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My Christmas time project was to learn how to control a motorised potentiometer using a Crumble. These are used in mixing desks and can have up to 100 mm of movement. I found it quite easy to do, allowing around 0.5 mm positioning resolution and better than 1 mm repeatability. The output from the Crumble is a bit low in voltage terms, they are designed to work from 6V, but so long as the speed % was more than 60, the motor did not stall. The potentiometer side was connected between 5V and 0V at the ends and Analogue B was attached to the slider position output.
I used a Poundland £1 USB power supply for the project.
Two could be connected up to make an XY stage.
There are two tracks on each potentiometer, so the Crumble could be used to control resistance in another isolated circuit…so you could have a project where a mic is connected to your Crumble. You clap your hands into the mic and the Crumble moves the pot, which is also the volume control in your radio or whatever…clap your hands again and the volume goes up again.
Can have a lot of fun with these!
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Here are some pics…see the divisions I marked, 1 cm corresponds to a voltage change of about 0.5 V. Yellow wires go to the motor, brown to the pot connections. The USB brick gives a good 5V supply.
The simple code in this example waits for A to go high. Then if the slider is less than 2 cm from the bottom end, the motor moves it to the 8 cm position, waits 5 sec, then takes the slider back to the 2 cm position.
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I’ve played around with this project a bit more and added a second pot (but with the motor not attached) connected to another input. With this little programme, you can move the slider on this input pot and when you make A go high, the Crumble moves the motorised pot to the same position as the input pot 🙂
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