The common potentiometer has a problem with poor contact on the slider shaft.
So I thought about making an adaptation similar to the one found in automobiles.
As I understand it, the car's gas pedal uses 5 volts on the power of both lanes, and the output of the first lane varies between this range from 0 to 5 volts. But the second track produces half the value of the first, from 0 to 2.5 volts.
It seems obvious to me that the objective is to avoid a possible false reading if they were outputs with the same signals and a short circuit would occur in the two outputs of the potentiometer tracks.
As the original circuit would not be changed, then the adapter circuit needs to deliver the same signal that the potentiometer (one track) does, ie analog from 0 to 5 volts.
Initially I thought about using a PWM output, but I think the low pass filter can make the response a little slow,
Then I thought about the DAC MCP4725, but it's an additional cost,
Finally thought of R2R type DAC. Maybe using a Rail to Rail op amp on the output.
The cheap ones do. You can buy much better quality pots, intended for decades of reliable service, for example from Allen Bradley. They have been around for at least 50 years.
Exactly, the originals are from the cheap models, in addition, moisture enters the potentiometer track, and also because of this the problem of using direct voltage in the potentiometer track must cause even more problem of bad contact.
About using something amateur, I don't know if it would be possible to consider a professional device when this type of problem occurs, if they used a high quality, shielded potentiometer, those 50 years old, I wouldn't have come here to comment on the car accelerator pedal.
I'll see if I can get one of these sealed for testing,
About usage, it would be for DC motor speed control, the output of 30V about 250W which is manually controlled via potentiometer.
Thanks for the tips, but the objective of the question is still open, which is:
The use of a double potentiometer being monitored by a microcontroller,
Make the output be only one and be compatible with 0 to 5V,
Generate an alarm when it notices failure (float ) of the signal input of a lane, but do not fail to make the output (0-5V) while there is one of the lanes with good contact.
I'm not talking about lines of code yet, I'm just discussing the working principle,
About writing the program, I believe I could do it,
About how the car accelerator pedal works, I read this operation in a test description of a real part, I didn't invent it,
I suggest you research about it, if you are interested and have the time, it seems to me to be very interesting to know about the throttle potentiometer and it also seems that another potentiometer is used in the electric steering, but I haven't researched yet about the electric steering
Well, it depends what you are using the potentiometer for.
If it is, for example, in a feedback loop of a boost converter then you wire it in such a way that, in the event that the wiper fails to make contact with the track, the maximum voltage is delivered back, effectively shutting the device down. In that case it is simply a matter of bridging the wiper terminal and the high side being measured.
There are sometimes alternatives to potentiometers in position detection systems where reliability is critical. Here is one used in an angle of attack sensor for a passenger aircraft using a rotating coil: Satcom Guru: Angle of Attack Vane Failure Modes
Hi,
Some of the automotive throttle position pots have their two ganged potentiometers wired so one wiper goes 0 to 5V and the other 5V to 0.
So if you add the to signals together you always get 5V, otherwise there is a problem somewhere.
It is similar to a common power control whether linear or PWM output, it doesn't matter, the issue is the failure of the potentiometer slider.
One thing I thought about is the response time issue, I believe that the motor rotor has a mass that generates an inertia, and that maybe it would even be possible to use a DAC with PWM, maybe using a low-pass filter not very damped.
About TPS, this is not the case. The TPS is used in the throttle body inside the engine compartment, in the engine's air intake.
The double potentiometer I am referring to is the one used on the pedal, which the driver steps on to accelerate the car, and which is next to the brake pedal.
Sorry for the incorrect use of words, the word was suggested to me and I ended up leaving this one,
Anyway the TPS sensor there is a model that is not mechanical, maybe it is optical or magnetic I don't know well.
But my brother had problem with his car's TPS after washing his car engine.
I ended up finding an alternative TPS model that doesn't suffer from this water infiltration problem.
I'll see if I can get one of those special TPS to open and see what the internal build looks like,
It might even be possible to adapt one of these TPS in my case.
In applications where a direct current...is recommended that you connect the negative line to the resistance element and the positive line to the sliding arm.
Well, yes, you have said you are connecting a motor. Would you rather see, in a failure situation with the potentiometer, the motor running at 100% or at 0% ?
To prevent the RPM from increasing, I thought of using a pull down resistor, but I believe that using the two-lane potentiometer idea is more suitable.
