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Schematic of The Infrared Rays Wireless Headphone

2016-11-14 01:13  
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Schematic of The Infrared Rays Wireless Headphone
Because of the transmitter circuit of the inductive headphone must installed on the room wall or on the ceiling, so the inductive headphone can not be used outdoor, this is the main weak point of the inductive headphone. But the infrared rays wireless headphone is not in this case, for the flexible infrared rays transmitter circuit, it can be used in electronic teaching, home television and stereo equipment, audio wireless receiver, portable tape recorder, CD, VCD and MP3, makes the dream of wireless Walkman comes ture. Figure (a) shows the transmitter circuit of the infrared rays wireless headphones. To use it, you need to put the plug XP into TV's or tape recorders's headphones socket. The audio signal coupled by the capacitive Cl, enlarged by the transistor VTl, and transmited the audio wave infrared rays by the infrared emitting diodes VDl and VD2. After installation, you need to adjust the bias resistor R2 to make the quiescent current is l0mA. Figure (b) shows the receive circuit of the infrared rays wireless headphones. Infrared receiver VD3 ~ VD5 receive the infrared rays signal, converted it into audio signal, and enlarged by the transistor VT2 to bring in the integrated operational amplifier as power amplifier ICl, finally, the output signal exported by the headphone BE. To be able to receive signals all-round, there are three infrared rays receivers in the circuit. When testing, touch the positive electrode of the infrared rays receiver first, then adjust the resistor R4, R5 to make the Hum exported by the BE output largest, and then connect the transmitter circuit, adjusting the volume level of TV or radio cassette player, until the headset's outgoing volume become loud and clear.