How To Make Very Cheap LED Bulbs At Home

LED bulbs are very popular now as it saves much energy than CFL bulbs.But LED bulbs are more expensive than CFL bulbs.But with a little knowledge on electronics anyone can make a LED bulb at home.This may cost about 5$.

Things you will need

#1.Sockets from a CFL bulb to protect all the electronics
#2.Electronic parts for the circuit (The details part numbers are given below of this post)
#3.50nos of 5mm LED bulbs
#4.Small piece of dot board or vero board
#5.A soldering iron and soldering wire
#6.Some wire
#7.A drill or a tool for drilling
#8.Some small screws (Optional)
#9.A hot gun or a very sticky glue
#10.2-3 hours of time

1st Step

Take your dot board and cut it into small stripes.About  1cm * 7cm.The dot board is recommended in here as it can properly hold the LEDs.But you can also use anything you want which can hold the LEDs when soldiered.
Here for the 50 LED bulb 7 stripes are used ,5 LEDs per stripe and 15 LEDs for the bottom).You can design your own too.

Now make holes at the corners of the stripes.You don't need to do this if you use a hot gun to attach the stripes to the CFL sockets.Finally smooth the edges of the stripes with a sandpaper.

2nd Step

Take your LEDs.Cut their terminals into same height,but don't cut it too much short.Now put the LEDs into the stripes,remember that they need to be put in series connection.(Positive to negative).

Now bend the terminals touching the opposite terminal of the next LED.

Then solder the connections.

When soldiering , use a soldiering iron of about 20W, higher temperatures may kill your LEDs.Use clean soldering iron.Do not hold the heat for the terminals for long times.

Finally all LEDs should be straight and solid in the stripes.Check all the LEDs with two batteries.

                                                          

Now take another piece of dot board about 6cm * 2.5 cm.It is the bottom part of the LED bulb.Insert 15 LEDs in series connection and do the same steps done in the stripes.Always check whether the LEDs are in series connection.After you soldier the LEDs you are ready to make the circuit.

4th Step

 

Here's the schematic of the power supply circuit of the LED bulb.You can download the PCB layout from the links below.

 Component side - http://dapalan.com/UbOI

Soldier side - http://dapalan.com/UbOq

 PS Viewer - http://download.cnet.com/Postscript-Viewer/3000-2094_4-10845650.html

Circuit Component List

 

#1.1nos 22R 1W resistor

#2.2nos 0.22uF 400v Polymer Capacitor

#3.1nos 1M 0.25W resistor

#4.Any metal oxide varistor matching 250V 5A regular use ( Change it matching your country's power supply)

#5.4nos 1N4007 diodes

#6.4.7uF 400v Electrolyc Capacitor(Use 10uF 400V if you can find one)

If your country's power supply is 110/120V all the capacitor voltages can be reduced to 250V.

Use the PCB if you know how to make it.Others can use a vero or a dot board for the circuit.

5th Step

LEDs are connected to the circuit in 25*2 rows.So take 5 LED stripes and soldier wires in series.

Soldier wires for the bottom part of the LED bulb (15 LED one) and take the socket from the CFL drill two holes(If there aren't)and put the wires through it and tight it.

Soldier the wires or the rest 2 LED sripes for the pottom part.

Now soldier the two rows of LEDs to the circuit.In the PCB there are no holes for 2 wires but you can put the wires together and soldier it.Always check for the polarity.

Now give it a test run.

All the LEDs should light brightly,if any of the LEDs doesn't work quickly turn off the power and check all the LEDs with 2 AA batteries and replace the blank one.Now you can move to the next step,attaching the LED stripes to the CFL sockets.

6th Step

You need a hot-gun or some screws with a drill for this step.Hot-gun or glue is easier but it will make your bulb irreparable.Attach at least one LED stripe with screws if you're using glue or hot-gun.

Take your bottom socket of the CFL bulb.Drill 7 holes at same distances and screw the LED stripes to the socket.

Remember we have installed the bottom part wires already to the socket.So no attachment to the bottom part is needed.Just tight up the wires of it.
Now take the upper part of the CFL socket and soldier the AC wires to it.You can use the remaining wires in it.No polarization is required.Use shrink wrap or some insulation to avoid short circuit at the soldier junctions.
After you complete the bottom take the upper part of the CFL sockets and mark holes by the attached LED stripes and drill them.Then again screw the LED stripes to the upper part of the CFL socket.

Congrats! Now you have completed making your own cheap LED bulb.

                              

To improve the light of the bulb

• Use 50mA LEDs (5050 SMD) instead of small 25mA ones.They are more energy efficient and bright.

• Use a 100uF 400v capacitor instead of 4.7uf 400V if you can find for absolute flicker free illumination.The capacitor may get bigger as the voltage.Always use capacitors matching your country's power supply.
• If you want to add more LEDs to the bulb increase the polymer capacitor value as follows. 

For 75 LEDs use 3 * 0.22uF capacitors or 0.47uF + 0.22uF.
For 100 LEDs use 1uF capacitor.
For 50 of 50mA LEDs (5050 SMD) use 1uF capacitor.

All the capacitors must match your country's power supply and polymer capacitors.LEDs are always connected rows of 25 in series,parallel each row.You can put your questions at the comments section.Check whether the LEDs are heating after 2-3 hours of illumination.If they are heating you need to reduce the capacitor value a bit to decrease the current.

The use of each part in the circuit

2*0.22uF Capacitors - These reduce the current to somewhere around 40mA which is safe to the LEDs.Increasing the value will increase the current.Use this calculator to get the reactance of capacitors.You can calculate the current by using V = IR formula.

22R 1W resistor - This resistor reduces the voltage to the circuit.You can add more LEDs to a series by reducing the value of this resistor.

1M 0.25W resistor - This resistor discharges the polymer capacitor in few seconds.Otherwise you'll get shock when you remove the bulb form the holder.

Metal Oxide Varistor - This protects your LEDs from lightning and high voltage spikes.Actually when using a varistor a fuse is connected to the live wire.But we didn't use it here as it is difficult to change the fuse of the bulb each time it blows.If your house's MCBs (Mini Circuit Breakers) are working fine,you don't have to worry.

1N4007 Diodes - These diodes rectify the AC current and convert it to DC voltage.

4.7uF 400V Electrolyc Capacitor - Even the AC current is converted to DC by diodes it is not smooth.This capacitor smooths the current and reduce the flicker.Use higher values to get better results,but remember to use the right voltage.