Sunday, July 24, 2016

DIY LED Torch

If you go out to visit someplace or go on camping a torch will be very handy right? You can use a mobile phone flash for the job but it will be much more comfortable to use an actual torch and it will be more fun if you can make one for yourself right? This post is about making your own LED torch.


Components needed:

1. Integrated circuit: MAX660.
2. Capacitor: 1*22uF and 1*100uF, better to get tantalum type capacitor.
3. Diode: 3*1N4148, LED: 3*High brightness LED.
4. For power use 2*AA Cells.
5. Enclosure for circuit, battery and reflector for LED.
6. Don't forget to put a switch between source and circuit that will serve the purpose of turning on/off.


Circuit Diagram:



 How it works? 

The first question that you might ask is why do we need an Integrated circuit for this! LED can be used directly with a power source, maybe limiting the current via a resistor will be enough and yes you are correct but in this arrangement of constant current provided by the MAX660 integrated circuit that is in voltage Inverter mode will be able to drive them at constant brightness.

So simply we are powering the LED via two AA cells, typically 1.5V per cell for non rechargeable one. You can use rechargeable cells too but probably disposable Alkaline cells will be better suited for this purpose. You might want to read why is that!

Like I mentioned above MAX660 will provide a constant current which in this case is 100mA is enough to drive multiple LED which is done in this circuit.

I forgot to add a switch to this circuit, you can just add it between Bat+ and Pin 8 of the integrated circuit.


Resource:

1. MAX660 Datasheet
2. LED Driven in constant Current
3. My other posts.

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