Only if you choose the 5V version. In your pic it's a 3.3V version.So if my batteries are supplying greater than 5.4vDC this little unit should give me 5VDC
Only if you choose the 5V version. In your pic it's a 3.3V version.So if my batteries are supplying greater than 5.4vDC this little unit should give me 5VDC
Rather than try to modify a pot like those you have listed a simple trip to an automotive junk yard should yield dozens of TPS units. Just find one easily modified for your application. Also places like Amazon list dozens of actual TPS sensors with many less than $12 USD in cost. Another solution is to use a linear motion potentiometer similar to these. The actual value of the pot is not all that critical. Any 5K or 10K pot should do fine. The lower the value of the pot the greater the current through the pot if you are current conscious for battery life. Do you know the input resistance of your A/D converter (your display)? It is likely high so again any 5K or 10K pot should do fine.
You may also want to keep in mind that a 1 Turn pot typically is not a 360 degree rotation, check an actual manufacturers data sheet as most are 260 / 270 degree rotation.
Ron
Only if you choose the 5V version. In your pic it's a 3.3V version.
Yeah, I was sort of thinking converting rotational to linear, much like what you see attached to a servo motor using a simple linkage. Thus a simple linear pot could be used.Reloadon automotive TPS sensors are way too big for a 25cc engine. but thank you, also I can not use linear as I need a rotational movement.
Yeah, I was sort of thinking converting rotational to linear, much like what you see attached to a servo motor using a simple linkage. Thus a simple linear pot could be used.
I suggest you just start with the pot you get, interface it, and then see what you get. It looks like from your earlier screen shot that your OSD software solution allows you to scale what you get to what you want which is 0 to 100% on your display. You can use a 0 to 5K pot, a 0 to 10K pot the output will be the same. The only change will be the current through the pot.
For example you apply 5.0 V across the pot with a 5K pot the current through the pot will be 5 V / 5,000 Ohms = 0.001 Amp or 1.0 mA. Using a 10K pot it will be 5 V / 10,000 Ohms = 0.00050 Amp or 0.5 mA. The wiper voltage out will be the same about 0.0 to about 5.0 Volts. All assuming your OSD (A/D) has a very high input impedance which most do.
Your pot will have let's say "X" amount of rotational travel and for the total travel the pot will output 0.0 to 5.0 volts (approximately). Each 1/4th travel will be equal to about 1.25 volts. So here is what you have:
Single-turn pot
Single rotation of approximately 270 degrees or 3/4 of a full turn
Note the use of "approximately" as basic inexpensive potentiometers are not quite precision instruments.
Anyway it looks like your OSD software (A/D Converter) allows you to scale your inputs which is what you want to get your 0 to 100% of throttle position.
Ron
You may want to keep that in mind for life span as well as good repeatability.A good quality cermet pot should offer longer life than a cheap carbon track one.
Something else you can do is place a resistor above and below your pot. Just as a quick example, using a simple ratio, if I place a 5K resistor between 5 V and the upper leg of the pot and a 5K between the lower leg and ground my pot range would be about 1.66 V to 3.34 V. The resistances can be changed to get a lower limit above zero and an upper limit below 5.0 Volts. For what it's worth you could use a few pots and adjust to whatever you want for the TPS range.
The overall accuracy and resolution of your display will be a function of your OSD A/D converter. For example a 12 bit A/D conversion will yield 2,048 bits. So if the A/D has a 5 volt reference then you get 0 V = ) Bits and 5.0 Volts = 2,048 bits. Therefore 5 Volts / 1,024 bits = 4.8 mV per step change. That is the resolution.
Ron
So we have a pot with a total of 270 degrees of rotation. The throttle body going from closed to WOT (Wide Open Throttle) has a span of 90 degrees of travel or 1/3 of the pot 270 degrees. With 5 Volts applied any given 90 degrees of travel of the pot will give a voltage span of 1/3 of 5.0 or 1.666 volts. That span being as good as it gets. You can for example mechanically adjust your pot so it starts at 1/3 rotation which is 90 degrees which would be 1.666 volts out and at WOT the pot would be at about 3.332 volts. So 0.0% = 1.666 Volts and 100% would be 3.332 volts. The span is always going to be 1.666 volts or 1/3 of the 5 volt reference. Adding resistors in series with the pot will only decrease that span.What I need ideally is a voltage of
.95v when the pot wiper is at 90 degrees,
and 4.66v when the pot is at 180 degrees
with 5 volts applied to the pot.
Following some thought here is the problem you are going to have with your numbers.
So we have a pot with a total of 270 degrees of rotation. The throttle body going from closed to WOT (Wide Open Throttle) has a span of 90 degrees of travel or 1/3 of the pot 270 degrees. With 5 Volts applied any given 90 degrees of travel of the pot will give a voltage span of 1/3 of 5.0 or 1.666 volts. That span being as good as it gets. You can for example mechanically adjust your pot so it starts at 1/3 rotation which is 90 degrees which would be 1.666 volts out and at WOT the pot would be at about 3.332 volts. So 0.0% = 1.666 Volts and 100% would be 3.332 volts. The span is always going to be 1.666 volts or 1/3 of the 5 volt reference. Adding resistors in series with the pot will only decrease that span.
You can increase the voltage to for example 10 volts which will just double the numbers so you would have a span of 3.333 Volts for each 90 degrees of rotation. Keep in mind that throttle position sensors are designed for what they do in that most throttle bodies only have about 90 degrees of rotation between 0% and WOT of 100% so unlike a pot with 270 degrees of rotation they only have about 90 degrees rotation between 0 and full scale output.
The question is also what is the upper voltage limit for your A/D converter? You do not want to work with any voltage which exceeds the max A/D input. If something goes wrong, like an open ground for example, you can over voltage the OSD A/D. Also, I don't know what the A/D is, as in bit count? That will tell you how well it will resolve the incoming voltage and how much is enough.
Ron
by Jake Hertz
by Ikimi .O
by Jake Hertz