Higher voltage?

Discussion in 'General Electronics Chat' started by taozeo, Mar 12, 2013.

  1. taozeo

    Thread Starter New Member

    Nov 11, 2010
    4
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    Is it possible to build up a higher usable voltage via a capacitor from a small solar cell?

    What I'm trying to do is build up 1.5-2.0v from a 0.5v solar cell within a capacitor to use after it achieves this higher voltage. Is this possible? Unless I misunderstand, this is how stun guns work, right?
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,452
    3,371
    Very possible. Google joule thief.

    Also look at the following chips:

    LTC3105

    LTC3108
     
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  3. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    It's difficult to step up 0.5V since it is so low and below the turn-on threshold voltage of typical transistors. Typically several solar cells are placed in series to get the desired voltage.
     
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  4. taozeo

    Thread Starter New Member

    Nov 11, 2010
    4
    0
    Thank you, MrChips! These chips appear to do exactly what I wanted. I wish I would have known about them before I ordered the 1381's IC's based on the "Miller Solar Engine" circuit I found here: http://www.solarbotics.net/library/circuits/se_t1_mse.html I've build this circuit and cannot seem to get the capacitor to charge up beyond the supply voltage of the solar cells... any advice on this? I'm hoping to make this work without having to purchase additional parts ($5 part with $10 shipping!)
     
  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Where does it say that this circuit increases the capacitor voltage above the solar cell voltage? They are both in parallel.

    In general google for "solar cell energy harvester". There are many new developments available. ex:http://www.ti.com/lit/ds/symlink/bq25504.pdf
    Pay attention to the package when buying these chips, they come often only on QFN/DFN packages, difficult to solder without the right equipment.
     
    Last edited: Mar 12, 2013
  6. taozeo

    Thread Starter New Member

    Nov 11, 2010
    4
    0
    Thanks, Praondevou, I thought that strange as well. Maybe I misunderstood but if you read the second paragraph on this version: http://www.solarbotics.net/library/circuits/se_t1_1381.html it states the 1381 increases the voltage from 0.2v-0.3v to a much larger value in order to run a motor from a small solar cell... so I assumed it would work.

    Thanks for the link, I'll check it out.
     
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