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A rotation potentiometer, often referred to as a “pot”, is an analogue input device that, when used as a voltage divider, varies the voltage from a source by rotating a knob. When used with the Kookaberry, it varies the voltage continuously (therefore it is an analogue signal) at an input connector in the range 0-3.3 volts in one complete 300 degree rotation.
Specification
- Supply Voltage: 3.3V to 5V
- Interface type: Analog
- 300 degree rotation sensor
-
Size:22x31mm (0.87x 1.2 in)
How does it work?
The following electrical explanation relies on this Random Nerd Tutorials]
A potentiometer is a three terminal device, where the full voltage is present across two terminals (V and Ground (earth)) and the third terminal presents a variable voltage (always less than V) relative to Ground depending on the amount of turn of the knob.
This potentiometer is used as a voltage divider. One of the outer pins is connected to the GND, the other to the positive power supply voltage Vcc and the middle pin is the voltage output.
When the potentiometer is used as a voltage divider, the wiper position determines the output voltage. When you have the potentiometer connected this way, you have the following circuit:
Basically, the voltage divider is used to turn a large voltage into a smaller one.
The output voltage can be calculated using the following equation obtained from Ohm’s Law:
For a more detailed electrical explanation, go to this Sparkfun tutorial on voltage dividers
How a potentiometer is used
Potentiometers come in a variety of packages, and have many applications of their own. They may be used to create a reference voltage, adjust volume of an output signal like music from a radio, measure position on a steering wheel or joystick to send to wheels or a servo, or in tons of other applications which require a variable input voltage.
Connect it to the Kookaberry and check out the Start Your Engines Tutorial to show how it can be used to simulate the filling of a petrol tank.
