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6.3V燈絲用整流二極管應選用較低Vf類如4A或以上60V肖特基二極管Schottky Diode,就唔使太擔心二極管過熱問題。MUR820係適合較高頻高壓,火牛6.3Vac供應燈絲係市電頻率50Hz,唔使用到MUR820快速復元(但較高Vf)二極管,想平價D唔用肖特基二極管的話可用一般用途6A 50V整流二極管都得。不過整流後一般要接較大電容(4700uF或以上 10V ),有機會令輸出直流電壓較唔穩定,可參考以下資料
http://bbs.hifidiy.net/forum.php ... page=1&mobile=2

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本帖最後由 diputs 於 2019-11-8 10:48 編輯

直流電較快燒断燈絲係由於所謂filament notching效果,而這種效果只適用於很幼的燈絲(0.001吋/0.025mm直徑或以下),網上有資料如下:
http://amfone.net/Amforum/index.php?topic=9060.5;wap2

Filament notching is only a problem with filament wires around 0.001" diameter or less.  Tubes that the audiophools would use are not in this boat, unless they have fallen in love with 1R5's now - a 50 milliampere filament.

I don't have a table of tube and pilot bulb filament diameters, but I would guess that a filament greater than about 100 milliamperes is out of range of the problem.  Perhaps someone else has access to tube or bulb filament mechanical specifications.

12AU7, 12AX7   150 milliamperes
6SN7    600 milliamperes
6F5    300 milliamperes
6A3, 6B4  1 ampere
300B   1.2 amperes
45      1.5 amperes
805    3.25 amperes
810    4.5 amperes
811, 812  4.0 amperes

過高電壓及剛開着時的浪湧電流對燈絲壽命影響更大,想增長它的平均壽命,可以稍降低電壓及限制過高的浪湧電流方向入手。
Formula for Incandescent Lamps
(Actual Life/Rated Life) = (Rated Volts/Actual Volts)^13.
即如供電壓從6.3V降至5.8V,壽命可比標稱增長約2.9倍
限制浪湧電流可在直流輸出加入適當電感線圈、電子限流、低壓起動等。

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