I saw many DIY headlights using led technology. But they were not giving professional drive experience. Most of the bike users still use halogen etc. I tried to compile up a little guide for this.
I tried out for following major improvements :
1.As bright as an H4 bulb(1100 lumens)
2.traffic rules=a little(I shall not be responsible for any thing)
a.Anti glare light.
b.Beam pattern according to your driving side.
c. High /low beam.
3.Simple circuitry designs so that every one could understand them.
4.Not too costly
5.Shoult fit in your reflector.
High low beam can be obtained by using a powerful diode between low beam and high beam circuit in such a way than when voltage is applied to upper leds current passes and lights up lower ones also. Conversely when low beam is switched on diode reverse biases and upper ones don't light up.
Step 1: Parts Used
1w leds=20(Large viewing angle)
1.5 inch piece of 3/4inch metal water pipe.
Driving circuit(on next steps)
5volts Small fan
silver wrapping paper+cardboard. OR purchase antiglare cap from market
Wires: I got mine from telephone/intercom type wire. They contain enough copper to pass ampere or two easily(check for quality)
Reflector(I took an old one from my garage)
leds were 1w with an output between 60 to 80 lumens so 20 will be giving at least above 1000 lumens
Step 2: Preparing Led
2-3inch long wires which are striped are used to connect to both leads of led. Led connecting point having a hole in it is negative. Carefully choose the colors for negative and positive wires
Step 3: Heat Sink
cut out some aluminum sheet or angled one and adjust its one side to fit according to curvature of the pipe. Add good quantity of glue. Attach five fins like this. Cover the pipe with aluminum keep it smooth
Step 4: Attaching Led
now attach the led on the prepared pipe tightly. Hold them in position to give glue a setting time it is a time consuming step. Manage the wires by making clusters of five or six(depengs on driving circuit). In this you will have to deal with 8 wires. Making it easy to connect them in series or parallel. Increase the number of led on lower side and on right side(If car is driven on right side in your country)NOTE: you will not get a fine beam pattern as all of these led will not be on the focal point of reflector. You will get a wide beam angle so the range will not be too longer
Step 5: Cap
Cut away a piece of card wrap it around a bottle according to the size then glue it. In similar way cut a round piece. Use some shining type of wrapping paper to cover them.
Step 6: Hiding Wires
as too much wires will now be on upper side so here the cap will do the trick. It looks very beautiful from outside.
Now your led bulb is ready.
Step 7: Cooling
Attach a small fan on other side of pipe.12v or 5v(If supply is unregulated) with lm7805.
After this your light is complete
Step 8: 2nd Idea:Littles
What if you have got a pack of 8mm or 5 mm narrow beam led
Some people try to work with little's to get a big one, so did I.
Place them on some old compact disc to reflect back the leaking light and give a good appearance from outside
Step 9: Joining Led
Instead of soldering and wasting time. I rolled their legs onto aluminum wire as aluminum is malleable and ductile so they gat a good grip. Start weaving both legs on two wires. Then cut them in pieces of 20 or as you like. After this straighten them
Step 10: 3rd Idea:Lens+BIG Led
You can get a big led and attach two or three lens in front of them to converge it. It should at least be consuming somewhat 10 watts
Step 11: Circuit
semiconductor ic's die if reverse polarized so, use at least a protection diode in front of positive lead OR
You can use 1n5400 diode series to make a bridge rectifier if going to pass 2amp from them although their sheet says 4amps.use 2 in parallel or some 6ampere diodes if driving more led.
Step 12: 1st Way:resistor
If your bike/bicycle has got a regulated power supply than resistor method will be fine.
Using two 5w 1ohm resistors instead of one 2 ohm will give better heat dissipation hence longer life.
For calculating resistance following formula is used
e.g.=if 3.6 volts led with forward current of 180 milliamps is to be used on 12 volts than
R=12-3.6/0.180=46.6 ohm so 45ohm or 50 ohm will be fine.
NOTE; passage of current will increase along curved line(V-I graph) on increasing voltage.
Watts dissipated=voltage dropped*current passing
So, two 5w resistors instead of one will dissipate more heat.
in 5w resistor according to my opinion above 3w power should not be dissipated
Step 13: 2nd Way:Phone Charger
Get some phone charger open it to conserve space if your space is less. Similar to this will work
you can get 2.1 amps from it
These are switch based and have efficiency above 90%
Step 14: 3rd Way:linear Voltage Regulators
As a cheaper solution you can use linear voltage regulators.
If you have got some space to place cpu heat sink than well and good. Up to eight 7805 or two lm338 can be attached to it.
you can make your own as shown above. It was able to handle 0.5-0.6 amps through each ic
These are good if you are using some bicycle and voltage is between 7.5 to 15 your led will have same brightness.
although tantalum capacitors are needed but I used electrolyte and they worked fine.(Be careful about your case)
lm317 can be adjusted to 3.75 volts very easily by using 100 ohm resistors. Combine two resistors of 100 ohm to get 200 ohm. The ratio of 200 ohm(between adj and in) and 100 ohm(between adj and out)(three resistors in total) resistors will give 3.75 volts just very good. So you have prepared your own lm317---3.75 ;-)
Be careful R connecting adj and out should be at least 100 ohm because a very little current should pass through it and don't forget to use capacitors
Step 15: 4rth Way:Transistor and Mosfet
thanks to dan it can you can get all information here
As shown in second picture you can first connect transistor and mosfet so you will than need only to deal with 4 pins.
although the current is 0.5/R but you can use some high power variable resistor to get any value of current.
Step 16: Results
1st solution was good and I was driving easily although the beam pattern war broad. Visibility was above 150 feet approx.
2nd solution: according to opinion no even 80 led were not able to give good output their efficiency was low you can make them if you have got a pack and want to utilize but they will not be able to perform like powerful leds. Visibility= approx.100feet
3rd one is also good but will require some space between lens and source hence it might get longer(use two or three lens used in reading small writings) visibility=above 180 feet after adjustment
Any suggestions..... I like them. Try to vote if you can