Depends what specific chokes they are. Small ones generally have too high DCR - if you have space go for the bigger ones.
the bigger chokes have 2.5R DCR, Epcos ones about the same. These are the ones Ray uses in his CD mods. He also uses 1mH chokes with much higher resistance (14-25R) for Opamps. I don't know why but I feel I should follow his example so I don't screw up.
2.5ohms isn't too bad but still around 10X greater than ones I've used. I'd not want to use 14ohm chokes on supply lines.
The original supply resistors on my Philips CD players' opamps are 33ohm. I assume they used that value for a reason while using much lower values for other ICs. Ray advises to use chokes with a DCR about half the original resistor value.
From my experience, LM3xx regulators are not at all that sensitive to ESR of output caps. In several dozens of overhauled CD players and preamp sections, I have never had any problems with low ESR (not ultra-low ESR, though) after LM regulators.
Read this paper, page 13 illustrates how to make an LM317 with insufficient phase margin when a tantalum is used instead of aluminum electrolytic:
http://www.omicron-lab.com/fileadmi...notes/App_Note_Noninvasive_Stability_V1_2.pdf
I do not doubt, however here we are talking about LM317 in an existing application, rather than considering a project.
- Status
- Not open for further replies.