KR920008231B1 - Beat signal automatic removing circuit - Google Patents

Abstract

The b signal removing circuit for automatically removing the harmonic components of the high freq. signal generated upon recording the broadcasting signals of tuner into a tape to reproduce the clear-cut tape sounds comprises a muting means for interrupting the inputting of the broadcasting signals to a recording head (18) in a constant time when a recording switch is operated, a square wave generating means for detecting the beat sound signals from the tuner to rectify the detected signals to convert the detected signals to square waves, a control signal generating means for receiving the square wave signals to generate control signals, and a beat sound removing means operated by the control signals to remove the beat sound applied to the recording head.

Description

Bit signal automatic elimination circuit

The accompanying drawings are bit signal automatic removal circuit diagrams of the present invention.

* Explanation of symbols for main parts of the drawings

1, 13: AND gate 2: recording leaf switch]

3: Shift register 7, 15, 20: Switching transistor

11: comparator 18: recording head

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic apparatus, and in particular, to automatically reproduce harmonic components (eg, beeping sound components) of the harmonic signals generated when recording a broadcast signal by a tuner to a tape, thereby reproducing a clear tape sound during playback. The present invention relates to a beat signal automatic elimination circuit.

When recording a broadcast signal by a tuner in an audio device such as a tape recorder, a bit signal is often generated between harmonic components of the recording bias frequency and the tuner reception frequency. So in order to remove this, almost all sound equipment is equipped with a beat-removal switch, but most beat-removing switches are normally attached to the rear of the device, so when a bit is generated while a set is installed, the switch is operated. If you press the record button to record a very important music while you are listening to the broadcast, when the beat sound occurs, the first part of the recording is already sounding because a considerable time has already passed when the switch is operated to remove it. There was a faulty recording condition because it was recorded without being removed.

Accordingly, the present invention has been made in view of the above circumstances, and the electronic drive is performed at the same time as pressing the recording button to improve the performance and quality of the product by maximally reducing the recording without the drive bit is removed in a very short time The purpose is to provide a bit signal automatic control circuit.

According to an aspect of the present invention, there is provided a radio apparatus for receiving a radio broadcast tuner and a recording circuit, comprising: a muting unit for blocking a broadcast signal from flowing into a recording head during a predetermined time when the recording switch is operated; A square wave generator for detecting a beat sound signal output from the output of the radio, rectifying it into a half wave and converting it into a square wave, a control signal generator for generating a predetermined control signal when a recording switch is pressed using the square wave as an input; And a beat sound removing unit for automatically removing the beat sound applied to the recording head by operating according to the control signal.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 shows a bit signal automatic removal circuit diagram of the present invention. First, while the radio is being listened to, the power supply B ⁺ of the tuner is applied to one input terminal of the AND gate 1. Therefore, when recording is to be performed in this state, the recording leaf switch 2 is turned on as the user presses a recording switch (not shown). At this time, a high state signal is applied to the remaining input terminals of the AND gate 1, and the output of the AND gate 1 becomes a high state, and this signal is applied to the clear terminal CLR of the shift register 3, thereby shifting the shift register. (3) enters the operating state by external conditions.

On the other hand, when the recording leaf switch 2 is attached, the instant arc is detected and charged through the capacitor 4 and rectified by the diodes 5 and 6 to be applied to the base of the transistor 7. do. At this time, since the transistor 7 is turned on, the broadcast signal through the antenna 8 is not applied to the tuner input terminal. Therefore, the broadcast signal is interrupted in the recording head during the time constant period t _{1 =} C ₄ × R ₉ by the condenser 4 and the resistor 9.

If the recording leaf switch (2) is pressed to record AM, no signal is output during the time by the capacitor (4) and the resistor (9), and only the noise signal is output from the audio output. When generated, a sine wave is generated at the audio output.

This sinusoidal wave is rectified into a half wave while passing through the diode 10, and is applied to a comparator 11 which is a circuit that turns the half wave into a square wave. The square wave produced by the comparator 11 is input to the clock terminal CLK of the shift register 3 through the resistor 12.

In this case, since the high state signal (+ Vcc) is always applied to the input of the shift register 3, the shift register 3 has its outputs Q ₁ , Q ₂ , and Q ₃ whenever the clock pulse CLK enters. ) Is shifted one by one as ＂H＂. If the bit waveform is generated and the clock pulse of the square wave is input and the outputs Q ₀ , Q ₁ , and Q ₂ of the shift register 3 are all high, the NAND gate 13 generates a signal in a high state. And the transistor 15 is turned on by applying the resistor 14 to the base of the transistor 15. When the transistor 15 is turned on, one of the capacitors 16 is grounded to form a capacitance (C ₁₆ // C ₁₇ ) and the bias frequency is changed. The generated bit point disappears as the bias oscillator frequency changes. That is, no beat sound is recorded in the recording head 18 at all.

In addition, the output of the AND gate 13 is input to the base of the transistor 20 through the resistor 17 to turn on the transistor 20 so that the power supply of the square wave comparator 11 is cut off. Therefore, the square wave does not occur and the comparator 11 does not operate even when the sinusoidal wave enters through the diode 10 in the normal operation after the bit removing circuit is operated. This can prevent malfunction of operating the transistor 15. That is, malfunction can be prevented by the voice frequency.

점에는 구평파가 나타나지 않게 되어 시프트레지스터(3)의 클럭 펄스단자(CLK)에 구형파가 입력되지 않아 시프트레지스터(3)의 출력레벨(Q₀, Q₁, Q₂)이 그대로하이상태를 유지하여 앤드게이트(13)의 출력이 ＂H＂로서

점이 변하지 않는한 트랜지스터(15)를 계속적으로 턴온시키게 되어 비트 제거동작은 녹음 동작을 해제하지 않는 이상 계속 유지된다.Also, because the comparator 11 does not work

Since the square wave does not appear at the point and no square wave is input to the clock pulse terminal CLK of the shift register 3, the output levels Q ₀ , Q ₁ and Q ₂ of the shift register 3 remain high. The output of the AND gate 13 is

As long as the point does not change, the transistor 15 is turned on continuously so that the bit removal operation is maintained unless the recording operation is released.

On the other hand, when the recording is finished and the stop button of the deck (not shown) is pressed, the recording leaf switch 2 is turned off, and one input terminal of the AND gate 2 is turned to L, and the output of the AND gate 2 is low. Becomes At this time, since the low signal is applied to the clear terminal CLK of the shift register 3, the shift register 3 is reset and enters the initial state.

In addition, since the output of the AND gate 1 becomes low during the recording operation in the non-tuner state, the bit removing circuit does not operate.

The present invention operates as described above, when a bit is generated in the tuner recording, it is made into a square wave and used as a clock signal of a shift register, and a controllable signal is made therein to drive a bit removing driving transistor so that the sound is not made by human hands. By removing it, it has the characteristics to improve convenience and product performance and quality.

Claims (1)

A bit signal removal circuit of an acoustic apparatus having a tuner for receiving a radio broadcast and a recording unit; The capacitor 4, the resistor 9, the double voltage detection diodes 5 and 6 to block the broadcast signal from entering the recording head 18 during the initial operation of the recording leaf switch 2 for a predetermined time. A muting unit comprising a transistor (7) operating by a double voltage detected signal to block a broadcast signal; and a diode (10) for detecting a beat sound signal output from an audio output terminal of a radio and converting the detected signal into a square wave. A square wave generator comprising a comparator 11 for the same; A control signal generator comprising a shift register (2) and an end gate (13) for generating predetermined control signals (Q _O , Q ₁ , Q ₂ ) when the recording switch (2) is pressed with the above-mentioned square wave as input; ; And a bit tone removing transistor (15) for automatically removing the beat sound applied to the recording head (18) by operating according to the control signal described above.

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