transpose to 12v

Discussion in 'The Projects Forum' started by happysoul, Oct 12, 2014.

  1. happysoul

    Thread Starter New Member

    Sep 9, 2014
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    Hi Guys and Gals was wondering if someone could transpose this 5volt circuit to 12volts
    thx
    upload_2014-10-12_17-12-19.png
     
  2. crutschow

    Expert

    Mar 14, 2008
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    What is the purpose of the circuit?
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    What is the rated forward voltage of each LED?
     
    Last edited: Oct 12, 2014
  4. happysoul

    Thread Starter New Member

    Sep 9, 2014
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    the forward voltage is 1.8v to 2.1v, the purpose is the led on the base is a flickering led, like a candle but not very bright hence the 1 watter.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Replace the 620 Ohm with 470 Ohm. Replace the 2 Ohm with 39 Ohm. Use a 2N2907 (or similar) for the PNP.
     
  6. happysoul

    Thread Starter New Member

    Sep 9, 2014
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    Cool, Thank you Alec I'll give it a whirl, I'll let you know how it went.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    The brighter LED should flicker along with the dimmer one, which acts like a controller. Do we know that it works OK at 5V?
     
  8. happysoul

    Thread Starter New Member

    Sep 9, 2014
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    Yep works perfect on 5v, I tried it with the resistor changes only have a bc327 at home, but doesn't work, the brighter led just stays on, no flicker, maybe the transistor
     
  9. wayneh

    Expert

    Sep 9, 2010
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    It's not the transistor (assuming it isn't damaged and you have the pins right). You need to tweak the base resistor to get it to turn the transistor on and off with the flicker. Too small and it's always on, too large and it won't go off.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Good point, Wayneh. Perhaps try ~1k-2k?
     
  11. happysoul

    Thread Starter New Member

    Sep 9, 2014
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    Yeah good idea I'll try a pot to get it right, thanks guys
     
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