glowing and dimming LEDs with a transistor

Discussion in 'General Electronics Chat' started by michael page, Oct 29, 2013.

  1. michael page

    Thread Starter New Member

    Oct 29, 2013
    Hello folks, Im making a project that requires a pair of LEDs to glow and another pair to dim upon receiving an envelope signal from a synth. I have breadboarded a circuit that works where a npn transistor receives the signal allows a pair of LEDs to glow, then an LDR's resistance drops shorting a second pair of LEDs making them fade out.
    It works pretty well but seems like it might screw up the LDR quite quickly. Is there a better way of doing this?

    my current diagram...
  2. wayneh


    Sep 9, 2010
    If it works, I don't see a problem. The LDR is connected to the battery thru 12kΩ of resistance. As long as this is within the specs of the LDR, it'll be fine.