# convert voltage to Angle(degree)

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#### danjoro

##### New Member
my project is to convert voltage to angle(degree) using potentiometer. i already measure voltage and got their step in binary n hex..but my problem is how can i relate the voltage measured with angle(in degree)...??

#### zhaniko93

##### New Member
say you have maximum Vmax and minimum Vmin voltage and correspondingly angles Amax and Amin.
Calculate (Vmax - Vmin) / (Amax - Amin) = x and x will be Voltage for 1 unit of degree

#### danjoro

##### New Member
so i must use this formula to get voltage for 1 degree...i already measure the value for each degree in practical but the value not constant...what value should i get..using calculation o value measure in practical?...n can u explain to me about ASCII and BCD??

#### birdman0_o

##### Active Member
You must not be using a linear potentiometer!

Does it say type A or B on it?

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#### MikeMl

##### Well-Known Member
Most Helpful Member
As pointed out, you need to use a Precision, LINEAR potentiometer. Look at the linearity spec on any pot you are going to use.

#### ericgibbs

##### Well-Known Member
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so i must use this formula to get voltage for 1 degree...i already measure the value for each degree in practical but the value not constant...what value should i get..using calculation o value measure in practical?...n can u explain to me about ASCII and BCD??
You should be aware that general purpose potentiometers have only about 270 degrees of rotation, so you cannot use the Vmax thru Vmin divided by 360deg to give the angle/volt.
Measure exactly the total rotation the pot has in degrees and use that as the divisor.

#### danjoro

##### New Member
ooo..i think i use single turn potentiometer (5k ohm)...it's linear right...my potentiometer is about 300 degree...

#### birdman0_o

##### Active Member
from BCD to ASCII is simple: add hex 30 or decimal 48

#### danjoro

##### New Member
ok tq..it's ok if Vmax not equal with Vref?..fo example if Vref=5v and i get Vmax at 270 degree=4.18v....

#### birdman0_o

##### Active Member
How are you using the pot? Because thats wrong! Any resistance in series?

#### colin55

##### Well-Known Member
Use a table to convert the resistance (voltage) reading to degrees.

#### danjoro

##### New Member
the pot is in series with another resistor (1k)...in theoretical, voltage divider used to get the vout..the value is all most constant in practical..just some Volt can't be read...i just worry the inconstant value can effect my data o my final result...and it's the value vref=vmax??

#### MikeMl

##### Well-Known Member
Most Helpful Member
Why not apply VDD (the reference voltage for the AD converter)to the ccw terminal, ground the cw terminal, and take the output signal (AD input) from the wiper?

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#### birdman0_o

##### Active Member
What mike said is the way to do it. The way you have right now is not a linear function

#### danjoro

##### New Member
ok..i think i get it..then how to conversion to 8bit binary???...

#### MikeMl

##### Well-Known Member
Most Helpful Member
ok..i think i get it..then how to conversion to 8bit binary???...
Do you have a clue as to how to use the AD converter? If not, take a few hours and read 350+ page the Data Sheet.

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