KR790001631B1 - Transmitter-type touch-tone dial pulse generator - Google Patents

Abstract

The transmitter-type touch-tone dial pulse generator can be used in two ways for an impulse dial and a tone dial by means of installing a tone dial pulse generator at the transmitter of animpulse telephone. The actuating signal applied to the input of IC 1 is switched by the operation of transistors (Q1,Q2,Q3), and the output tone signal is lowpass filtered and amplified by transistors (Q4,Q5), and transmitted to the central station through diode(D1-D2) bridge circult.

Description

Transmitter Type Touch Tone Dial Generator

1 is a block diagram of a touch tone dial generator of the present invention.

2 is a circuit diagram of the present invention.

The present invention relates to a handset type tone dial generating device which makes it possible to use both an impulse dial and a tone dial by attaching the tone dial generating device to a transmitter of an impulse telephone currently in use.

Although the telephone subscriber call method uses impulse dial method and tone dial method, it is difficult to cope with the increase of the central station's rapidly increasing call volume when using impulse dial method. When the general consumer is inconvenient to replace the phone by the tone dial method, the economic burden has arisen.

The present invention has been invented in view of such a point, and the impulse dial telephones of the tone dial method can be installed by providing the apparatus of the present invention to the transmitter terminal of the telephone without changing the internal circuit of the conventional impulse dial telephones or modifying the appearance. It is economical because it can be easily used as a telephone and can be used as it is without replacing the telephone itself. Such a device can be used by attaching a soft touch dial plate on which a conductor is deposited on Mylar Film to the transmitter terminal. It is convenient to use, and unlike a carbon phone box of a general telephone, a small condenser microphone is built in, so that the sound is amplified by a transistor to provide a good call to the receiver. same. When one button is selected on the keyboard to generate a call signal for the exchange connection, a base current path is formed in the transistor corresponding to the selected _{one of} the switching transistors Q ₁ -Q ₃ to make the transistor conduction and connected to the collector. High-frequency frequency input terminals (8) (9) (10) of the IC and low-frequency frequency input terminals (2) (3) (5) (6) connected to the base circuit input logic " 1 " The circuit identifies the key selected from 0-9, *, # on the keyboard and divides the frequency from the main oscillator. In the high and low counting circuits, the frequency is counted and sent to the high and low DACs.

Each DAC circuit converts the input digital signal into an analog signal, and the changed high and low signal are mixed and a tone signal is output from the output terminal 7 of the IC, which is a resistor (R ₅ ) and a coupling capacitor. (C ₃₎ a via is supplied to the base of the transistor (Q ₄₎ was amplified by the transistor (Q ₄₎ the capacitor (C _2), was filtered in low-pass filter of the resistor (R _1), create a sinusoidal transistor (Q ₅₎ Amplify at and send the tone call signal through the bridge circuit to the central station via the transmitter terminal.

After the call, the voice signal converted by the condenser microphone is amplified by the condenser microphone through the condenser C ₃ to the transistor Q ₄ and Q ₅ through the bridge circuit. IC 1 is a tone dial generator that generates accurate tones with a frequency deviation of ± 0.25%, and transistors Q ₁ (Q ₂ ) and Q ₃ switch the pressed keys on the dial plate to IC 1 Transistor (Q ₄ ) (Q ₅ ) amplifies the tone signal output of IC 1 and the audio signal of condenser microphone and transmits it to the telephone line. The rectifier transfers the power supplied from the transmitter terminal to diode (D _1- ). The polarity of the power is unified with the bridge circuit of D ₄ ), and then a constant voltage source is made from the zener diode of the diode (D ₅ ) to make the operating power of each circuit and the operating power of the condenser microphone. The internal structure of IC 1 is as follows.

1) Key Board Logic

2) Higher Prescaler

3) Lower Prescaler

4) High Group D.A.C Circuit (High Group Digital To Analog Converter)

5) Low Group Digital To Analog Converter

6) Master Oscillator

Composed of the above, high and low frequency input pins are operated when Logic "1" or "High" state, and the signal frequency for exchange connection output from IC by input of keyboard is shown in Table 1.

[Table 1] Signal Frequency

As shown in Table 1, when one number plate is pressed, one signal selected from high and low frequency is synthesized, and a signal for exchange connection is sent. If two or more numbers are pressed on the dial plate, there is no output.

In this invention, the impulse phone can be used in combination with the impulse exchange method and the tone method by attaching the apparatus of the present invention to the transmitter terminal without modifying the internal circuit or the appearance, so there is no need to purchase a new tone dial type phone. It is an economical useful invention.

Claims (1)

As shown in the drawings and described in the text, the key pressed on the keyboard is switched to the transistors Q ₁ , Q ₂ , and Q ₃ to send a drive signal to the input terminal of IC 1. In mixing the low-group signals and outputting the tone signal from IC 1, the output tone signal is low-pass filtered by the capacitor (C ₂ ) and the resistor (R ₁ ) via the resistor (R ₅ ) and capacitor (C ₃ ). Q ₄ ) (Q ₅ ) to amplify by the diode (D ₁ -D ₄ ) bridge circuit to send the tone dial signal to the central station as a subscriber call signal to the transmitter terminal, and the audio signal of the condenser microphone is transmitted to the transistor (Q ₄₎ A tone-type tone dial generating device characterized in that the amplification by (Q ₅ ).

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