First of all I truly appreciate your input. What I am trying to achieve is to find potentiometers (need a pair of them) that I can setup with the accelerator pedal of a car that I would like to work on. The voltage outputs of the potentiometers will be transmitted to an engine control unit and will be used to move a servomotor to change the position of the throttle valve and adjust air intake. I also plan to use another pair of potentiometers near the throttle valve to monitor its position.
I had a look at "SAJ2515 with "F" aluminum handle" on this webpage:
I was thinking to get the 20K or 10K potentiometer just for saving Amps of current, but I am not sure whether I am on the right track or do I need to take something else into account?
Just a heads up. Forum Terms prohibit the discussion of topics if they fall under one of the following categories:
- Spy tools
- Personal or public risk
- Offensive or threatening behaviour
- General off-topicness
This may very well fall under personal or public
risk depending on the scope of your project.
I will give you some more generic details, but nothing specific to automotive until you can provide more details about what roles the modification will have. (ie, Will this be for a Go-Kart, or for a car that will be travelling on public roads?)
Potentiometer number 1, which will be connected to the pedal will, as Duke mentioned most likely be connected directly across 12V. You had asked about different ranges. Well, this is one reason. A larger value potentiometer will let less current through it, and heat up less. Picking a value of 1K or higher will be sufficient here. Please note that the 1K will constantly waste 12mA as long as it is connected to power. Simply using a 2K will drop this to 6mA. The important part here is that the middle pin of the potentiometer will be able to vary anywhere from 12V to 0V. However, it can't provide much power, so this 0-12V signal needs to be connected to another circuit to interpret it and do something with.
For example, you could use it to control a PWM signal. (Which is a square wave that can vary it's time high, verses it's time low. This relationship is what a servo uses to position itself, or how you can control average power to something like a light or motor.)
As far as the servo is concerned, depending on how you plan to connect it, you may need a beefy servo, but that is for you to determine. You need to make sure the servo will have enough torque to do the job.
One quick recap.
I had copied and pasted a portion of the terms above due to the nature of the work involved. If your sensor or circuit misbehaves or get damaged, it could cause unexpected results. One such failure could cause a 'runaway' condition, which if you are unaware is common with older diesels.
Make sure you take more than the necessary safety precautions to ensure that you remain in control of your machine before you do any modifications to it.