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Old 03-03-2013, 07:44 PM
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tonybarry (Tony)
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Join Date: Aug 2007
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Quote:
Originally Posted by rcheshire View Post
A little more work with an L317 calculator, power dissipation 75mw at 3 amp and 25mw at 1 amp. This seems very low to me.

12v in 11.975v out R1 40kohm R2 132kohm.

Hi Rowland,

You need a minimum of about 2.5V drop across the LM317 to get it working. Otherwise it won't regulate. Vin = 15V, Vout = 12V is good. Again, check your currents and power dissipations.

The 317 is able to shut itself down if thermal excesses occur, but this is not a good idea unless you actually have a fault.

Regards,
Tony Barry
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