This is my first time using arduino uno, so I have been following the adafruit guide on how to use a photocell to control an LED: Using a Photocell | Photocells | Adafruit Learning System. I have been following this example through adafruit exactly, all of the wires are hooked up according to the second diagram, but the LED still won't turn on.
I have to wonder if it may be due to the second resistor that is paired with the LED, as the stripes on the resistor I have do not match up with the one in the example diagram. The resistor that is paired with the photocell is brown black orange and gold, and the resistor that is paired up with the LED is brown black red and gold. Of course it could be another problem entirely, I just can't seem to pinpoint the cause.
Any advice you could give me would be greatly appreciated!
Hi and welcome.
The brown black orange means 1, 0, x 1000.
So that is 10000 or 10 K as stated in the example you found.
Brown, black, red is 1,0, times 100, which results in 1000 or 1K.
That 1000 is a bit high, but your LED would probably light up faintly.
The LED is a diode (Light Emitting Diode), meaning it is polarity sensitive.
It is supposed to have a long and a shorter leg, the short one is the cathode.
Cathode should be connected to GND (either via a resistor or not, as long as there is a resistor in there somewhere).
Most LEDs also have a flat side where this cathode is.
So check to see you haven’t reversed that LED.
If not, try to find a resistor of a lower value, lowest you could try is 220 Ohms; red, red, brown.
If you do not have a lower value but you do have another 1K, you can put 2 of those in parallel creating a resistor of 500 Ohms.
By the way:
Read that entire Adafruit page, the last section tells something about how an A/D converter works.
Even if you do not understand it right away, you’ll learn a bit about how things work.
This worked perfectly, thank you so much!