Life is always more interesting with a little mystery.

 

Life is always more interesting with a little mystery.

I agree with you on that but note that I am using the old Chinese definition of "Interesting", which has a unique connotation.
Also, consider that the explanation of the reason for fear is believing that one is unable to handle what is, or would be, happening. And not knowing is often a reason for not being able to handle a situation. Thus I much prefer to know what I am getting into so that I can handle it. (additional explanation deleted.)

 

This is the challenge from my electronic class That how to make a dual supply from single supply which can provide voltage from 3 V to 10 V and when connect to the load (?? ohm) which current is 300 mA the voltage must not DROP ( Regulated )
and this is My latest work

Before connect to the load and after connect to the load The Voltage was not Drop and the reason why ?
I think because the DROPOUT VOLTAGE in the Regulator LM317 ( There is no data about dropout voltage in Datasheet ) so I think that the dropout voltage might be like +2.5~3 V and Look like it's right but in LM337 after increase the V input to ( V out + 3 V) the voltage is drop and after incresing more V input finally at 28 V the LM337 is regulate Voltage not drop. I am not sure that am I right??

Anybody know how can I find the data about DROPOUT VOLTAGE of the Regulator ( LM317 / LM337)

 

Oh another question? Why the Voltage from LM337 is less than Voltage from LM317

 

Hello,

You can find the dropout voltage in the datasheets.
Alldatasheet has datasheets from the different manufacturers:
http://www.alldatasheet.com/view.jsp?Searchword=LM317
http://www.alldatasheet.com/view.jsp?Searchword=LM337

Bertus