Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Spiffyguy on April 08, 2008, 10:18:23 AM
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I am fair new to electronics so I want to make sure I have this right before I start soldering stuff. I am trying to verify the correct resistor for my photocells. I have a medium photoresistor from Radio Shack. I tak emy multimeter and set it to 20kohms. it reads 2.57. so this is really 2570 ohms or 25700 ohms? my dark reading I set the meter to 200k and it shows a reading of 67.5 so I am not sure what the exact reading is. Still figuring everything out. Near as I can figure I need a 5k resistor for the photocells. Is this right?
Thanks
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man when u set ur multimeter to 20k that tells u that the max reading which ur multimeter can read is 20k in short now ur multimeter is ranged between 0-20 k a reading of 2.57 would mean 2.57 k or 2570 ohms and ur reading in dark is 67.5 k ohms
now getting into the mathematical parts ur resisitor value should be ~(2.57*67.5)^0.5 K OHMS
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What is the ^ symbol in your equation?
If I input 2750 as my minimum and 67500 as my max into the resistor spread sheet it shows me i need a 5k resistor. Just want to make sure before I buy the wrong one.
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well if u look in the tutorials ull know that ^ implies power when i say 2^2 it means 2 to the power 2 which is equal to 4