design one led torch

Discussion in 'General Electronics Chat' started by athulascc, Feb 28, 2015.

  1. athulascc

    Thread Starter Member

    Aug 15, 2014
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    I am going to design led torch using small watch batteries. ( this image type)[​IMG]
    I need to use push button instead of slide button
    problem is I can't use IC since here I have 3V only

    what is the best circuit for that
    assume led needs 50mA

    thanks
     
  2. athulascc

    Thread Starter Member

    Aug 15, 2014
    86
    1
    I have idea about 555 ic based circuit. but if I use it i think I need 5V
    also I need to know how to calculate the lifetime for a one battery of torch
    I can do it by measuring power requirements
    but I do not know battery details
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    What is the forward voltage drop of your LED?
    Look at the battery makers data sheet to see what is the maximum current that the battery can deliver. (I dont think it is even close to 50mA).
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The ML2016 can not deliver the wanted 50 mA.

    [​IMG]

    Bertus
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The capacity of that battery is only 18mAh or ~25mAh (depending who's figures you believe). So even if it could give ~50mA a charge wouldn't last long.
     
  6. athulascc

    Thread Starter Member

    Aug 15, 2014
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    ohh that a big problem
    so no matter then is there any circuit ?
    which can use push button
    once pressed led on
    then press off
     
  7. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    No "circuit" can make up for the fact that the battery does not store enough energy to do what you want.

    Look at all the available high-output flash lights. Do you see any that use a coin cell? Three AAA or AA is the minimum.
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  9. MikeML

    AAC Fanatic!

    Oct 2, 2009
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  10. athulascc

    Thread Starter Member

    Aug 15, 2014
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    yes. also that is use push button which can't keep turn on without force.
    is there any mechanical type push button once pressed turn on next press turn off.
    I know they are available but I need one that height is less than 3mm
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Why are you looking for that switch if the battery won't do what you want??
     
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    My working glasses uses two small coin cells and has a push button. No need to make just buy it.
     
  13. takao21203

    Distinguished Member

    Apr 28, 2012
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