# 2 ways connecting a variable resistor?

Hello Everybody,

I want to connect 6 knobs (kohm) in arduino. I searched in various tutorials and i found two ways to do that. The one way is simply connecting a knob to analog-in, Vcc, ground. The other way is to put a constant resistor in the connection between knob and ground, and this resistor must be the same value as the maximum value of the variable resistor(knob). What is the difference between these 2 ways? Is there any difference if i connect all the 6 knobs or just one?

Use the first way, then you will get the maximum swing on the readings. The second way is for when something changes resistance but you do not have access to the centre tap. In other words it is a variable resistor not a potentiometer.

Is there any difference if i connect all the 6 knobs or just one?

Not sure what you mean. You only connect one knob to one analogue input, six knobs require six analogue inputs.

Do you mean each knob is a 1kOhm pot? Because connecting 6 across power is basically 167 ohms across your power supply, and at 5v that's going to be a constant drain of 30mA.

You should be using a minimum of 10-20kOhm pots for that purpose.

Also, is anyone else having trouble finding the "quote" button on the new forum software? ;)

thanks for the help. My question was closer to what oracle said. As i understand you mean 10k-20kOhms for each pot. questions: i. Why 167ohms for 6 pot with 1kOhm each one? ii. Are there any specific mA range for good operation?

For resistors in parallel, the resistance is the recipricol of the sum of the recipricols. When they're all equal values though, it's a special case where it's just the value divided by the number of resistors you have.

This is just a drain on the battery, so you want it as small as practical without the resistors being so big you have an issue with noise. 100kOhms for each pot would be fine too, but there's nothing wrong with 20kOhm.