My voltage constant varies, i need fixed rate to check against two bounderies programmaticly, if condition satisfy i'll supply my relay. If i set on my voltage supplier 10 v, ( let's say have two limits 10 > x < 14.4 in code) , it varies up and down.
In atatachments is scheme for how i connect resistors and other, and pictures from arduino monitor and instrument.
How to fix rate of voltage so i have steadily working relay?
On first picture i multipy with 0.0870233582, to get proper voltage.
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html
then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks... Tom.... 
But what kind of voltage do you try to measure? Where does it come from?
If I have understood correctly, you have some circuit / device that generates 10V with tolerance of +- 4V. ( which is very dramatic.) and you need to have your relay on when the value is between the range.
What you need is generally call Hysteresis.
First off all DO NOT DIRECTLY SUPPLY MORE THAN 5V TO ARDUINO I/O. Only one thing you can have guaranty then is firing your I/O pin or worst case a IO port.
At Arduino implementing Hysteresis by software is a bit expensive thing as you are utilizing much of your processor just to continuously observe the input/s, even if it is well settled in your range.
Are you aware of opAmps can do this for you. Have a look at this document. It will be very beneficial if you implement hardware Hysteresis and give its output to one of interrupt on Arduino. Then you and put all your other code in the interrupt routine.
hope it will be useful to you.
Hi,
It sounds like English is not your first language, can you tell us what your language is please?
Thanks.. Tom....
