filament current การใช้

Now, temperatures and their corresponding pyrometer filament currents are known and a curve of temperature versus current can be drawn.
Little practical use was ever made of this property ( however early radios often implemented volume controls through varying the filament current of amplifying tubes ).
Additionally the pre-amp uses four 12AX7 tubes simply because it has enough filament current to afford an extra so the V1 can be paralleled.
The rheostat " "'R " 1 "'controlled the filament current, and in these early sets was used as a volume control.
The user then reads the temperature off the filament current control dial, which is calibrated by the filament's current-vs-temperature curve . or in some instruments from a current-vs-temperature table.