The production of several wireless headset and trial experience

Are on their production and use of several wireless headset experience description for your reference.
First, as shown in Figure 1, the program produced by FM wireless transmitter, including machine, including the total LED current of only 5 mA, using either a FM radio within 20 meters and stability to receive, and separated from the wall effects. Transistor emitter resistance can be adjusted to improve the modulation distortion, adjust the tuning capacitor to the transmitter signal emitted within 87 ~ 108MHz, while avoiding the local FM station and does not interfere with TV programs can be. Signal source with a lotus plug from the TV or DVD, VCD audio output hole out. The beginning of the headset with ordinary hand tune AM / FM radio to listen to good effect. Sony SRF-MH22 after the switch to adjust the number of deposit stereo headset to listen to radio, very easy to use, sound quality greatly improved, there is no background noise.
Program one can not listen to stereo signals and, based on "electronic newspaper" description produced with BA1404 FM stereo transmitter, 1.5V power supply when the machine is in use only 4 mA total current in the range of 10 meters can be stable reception. Just press the regular production line Mapping, Continuous replacement of four BA1404 still does not work. After careful analysis of the line, because without power amplification stage, to estimate the RF oscillator circuit is ⑨ foot 15pF capacitor to ground short circuit, disconnect the capacitor to work until after the circuit shown in Figure 2, this time in the making should be addressed. Receiver is still using the Sony SRF-MH22 receiver, single-channel effect is obvious, sound quality is also good. However, receiving a stereo signal (ie, stereo receiver decoder open work) when significant background noise, I do not know is due to the 19kHz pilot signal transmitter caused by, or issued by the receiver decoder. Meanwhile, the machine is not completely separate stereo signal, using the general effect.
Receiving a high quality stereo audio, and my purchase of a Blue House brand headphones infrared wireless stereo headphones. After analysis, the aircraft with the 7th year of "e-paper" describes the IR900 infrared stereo headphone structure similar to the left and right channel transmitter with a signal modulated on the CD4046 were fired by two-way infrared diode, so the receiver channel by the infrared receiver, transistor amplifier, frequency selection through the patch after the demodulation block and A007B enlarge and promote the headset, the headset speaker diameter of 25 mm. The audition, its very good stereo separation, voice clarity, good sound quality. Less than the machine to use two on the 7th battery, battery consumption too fast.
The after use that to receive a single channel signal if the main program of Figure 1 can be used to satisfy requirements. If the main stereo signal receiver, infrared wireless stereo system should be used to listen to, and FM stereo signal to noise ratio due to poor stereo separation is not high enough, it is best not to use, of course, use two single-channel FM transmitters firing left and right channels signals, and then received two FM receivers were also a good way.


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