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Need Help With LED's

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guillermo

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I am a novice and I'm trying to hook up a series of LED's that are controlled by a photoresistor so that they will increase in brightness as the room they are in brightens.

The one thing though is that when the room goes dark I want the LED's
to be on to a brightness that I would be able to control with a
potentiometer. Any ideas on how I can do this? Any help is of course
greatly appreciated.

Bill
 
A fixed resistor in parallel with the photo resistor will set a minimum current (and brightness) that you can adjust. If you use a potentiometer as a rehostat, put a fixed resistor in series so you don't blow the diodes by running the pot to zero ohms.
 
Here is a circuit I designed for someone else. Resistors R6 & R7 and D1 set the minimum light level brightness. R6 & R7 could be replaced with a 50k pot if you wish.

I don't recall what colour display he used. So you may have to make some changes if your display is different to his. R1 and R5 set the brightness range and the 56 Ohm resistors set the maximum brightness. These resistors must also be chosen so the maximum current rating of the display is not exceeded.

Len
 

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