OPTs on the cheap ?
Posted: Wed Sep 26, 2007 6:26 amI just read a note about this, over at the Magnequest forum, but I have read about this a long time ago, though I never actually tried it. I wouldn't expect true "golden ear" sound quality, but for a qick "try-out" for prototyping, it might just work.... IIRC, someone used this in conjunction with a 6EM7 (or similar) lo power SET design, and claimed good results.
Using a filament trannie as an OPT: for example, a 120V to 6.3 VAC trannie would act as a 3K primary with an 8 ohm load. (roughly 400:1 impedance ratio for a roughly 20:1 turns ratio). Actually, around 362.6 :1 works out for 120V:6.3V, so 2900 ohms is the more "precise" figure, but then this isn't exactly brain surgery Yellow_Light_Colorz_PDT_06 Yellow_Light_Colorz_PDT_08
Granted, it doesn't have the normal air-gap that an SE OPT should have, but if the current through the winding is kept at a reasonable level, core saturation shouldn't be an issue.
Any thoughts, rotten tomatoes, etc ? Yellow_Light_Colorz_PDT_09 :o
Yellow_Light_Colorz_PDT_11 Yellow_Light_Colorz_PDT_07
/ed B in NH
Using a filament trannie as an OPT: for example, a 120V to 6.3 VAC trannie would act as a 3K primary with an 8 ohm load. (roughly 400:1 impedance ratio for a roughly 20:1 turns ratio). Actually, around 362.6 :1 works out for 120V:6.3V, so 2900 ohms is the more "precise" figure, but then this isn't exactly brain surgery Yellow_Light_Colorz_PDT_06 Yellow_Light_Colorz_PDT_08
Granted, it doesn't have the normal air-gap that an SE OPT should have, but if the current through the winding is kept at a reasonable level, core saturation shouldn't be an issue.
Any thoughts, rotten tomatoes, etc ? Yellow_Light_Colorz_PDT_09 :o
Yellow_Light_Colorz_PDT_11 Yellow_Light_Colorz_PDT_07
/ed B in NH