Introduction: PicAxe LED Dark Detector

First, I saw an interesting Instructable titled "Light Sensing LED - PicAxe Version" by Bot1398. I tried to reproduce this project but just couldn't get it working. However, I used much of Bot1398's circuit to make my own circuit that was similar and also worked.

Step 1:

Notice that the schematic reveals TWO LEDs instead of just one. I decided that maybe the input would be higher and more distinct using two LEDs. I also used a separate output and LED for my "display." The resistor for this LED is 330 ohms while the "pull down" resistor for Leg 2 is 10k ohms. I tried more than a few times to make the PicAxe code match the electronics of the schematic and then downloaded this to the PicAxe 08M2 microcontroller.

Step 2:

With the battery connected with normal lighting, the separate yellow LED doesn't light at all but when I cover the two sensing LEDs with my hand (or shut off the overhead light), the yellow LED blinked about 5 times a second. This project was a success as far as additional learning for me but a regular photocell might work better for a serious project...


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