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### Topic: Voltage Divider Necessity for Analog Sensors (Read 3169 times)previous topic - next topic

#15
Looks good.

#### TomGeorge

#16
##### Jul 10, 2016, 10:32 am
Thank you Master Po.
Everything runs on smoke, let the smoke out, it stops running....

#### ph77

#17
##### Jul 10, 2016, 10:35 am
Try it out yourself... Ohm's law is R = U / I. Solving for U yields U = R * I. This is the voltage drop of a resistor. Now connect a 10K resistor across +5V and an input pin. Measure the current by placing a multimeter in series. Notice that the current is very close to zero. Thus the voltage drop across the resistor is almost nonexistant. This is because, as others have pointed out the input pins have very high input impedance. Repeat the experiment with other resistor values if you like

#### raschemmel

#18
##### Jul 10, 2016, 10:40 am
Good sanity check PetriH

#### mrburnette

#19
##### Jul 10, 2016, 05:57 pm
Yawn...

We're in the 21st century and I'm an old EE and the days of classwork, lectures, and lab can now be done in just minutes on your PC.  You will get a clear understanding of what is happening, you can use your fancy calculator to verify, but the value of today's tools is the instant feedback.

Paul has done a remarkable job of making learning (re-learning) fun: http://falstad.com/

For electronics, the reference is: Circuit Simulator

Ray

#### raschemmel

#20
##### Jul 10, 2016, 07:24 pm
Thanks MrBurnette !

I will check it out.

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