Patent ID: 6917689

Claim:
A sound mixing equipment, comprising an adjusting circuit having output terminals and input terminals; two buffers connected to the output terminals of the adjusting circuit at input terminals thereof; a first and a second voltage control amplifiers connected to output terminals of a respective one of the buffers at input terminals thereof; the first and the second voltage control amplifiers being connected to a left channel and a right channel of a first channel, and those of a second channel respectively at input terminals thereof; two amplifiers each connected to output terminals of one of the voltage control amplifiers at input terminals thereof; the adjusting circuit having reflecting plates joined to the manually operated control in opposite directions; the adjusting circuit having 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 being changed by means of moving the manually operated control, making the light transistors receive infrared rays emitted from corresponding light emitting diodes and reflected by the plates at adjusted distance to have desired amount of electrical currents due to the infrared rays so that proportion of sound signals of the corresponding channels to be mixed is adjusted.