Atmega324P
$8.50
20x4 LCD
$18.50
16x2 LCD
$12.50
Breadboard
$7.95
Clear Breadboard
$8.50
Red LED 1.7v
$0.34
Green LED 2.2v
$0.34
Yellow LED 2v
$0.34
330ohm Resistor
$0.24
0.1uf Capacitor
$0.24
10k Potentiometer
$0.85
20k Potentiometer
$0.85
10uF Capacitor
$0.44
Jumper Wires
$12.00
Microcontrollers - Using Potentiometers and Understanding Voltage Dividing (Want
some Analog Voltages?)
Are you looking for a good device to test your ADC? Do you need a variable voltage
anywhere between 0 volts and the top voltage of your circuit? In this video, I show
how this is done. The potentiometer is just a fancy voltage divider. First, a good
understanding of the potentiometer is required.
The potentiometer is just a resistor. Don't believe me? Just measure the resistance
from the two outer leads with a multimeter. Remember to set it for ohms before you
make that test. You will see the total resistance at which the potentiometer is
rated (or for which it was designed). The resistance may not be exact, but it will
be close.
Now, try testing the resistance from the middle lead to the one of the outer leads.
Not the same resistance, huh! This resistance will be a portion of the total resistance.
Don't move that knob!! Test the middle lead to the opposite side lead and see what
you get. You guessed it. the measurement will be the other portion of the resistance.
So, if you added-up those two resistances, you will get the total resistance of
the potentiometer (the first reading that you did from the two outer leads).
Now you have a way to get any voltage from this potentiometer by grounding one of
the two outer pins and applying the "+" voltage on the other end pin. The middle
pin will provide the new voltage somewhere between the 0v (gnd) and the top voltage.
You can even check this on the multimeter. Just put one test lead on gnd and the
other test lead on the middle pin. Start spinning the knob and see what you get.