What is the most efficient approach to make an UV LED torch with a 5V source?

Discussion in 'The Projects Forum' started by FranciscoB, Jan 24, 2017.

  1. FranciscoB

    Thread Starter New Member

    Feb 8, 2014
    23
    1
    I would like to build a small torch that would "dry" this sort of gel:

    http://www.ebay.co.uk/itm/252371823062

    I have one of these powerbanks:

    http://www.ebay.co.uk/itm/Portable-...-Battery-Charger-With-Key-Chain-/231777736401

    And a set of these:

    http://www.ebay.co.uk/itm/50pcs-5mm...317602?hash=item338ae0c1e2:g:NJ4AAOxyJX1S~DPO

    I also have an assortment of discrete components like resistors, LM317, transistors, etc.

    Instead of buying yet another device, how should I build an efficient circuit to light these LEDs (just a few)? Constant current driver? One resistor per LED?

    Thank you
     
  2. crutschow

    Expert

    Mar 14, 2008
    20,070
    5,653
    What is the ampere-hour rating of that powerbank?
    How much current will the LED(s) take and how long do you need to power them?

    The most efficient is to use a switching constant-current circuit to power the LED.
    For example, here's a relatively simple example circuit using a common comparator IC to do that:
    upload_2017-1-24_15-21-39.png
    Otherwise just use a resistor in series with the LED.
     
    Last edited: Jan 24, 2017
Loading...