-------------------------------------------------- From: "RussellMc" Sent: Wednesday, August 04, 2010 12:56 AM To: "Microcontroller discussion list - Public." Subject: Re: [EE]LM317 regulator output voltage fluctuation >> Have you tried it with the LM317 output disconnected from the rest of th= e >> circuit to help locate where the problem actually lies? > > Just for interest and to possibly help others avoid spending an > interesting time: > > Disconnecting the load as above MAY cause bad circuit operation, > depending on what design decisions were made originally (or not). Good point - I should have mentioned using a dummy load instead, especially= =20 since my next question was whether the correct loading was being applied :-= ) The main reason for that point was as you say, I thought it unlikely the=20 LM317 was "humming", so removing the (unknown) ICs attached would help=20 locate/simplify the problem. Also as mentioned, there is no getting away from reading datasheets=20 thoroughly, spending a few minutes doing so can save hours of problems.=20 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .