Quote:
|
Originally Posted by Max Lobovsky
For example, how can the RC possibly tell if its connected to a 10k ohm in the mid position, or a 5k ohm at the max position?
|
A potentiometer is really just a variable voltage divider. Using Ohm's Law (voltage = current multiplied by resistance or V=IR), then at 5 volts there is (5V / 100K Ohms) or 50 uA of current flowing across the pot. Now, if you set that pot at its mid-point, you have 50K on either side of the resistor. Again, using Ohm's Law, you have V = (50uA * 50K Ohms) = 2.5 volts of a drop across that half of the potentiometer.
If you repeat this exercise for a 10K pot, you'll find that if it's set at its mid-point (5K Ohms on either side), you still have 2.5 volts dropping on either side. So in either case (10K or 100K), with the wiper set at mid-point, the RC sees 2.5 volts. The only difference is that at 10K more current is flowing. The reason they limit you to no less than a 250 Ohm pot is because any pot with a smaller resistance will draw more current than the RC is capable of providing.
Hopefully at least some of that made sense
