Dimmer for LED torch

Discussion in 'General Electronics Chat' started by Tdes, Mar 9, 2012.

  1. Tdes

    Thread Starter New Member

    Mar 9, 2012
    Hi All,

    I am new here (just registered) and know very little (almost nothing) about electronics, but i have a project on and seem to have opened a can of worms that has left me out of my depth!!

    I have a need for a LED torch that has good throw to the beam, so have been advised to use an xr-e r2 cree emitter. Where i fall down is that i want it to be dimmable via a remote lead.

    There are lots out there that are 3 mode, 5 mode etc, having varying preset brightnesses. What i would like to have is a dial that would take the brightness from 0% to 100%, with that dial being on the end of a remote wire (30cm long).

    I am thinking of using 2xAA batteries, i know an 18650 would give better performance but i hear horror stories about discharge rates, temperature and explosions, so think 2xAA may be safer.

    I thought that it would be just a matter of wiring an adjustable resistor inline, but i now know i was way off the mark!

    Any help, guidance, advice or tips would be much appreciated, but remember to keep it simple as i am a novice.

    Cheers, Tony
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
    An adjustable resistor will dim it but wastes power. I would probably use a 555 timer setup with adjustable PWM using a FET switching the power to the LED. The brightness is proportional to the pulse width and you don't waste power that way.
  3. Tdes

    Thread Starter New Member

    Mar 9, 2012
    Cheers for this info, It gives me a direction to go in.

    I think i am a bit out of my depth on initial searches of the circuits you have mentioned above!! Bit more research is needed.

    Can i ask where you would source the bits from? If i can find the three items as ready circuits that just need 'putting together' i may have a go myself or i may have to find someone to build one for me if it feels out of my capability.

    Many thanks for your help, it is much appreciated.