From: jl@glen--canyon.com   
      
   On Wed, 24 Dec 2025 00:23:54 -0000 (UTC), Phil Hobbs   
    wrote:   
      
   >Lasse Langwadt  wrote:   
   >> On 12/23/25 20:33, john larkin wrote:   
   >>   
   >>>   
   >>> 317/1117 regs don't like ceramic loads.   
   >>>   
   >>   
   >> the 317 should be much more stable, they must be quite different, the   
   >> 317 is twice the dropout of the 1117   
   >   
   >Different vendors’ parts have different stability properties, and it   
   >depends on the output voltage.   Twenty microfarads with 5 m? ESR can   
   >easily make a 317 sing.   
   >   
   >JL’s trick is to put 10nF across the top resistor, which gives enough phase   
   >lead to stabilize the loop even with big ceramic caps.   
      
   That won't work when I want 1.2 volts out!   
      
   >   
   >Another good approach is to use a huge wet-Al output cap as a lead-lag   
   >network.   
   >   
   >Cheers   
   >   
   >Phil Hobbs   
      
   A tantalum output cap works too, 33 uF or some such; the ESR is about   
   right, even with a mess of ceramics downstream. Just derate 2x or 3x   
   on voltage so it won't detonate.   
      
      
   John Larkin   
   Highland Tech Glen Canyon Design Center   
   Lunatic Fringe Electronics   
      
   --- SoupGate-Win32 v1.05   
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