據說直流燈絲會讓陰極提早中毒身亡
聽說的聽說的聽說的
原因類似sputtering

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據說直流燈絲會讓陰極提早中毒身亡
聽說的聽說的聽說的
原因類似sputtering ...
xiao 發表於 2019-11-4 11:13


我都聽過。有D人會用ac supply,但在燈絲兩端加電阻再落地嚟減少hum聲

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我都聽過。有D人會用ac supply,但在燈絲兩端加電阻再落地嚟減少hum聲
vtrchan 發表於 2019-11-4 21:00

冇錯。將6. 3V劏開做±3.15V

via HKEPC IR Pro 3.6.1 - Android(3.3.1)

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聽聞用直流,斷灯絲機會會大D
見以前啲美國古董機好少會用DC灯絲,
一樣咁靜,應該有佢原因,最緊要落地做得好

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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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