| 摘要 |
In a sound mixing equipment, an adjusting circuit has reflecting plates joined to a control in opposite directions. The adjusting circuit has a first light emitting diode and a first light transistor disposed to face one of the reflecting plates, and a second light emitting diode and a second light transistor disposed to face other one of the reflecting plates. Distance from the light emitting diodes to the corresponding reflecting plates is changed by means of shifting the control, making the light transistors receive infrared rays reflected by the plates at adjusted distance to have desired amount of electrical currents. Channels and output terminals of the light transistors are connected to input terminals of sound mixing mechanism. Thus, proportion of sound signals of the channels to be mixed is adjusted.
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