The potentiometer, the missing control.

Tuesday, November 2nd, 2010

A potentiometer is basically a device that varies the voltage of a circuit and by doing so can act as a control for an electric device, in our case a motor on an electronic gas valve and a blower motor. In many cases the potentiometer does not control the actual device but is used as a passive control and some other device will actually control the motor. They are not normally used to directly control a circuit because they would have to draw the same amount of energy as the regular circuit and that can be expensive, bulky and dangerous depending on how much power the original circuit is drawing. They do make large ones, but more often a small potentiometer is used and then a circuit in a larger control reads the output of the potentiometer and adjusts the motor accordingly. There are other advantages to using a smaller potentiometer besides expense, size and safety. The circuit that reads the potentiometer can integrate other things such as thermal protection, overload protection or, in the case of our motor on the electronic gas valve, it can make sure that the motor doesn’t turn the valve too far. The potentiometer is important to us because it will allow for the manual control of the temperature and airflow in the roaster during the roasting process. I have integrated these controls into the roaster because the number-one complaint I hear about fluid-bed roasters is a lack of control. Plus, in my opinion, to truly be a specialty or artisan coffee roaster you have to have control over as many of the variables of your roast as possible and these potentiometers will help us do just that.

1 Comment so far

  • Brian
    November 15, 2010

    You definitely ‘hit the nail on the head’ by solving the lack of control in the fluidized bed process. It’s the definitely the Kryptonite of our Sivetz roaster.

One Response to “The potentiometer, the missing control.”

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