Neils,

Many of these switching regulators have a 50 KHz switching frequency. This has images inside the passband of the audio codec.

I arrived at LM338 only after experimenting with various switching systems (including building one from discrete components). These new generation of switchers move the frequency to 500 KHz. That's what makes them useful.

- f

On Wed, Aug 10, 2022, 6:27 PM John Terrell <N6LN@...> wrote:

The smallest ones have a small cheap potentiometer which I would not trust in the long run to maintain a stable output voltage. Some have a secondary means of choosing between four or five fixed voltage levels and bypassing the fickle potentiometer by cutting a pcb trace with a hobby knife. Loupes help. But in any case a buffer capacitor ought to reduce a noisy output p.