Regulated DC heater supply

[Vincent77]

There is no connection of V- to PE/outside cover?

BTW it is not the LM2596 you mentioned and of which I asked if you had measured it, that was this one:

Indeed, no connection between V- and PE/cover.

I evaluated the LM2596 too as indirect heating regulator (a good 10 years ago) and found no bad influence or sound change compared to a LM317, but I don't have one now to re-measure.

 

[jean-paul]

Measurements would be better than judging by ears. As stated before I have had no single occurrence still now where LM2596 circuits were not radiating garbage.

This 6.3V metal box SMPS is an exception. Many have V- connected to casing/shield and thus PE and this a direct short circuit of anything connected to V- to PE. "Lifting" a filament voltage would then not work.

 

[Magz]

7.8V was under load. The load current is nominally 2V so LT1764 would be OK I imagine. It works fine with LM338 and no doubt better with LT1084. In what way is LT1084 preferable to LM1084?

LM1084 is from Texas Instruments. Equivalent to LT.