TV Residents Infrared Transponder ----- Audio Transmitter

Keywords: TV sound infrared forward repeater The repeater consists of two parts that transmit and receive. Figure 1 (a) is the principle of transmitting partial circuits. The sound (audio) signal after the verifier is confirmed by the triode VT to promote the infrared transmit tube. Since the emission intensity of the emission tube is proportional to the current thereof, the infrared light emitted by VD1, VD2 is adjusted by the audio signal. In order to prevent distortion, VD1, VD2 to set a certain bias. This TV sound infrared repeater has the advantages of simple structure, easy to make, no interference, low noise. Working principle The repeater consists of two parts of the transmitting and reception. Figure 1 (a) is the principle of transmitting partial circuits. The sound (audio) signal after the verifier is confirmed by the triode VT to promote the infrared transmit tube. Since the emission intensity of the emission tube is proportional to the current thereof, the infrared light emitted by VD1, VD2 is adjusted by the audio signal. To prevent distortion, VD1, VD2 to set up a certain bias. Fig. 1 (b) is a schematic part of the receiving part. Its circuit uses an audio amplification integrated circuit LM386. VD is the infrared receiver. When the infrared light modulated by the audio signal is irradiated to the VD, the same electrical signals as the audio signal change law is generated at both ends, and is enlarged by C1 to IC. Since the IC has power amplification, 1-4 secondary headphones can be listened. Component selection and production triode VT selected 8050 in power tube, PCM = 300mW, ICM = 500mA, R2 power is not less than 1/4W, VD is an infrared receiving tube (cannot be used as a photodiode, otherwise it affects the visible optical interference). The debugging of this transceiver is very simple. The transmitting portion only needs to adjust R1 to cause the VT's quiescent current to 30 mA. The receiving section is not required to be debugged as long as it is installed. The transmit portion can be mounted inside the TV, and power is powered by 12V in the machine. Signal input A, B end, receives both ends of the volume potentiometer. For a telephone that is controlled by the DC volume of the integrated circuit, A and B can be connected to both ends of the speaker, but to add a switch to turn the speaker (more convenient to use the headphone output jack). Adjust the volume so that it is forwarding the distance and does not distortion. At the time of installation of the two launch tubes, consider its radiation range, allowing their effective radiation angles to overlap. The sensitivity of the transponder is designed to lower the aim to increase interference. It is measured, and its effective forwarding distance is not less than 3m, which can fully meet the needs of the general family.

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