Phone Speech Signal Wireless Transmitter ----- Telephone Transmitter

Telephone speech signal wireless transmitter, Telephone Transmitter Keywords: phone speech signal wireless transmitter The telephone wireless generator circuit is simple and practical, and the two parties can be transmitted to the air, and can be received by the wireless receiver. The principle shown in the drawings. The transmitter consists of two parts consisting of the automatic switch and FM transmitter. The automatic switching portion is composed of R1 to R3, the fine tuning potentiometer VR1, the transistors T1, T2, the regulator tube D2, and the diode D1. R1 and VR1 form a voltage divider, when the DC voltage of the telephone line is 48V, the output voltage VR1 of 0 ~ 32V. The conversion of the working state of the circuit depends on the breakdown voltage of the regulator D2 (here 24V) and the on-voltage (0.7V) of T1, so the output of VR1 is adjusted to 24.7V, the D2 breakdown and T1 is turned on, at which time T1 is lowered, T2 is turned off. If the telephone to pick up the handle, the telephone line voltage drops to about 11V, T1 is turned off, T2 is turned on, T3 DC path is formed, the start-up circuit. The small power frequency frequency frequency transmitter consists of a transistor T3, a coil L1, and the like, and the T2 functions as an electronic switch (on / off), the audio signal on the telephone line is modulated to the oscillation frequency, modulate the oscillation frequency, modulated along the transistor T2 and the series resistance R3. after the high-frequency signal to the antenna. As long as the FM receiver tunes to the transmit frequency of the FM transmitter, the call can be heard. The L1 is lacquered with the SWG36 in the electrical resistance of 1 MΩ, 1 W around 45, L2 is a hollow coil having a diameter of 12 mm, and the swag 3 is covered with the SWG21. The DC power supply of the circuit takes a self-telephone line without an external power supply, and since the circuit consumes small power, it does not affect the normal operation of the phone. The transmitter After debugging, the cartridge can be installed in 5cm 3.75 ×.

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