Photoresistor with NE555

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miyayoung
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Photoresistor with NE555

Post by miyayoung »

I would like to build a circuit with two blinking LEDs using a NE555 (here is thene555n datesheet) timer and a photoresistor. In the schematic below the blinking frequency becomes higher when more light shines on the photoresistor (represented by the photodiode D1 in the schematic; there was no symbol for a photoresistor) and lower when there is less light. What I want, however, is the opposite: I want the blinking frequency to become higher when there is less light and lower when there is more light.

Can anybody tell me how to change the schematic so that it does what I want? I have to add that I'm not really advanced in electronics yet, so please understand if I did not provide information you need.

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Benj
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Re: Photoresistor with NE555

Post by Benj »

Hello,

The photo diode will form half of a potential divider with a fixed resistor forming the second half. Simply swap the position of the photo diode with the resistor to invert the operation based on brightness.

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