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What am i doing wrong?

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shipto:
Working on a project that requires a dual voltage power supply 24v and 5v my electronics skills are limited to following other peoples circuits and this one is me combining 2 seperate circuits.
Please excuse the crude drawing but I have included it to show the way I am attempting to accomplish this.
The lm338k is a 5 amp power regulator which is supplying the 24v line and this is working fine however the lm317t which is intended to take that 24v down to 5v is the problem no matter what i do I cant seem to get it to work I am getting 24v on the 5v line.
I have searched and cant seem to find the answer but I am sure it should work and can only assume I am missing something.
Thanks for any help

John Rudd:
Firstly have you got the 317 connected the right way round?
What value resistor have you got from the o/p to the adj pin?

Your cct should look like this:

andreas:
You can check for bad potentiometer on the adjust pin or in the worst situation replace the lm317 as a test.
Check this also for more info. http://www.ti.com/lit/ds/symlink/lm317.pdf

DMIOM:
First quick thoughts, and please forgive if these are things you've already checked/considered:

1/ Pinout - are you absolutely sure the device is wired right? (I know I've blown, or at least shut-down, regulators before when prototyping)

2/ Is the LM317T getting hot - that's a lot of voltage for a linear device to be dropping? - it may be in thermal shutdown, and since it doesn't have a ground terminal, I'm not sure what'll you see if it can't cope.

3/ What values have you got for the output-to-adjust feedback resistor and the pot? and is it a lin or log pot?

4/ Is there any real reason to use an adjustable regulator? - a linear 7805 variant reg would be dissipating vast heat, but  I make extensive use now of switching regulators such as Recom R-78C5.0 - they can run off up to about 40v input, but because they're switching devices, their efficiency is much much higher & they don't heat-up anything like so much

Dave

Edit: oops - too sloooooow a typist! - cross-posted same time as John & Andreas

shipto:
Actually I just noticed the potentiometer on the 317 is wrong I actually have two resisters r1= 270ohm r2=820ohm following the below chart which should result in 5.05v. I am very sure I have it all wired the right way around but I will try it all again just in case. As no one has (yet) said theres no way it will work I am guessing it has to be a wiring problem, which I wont rule out.

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