Very well explained sir. Thanks a million! OH WAIT !! what about cap size??

yeah I appreciate it though , one more  question

   24 / 5 = 4.8.   Use a 56k/10k resistor to get a 5.6 divider

what does the 4.8 mean ?  and how did you find those values so fast? i usually have to look at how much my input is, say 24v and then how much output i want say 6volts and then figure out what percentage 6volts is of 24volts , which is  25% then i know one of my resistors has to be 25% of R1 + R2 .... hehe probably over complicating that as well :/

interesting what having the know how can do for an individual Kudos to you! because now that you mention it connecting both LMs to the same pot would cause major hiccups, because that WAS what i was thinking. Now back to the drawing board, on how to make a digital variable power supply...

well i can actually still do it right? just use the good old fashion divider method and some math on the software side and all is well?

I was just thinking ONE adjustable divider being adjusted at the same time as the main voltage i am trying to adjust was better then dividing the voltage with resistors, then having to worry about power dissipation  for the resistors , meaning  i would have to go buy some , at least, 1 watt resistors and then also not being able to find the exact resistor value i need etc...
either way perhaps some insight on choosing caps?


i spelled "chossing" terrible.

well as i vary the 24v via a pot i would also vary the "adjust" pin on the LM317 ... thus lowering its output in proportion to the 24 so when the i have 24v the LM317 will be at 5 and as i drop 24v ill also be dropping the LM317 ....forgot to mention it is an adjustable regulator

ok so my power supply remains in my head still but  i have purchased some parts , but I have  decided to make it a 24v  variable supply , my question now is
about making the reference voltage so i can read it with an Arduinos Analog input , i was thinking of a voltage divider where  i drop the 24v to 5v  for the arduino to read and when i drop the 24volts the 5volts would  also drop in proportion which is how i intend to display the "real" output of the power supple..  
question is instead of a voltage divider, resistor method which is what i was thinking , can i just use an LM317 with fixed resistors to get a good solid 5v for the arduino and still have it drop accordingly to my 24volts dropping?
hope i am making my self clear :/ ,
furthermore what size caps should i use? Though i'd prefer to know the method of choosing the right size caps as oppose to a specific value , you know the whole teach a man how to fish thing....

 thanks in advance.

ps: i would also be using ANOTHER LM317 to actually vary the 24v

LM317 DS : http://www.mouser.com/search/ProductDetail.aspx?R=LM317Tvirtualkey51120000virtualkey511-LM317T

ive read a lot of posts about 022 and windows 7  64bit... im on a windows 7 ,  64bit,  AMD , java version 6 update 6..
arduino build 022 ,  driver version 5.1.2600.0  and has worked fine since day uno , maybe you can try to match those settings, also i update my windows everytime there is an update available,

Please do not focus to the code but to what causes problems to my program when i enter the command.

well making one variable = another variable of the same type  is not a problem that means the problem is in your code, so how are we not suppose to look at the code as a whole?

Code:

if(key=='*')
          {
              Serial.println("DTMF Reset...Waiting for delay."); memset(mypinakas, 0, sizeof(mypinakas));  [glow=yellow,2,300]index=0;[/glow]
          }
          
          if(key=='#')
          {
            
             m_x=mypinakas[0];
             m_y=mypinakas[1];
             dtmfdelay = m_x*10+m_y;
              Serial.print("Thermosifwnas ON for: ");
              Serial.print(dtmfdelay);
              Serial.println(" minutes.");
          
              memset(mypinakas, 0, sizeof(mypinakas));
              //Serial.print(mypinakas[0]); Serial.print(mypinakas[1]);Serial.print(mypinakas[2]);Serial.println(mypinakas[3]);
              [glow=yellow,2,300]index=0;[/glow]
          }

and then

Code:

[glow=yellow,2,300]if(index < 5)[/glow] // One less than the size of the array
           {
               mypinakas[index-1] = dtmf_digit; // Store it
           }

it is always going to be less then 5 because you either set it less then 5 or you never let it get passed and then you SET it to 0 and then subtract 1 ? 0 -1 ?,  Also index < 5 is NOT ONE less then the array it is EVERYTHING less then 5 which means 4 and below and the array is 6

where is "read_codigo();" that might help resolve the issue if we could see the code

and with the code you have shown here you never even look at key_previous or compare it to anything..soooo whats its purpose?
perhaps your ENTIRE code might help.

there is an Arduino plugin for visual c++ with auto complete and all the other features visual studio offers however it is only works with The professional version, meaning if you have the free express version of VS it will not work.

can you post the error message

This is an arduino project that was made to help/improve a handicap child's life.

http://arduino.cc/blog/2011/10/05/arduino-ipod-and-rfid-make-beautiful-handicapped-accessible-music-together/

http://www.st.com/internet/evalboard/product/252419.jsp?WT.ac=p2_bn_sep11_stm32f4discovery

just in case anyone is interested i have no idea what to do with it but i got mine in the mail today, free

OK so i am making a small variable power supply , 12v max , to use with my breadboards.
as well as an LCD (16 X 2 characters) to display how much voltage  i am using at the moment.

i know i can only use my A.inputs with a max of 5v and translate the reading into voltage

Code:

 int  temp ;
  float val ;
  temp = analogRead(5);
  val =(float)temp * .0049 ;
 

But my power supply is going to be 12v not 5v , so with some research i figured i could make a voltage divider  where i  have a max of 12v i will get a 5v output to use on my analog input reading, now  being that this 5v will be an equivalent to the 12v how do i convert my 5v reading up to 12v?

i am assuming it is not as simple as mapping my reading AFTER the conversion i posted above..map (newTemp, 0 ,5 , 0 , 12)  ?