Light and dark sensor need help

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kamisochino

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I'm trying to make a dark and light sensor (see attached images). SW1 is for setting the device to light or dark sensor mode and VR1 is for the sensitivity.

I've tried it on a breadboard and everything works fine so i decided to put it on a pcb and made my own layout.

When I tried testing it, when i put it on light sensor mode, it senses the light but only a little. LED dims a bit when i turn off the light but it doesn't go off unlike when i tried on a breadboard. VR1 also doesn't do anything on this mode.

When i put it on dark sensor mode, nothing happens. LED is just on the whole time. When i adjust VR1 it only changes the brightness of the LED.

Can anyone please help me? Can anyone verify the layout i made?

Thanks a lot.
 

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hi,
The first error on the PCB is R4 is not in series with the LDR. [C of the switch]
Check the switch, the pin coding on the schematic is different from the PCB coding
E.
 
thanks! I've corrected it now (see attachment). also i forgot to add a ground connection at B and D. The light sensor part is now working great. but the dark sensor is still the same.
 

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When i put it on dark sensor mode, nothing happens. LED is just on the whole time. When i adjust VR1 it only changes the brightness of the LED.
Click to expand...
Well that's not 'nothing happens' . Assuming dark mode has the switch in its lower position and the pot is set at minimum you have 1k from the transistor base to ground. The photocell would have to have a resistance greater than ~ 1k * 9/0.6 = 15k for the base voltage to be reduced below the point at which the LED current is reduced. For sensitive photocells that would require almost complete elimination of light. Perhaps a small amount of light is still reaching yours? If the pot is set > minimum the situation is worse.
 
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