DIODE (LED)
    A PN junction diode,which emits light when forward biased known as a light emitting diode(LED)
                                Fig.6.9 (a) and 6.9 (b) shows a symbol and construction respectively.


   It consists of N-type layer placed on a P-type substrate by a diffusion.Then a thin P-type layer is placed on the N-type layer.The metal connection to both the layer forms anode and cathode terminals.when light falls on the junction recombination of electrons with holes take place.After passing through the P-region the light is emitted through the window arranged at the top of the surface.
               When the LED is forward biased,electronics and holes move towards the junction and the recombination takes place.After recombination,the electrons,lyin in the conduction bands of N-region,fall into the holes lying in the valence band of
P-region.The difference of energy between the conduction band and valence band is radiated in the form of light energy.
            
The LED's radiate light in different colors such as red,green,yellow,blue,orange etc.some of the LED's emits infrared (i e invisible) light also.The color of the emitted light depends upon the type of the semiconductor used.Thus gallium arsenide emits infrared radiation gallium arsenide phosphide produces either red or yellow light,gallium phosphde emits red or green light and gallium nitride produces blue light.

ELECTROLUMINESCENCE IN LED:
                                                              In the PN junction of LED electrons are majority carriers in N-type material and holes are the majority carriers in P-type material.Electrons (in the N-type materials) exist in the conductionband and the hples (P-type materials) are in the valence band.
                                                               Therefore electrons in the conduction band have higher energy values than holes in a valence band when electrons move across a PN junction and recombine with a hole they release excess energy,the combining electrons release energy in the form of heat and light.LED's are constructed in a such a way that PN junction is contained within a translucents material and a large exposed surface area on one layer of semiconductor material permits the photons to be emitted as visible light.This process is called electro luminescence.
                                                        The light that result from the conduction of these PN function is reason for the name light-emitting diode( LED )

SEMICONDUCTOR MATERIALS USED FOR LED:
                                                                           LED's are made from doped gallium.Various impurities are added during the doping process to establish the wavelength of the emitted light remember that wavelenght determines the color of the light A Gallium arsenide (GaAs) will have a green glow or infrared. Gallium arsenide sulphide (GaAsS) glows red.gallium phosphide (GaP) glows yellow and gallium nitride (GaN) glows blue.

    Applications:

                      LED's are used to:
(1)   Displays are used to indicate alphanumeric characters and symbols in various system such as digital clocks microeave ovens stereo tuners calculators etc.

(2)  Indicating power ON/OFF conditions.

(3)  In optical switching applications.

(4)  Are also to send light energy to fiber optical cable,which transmits energy by means of total internal reflection.

(5)  For image sensing circuits in picture phones.