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Auto Intensity Control of LED Lights

Discussion in 'LEDs and Optoelectronics' started by experimenter, Feb 21, 2016.

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  1. experimenter

    experimenter

    3
    0
    Feb 21, 2016
    I have been experimenting with this circuit in pspice from:

    http://www.electronicshub.org/auto-night-lamp-using-high-power-led/

    I have redesigned it to use one transistor instead of two. See pspice simulation screen images attached (the schematic files are also attached).

    Any thoughts on this?

    You can change the resistor values if more LEDs are required.
     

    Attached Files:

  2. Alec_t

    Alec_t

    3,060
    834
    Jul 7, 2015
    Welcome to EP!
    In the single-transistor circuit check the LED current. It is far too low.
    Neither circuit has hysteresis, so the LEDs are likely to flicker in response to small changes in ambient light level, e.g. at dusk and dawn or in cloudy weather.
     
  3. experimenter

    experimenter

    3
    0
    Feb 21, 2016
    Thanks. That is beyond me I'm not very knowledgeable about electronics circuit design. I attach another attempt at a circuit. This time I tried to get it to oscillate with a sine wave. Unfortunately the voltage seems to be far too small.
     

    Attached Files:

  4. experimenter

    experimenter

    3
    0
    Feb 21, 2016
    I have changed the design slightly so the current through the diodes is now about 12mA. The funny thing is the current seems to be going backwards through the transistor.. (out of instead of into the collector)
     

    Attached Files:

  5. Alec_t

    Alec_t

    3,060
    834
    Jul 7, 2015
    The collector current polarity depends on the transistor bias conditions.
     
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