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Auto Intensity Control of LED Lights

experimenter

Feb 21, 2016
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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.
 

Attachments

  • LightDependentIntensityControlLeds PSpice Schematics Source.zip
    3.4 KB · Views: 33
  • LightDependentIntensityControlLeds.png
    LightDependentIntensityControlLeds.png
    336.7 KB · Views: 46
  • LightDependentIntensityControlLeds2.png
    LightDependentIntensityControlLeds2.png
    252.1 KB · Views: 45

Alec_t

Jul 7, 2015
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Jul 7, 2015
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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.
 

experimenter

Feb 21, 2016
3
Joined
Feb 21, 2016
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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.
 

Attachments

  • a circuit - pspice schematic.zip
    1.3 KB · Views: 30
  • a circuit.png
    a circuit.png
    564.2 KB · Views: 85

experimenter

Feb 21, 2016
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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)
 

Attachments

  • LightDependentIntensityControlLeds Schematic.zip
    3.4 KB · Views: 33
  • LightDependentIntensityControlLeds2A.png
    LightDependentIntensityControlLeds2A.png
    320.9 KB · Views: 43
  • LightDependentIntensityControlLeds2B.png
    LightDependentIntensityControlLeds2B.png
    331.3 KB · Views: 45

Alec_t

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