Near Intersection of I-35 & I-90 Southern Mn. | You have summed it up very well. On my 9770, the feeder house turns a Pot as the feeder house is raised or lowered. Deere mounted this on the left side of the combine near the pivot point of the feeder house. This changes the voltage on a signal wire which leads to the combine system where it can make decisions based on the voltage it receives.
When I added the Ag Leader system, they supplied an electrical Tee that was a convenient way to tap into that signal wire. Thus the Ag Leader also receives this voltage based on the feeder house position. It makes its own independent decisions as what to do with the information.
When I added the Truesight feeler steering controller, they included yet another electrical Tee for their purposes.
This means that the voltage signal from the feeder house sensor goes to three independent devices on my combine. The Ag Leader starts/stops its acre counter based on this value. The Headsight feeler steering system kicks out when the feeder house is raised.
A "Pot" has 3 terminals. The outer terminals are connected by a curved path made of a resistive material. The total resistance from one end to the other can be different values but 10K ohms is common. The third center terminal is connected to a "wiper" on the end of the shaft usually controlled by a knob or some type of mechanical linkage.
Much like a windshield wiper on a car, this wiper can touch the resistive curve at different places along the curved path. If 12V is connected to one of the outer terminals and ground to the other outer terminal then the wiper could pick up 0-12 volts depending on where it is touching the curved path. If the wiper touches the curved path close to the center it would pick up around 6 volts. If it was closer to the 12V end then it would pick up a higher voltage, closer to the ground terminal then a lower voltage.
With the Ag Leader add on feeder house assembly that I used with an older combine, a rod, chain and spring were used to twist their Pot. Again the voltage on the wiper terminal would vary depending on the height of the feeder house. A light chain to a rod would twist the Pot as the feeder house was lowered. When the feeder house was raised a spring kept tension on the shaft causing it to rotate the other direction.
When a Pot is used, an analog signal is produced. It is not ON nor OFF but a range of values between. This voltage can be used with an indicator or some device to control something.
If the goal of the project is to control something then often a certain voltage would be used to make a decision. So your example of doing this at 1.3 V is correct thinking.
With modern digital electronics, this voltage is usually fed to a device called an ADC meaning Analog to Digital Convertor. This device takes the possible range of voltage values such as 0 - 12 volts in this example and converts them to an actual number often within the range of 2^n - 1. So the voltage range might be converted to a number between 0 to 255, 0 to 1023 etc. Then the digital device can display or make decisions based on the value.
This is in contrast to the homemade switch that my friend and I made. Our barn door hinge, push button switch and spring were actually "digital" since the circuit was either ON or OFF with no values in between.
The small cheap microcontrollers that I fool around with contain several of these A to D converters allowing all kinds of possible inputs.
Edited by tedbear 4/3/2024 07:33
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lift switch recomendation
