Author Topic: Photoresistor tutorial  (Read 1844 times)

0 Members and 1 Guest are viewing this topic.

Offline Blood-manTopic starter

  • Jr. Member
  • **
  • Posts: 18
  • Helpful? 0
Photoresistor tutorial
« on: August 09, 2009, 09:50:06 AM »
I'm really confused by the photoresistor tutorial. I used analog multimeter and biggest photoresistors from Radioshack set. I get 6.703 KOhm. Is it OK? And can you explain me why I need to solder the end of photoresistor to the ground? I thought that it got to be analog output, because microcontroller not gonna read the ground, so it don't make any sense.

Offline sonictj

  • Supreme Robot
  • *****
  • Posts: 416
  • Helpful? 11
Re: Photoresistor tutorial
« Reply #1 on: August 09, 2009, 10:06:10 AM »
a photoresistor is a variable resistor.  It changes its value with different amounts of light.  You are simply creating a voltage divider circuit where you ADC channel connects between the two resistors.

gnd-------Photoresistor--- to ADC ----normal resitor---+5V

or

+5V-------Photoresistor--- to ADC ----normal resitor---gnd

the only difference is whether the voltage will increase or decrease which more light

 


Get Your Ad Here