During one of the first public demonstrations of the "Bell Solar Battery" the device powered a small radio transmitter, carrying both speech and music.
最初的公开示范之一便是将一台小型无线电发射器装上“贝尔太阳能电池”，传送讲话与音乐。
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Then, after a 12-day gap in 1876—when Bell went to Washington to sort out patent questions about his work—he suddenly began trying another kind of voice transmitter.