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What does it do?
| The rotation sensor uses a potentiometer to sense rotation. It can also be used to produce a variable voltage. |
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How does it operate?
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Click on the circuit diagram to download a Livewire file of the Rotation Sensor that you can investigate and add to your own circuit. |
As the potentiometer dial is turned, the resistance of the output signal voltage gradually increases from 0V to the supply voltage Vs. The rotation sensor acts as an input voltage unit.
The rotation sensing circuit uses a potentiometer or potential divider:
Potentiometers can be mounted on the PCB or on the case. |
 A potential divider |
The resistance across the potentiometer remains constant. However, as the dial is turned the resistance of R1 falls and the resistance of R2 increases. This causes the output voltage at the wiper to rise. Turning the dial the other way reverses this. |
Possible applications
- Checking how far something has tilted
- Letting the user vary something by providing a variable voltage to an analogue electronic processing unit
Making
How part of the PCB might look
Testing
Make sure that the voltage signal going out (on the green PCB track) changes as the knob on the potentiometer is turned.
Fault finding
If there is a fault, check that:
- The resistance of the potentiometer between the 0V line and the Output signal line changes from zero to 100k as the knob is turned.
If there is a fault, check the tracks and solder joints.
Alternatives
- Tilt switch – simple but only gives a digital output signal.
Web links
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