Cheapest High power LED driver circuit schematic

There are many other articles on internet with simpler circuits but none of them are cost effective or as cheap as this one.
Using some easy to get cheap components you can make a much better LED driver than you would have thought of.




In market, we can get 1Watt and  3Watt LED easily. And the ratings of those 1Watt LEds are  Forward Voltage 3.2V – 3.6V, Forward Current 300mA and for the 3Watt ones,m the ratings are Forward Voltage: VF3.4V , Forward Current :700mA .

So we consider 3.4volts as optimal voltage, and thus the 1watt LED is giving 3.4×0.3=1.02Watt and for 3watt it is, 2.38Watts.

So here’s the simplest circuit that can be used.

Here, for a fixed reference supply, LM7805 regulator I.C which can deliver upto 1Amps of current, and in our cases the max required current is 700ma or 0.7Amps, so no problem there. And since the resistor “R” will be eating the extra 1.6 volts(5.0-3.4). So what would be the value of R?

For 1 watt model, there’s current of 300mA, so the value of the resistor should be 5.3 Ohms(appx) and wattage should be 0.48. So a 5.6ohms 1/2watt general purpose resistor will do the job perfectly. And similarly, for the 3Watt model, the value of R would be 2.2Ohm 1.25Watt(or 2Watt).

We can feed any voltage greater than 5.5 volts, so we can run this circuit in 6Volts supply or in 12 volts supply.