KR910004720Y1 - Audio dubbing circuit using transistor - Google Patents

Abstract

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Description

Voice Dubbing Circuit Using Transistor

1 is a block diagram of the present invention.

2 is a detailed circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

10: buffer control unit 20: buffer unit

30: high frequency elimination part R _1- R ₉ : resistance

C ₁ -C ₃ : Capacitor Q ₁ -Q ₅ : Transistor

L ₁ : coil

The present invention relates to a voice dubbing circuit using a transistor in a video system.

In the past, since the voice dubbing function of the video system was controlled by a mechanical switch of the relay, the reliability of relay operation was lowered and the cost of components of the relay was expensive under adverse conditions such as high temperature and high humidity. In addition, there is a problem that the video signal that is already recorded is deleted during the recording operation because the high frequency component applied to the F / E head cannot be completely blocked as the switching reliability of the relay decreases. .

Accordingly, an object of the present invention is to solve the above problems, by using a switching circuit of the transistor to configure the system so that the high frequency AC signal generated from the oscillation coil is completely blocked so that the F / E head is not applied. It is to provide a circuit that can be integrated.

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

1 is a block diagram of the present invention, the high frequency signal oscillated from the OSC coil 52 by the OSC driver 51 is mixed with the audio signal (S ₁ ) applied via the recording amplifier 50 to the R / P head The high frequency signal, which is applied to the 53 and recorded on the tape and oscillated at the other end of the OSC coil 52, is applied to the F / E head 54 via the buffer 20.

The high frequency signal applied to the buffer 20 is applied to the F / E head 54 when there is no dubbing function, that is, not in the dubbing mode, so that the video and audio signals written on the tape are deleted due to the operation of the recording mode. In the dubbing mode, the high frequency signal for controlling the buffer 20 is not applied to the F / E head 54 according to the output signal of the buffer control unit 10 applying the dubbing control circuit S ₂ . The high frequency signal generated by the OSC coil 52 is removed according to the operation of the high frequency removing unit 30 applying the dubbing control signal S ₂ .

2 is a detailed circuit diagram of the present invention, in which the buffer control unit 10 for controlling the buffer unit 20 by applying a dubbing control signal S ₂ includes a resistor R ₁ -R ₄ , a capacitor C ₄ , and a transistor. The buffer 20 corresponding to Q ₄ and applying a high frequency signal through the OSC coil 52 corresponds to resistors R ₄ and R ₅ and transistors Q ₁ and Q ₂ . 30 corresponds to resistors R ₁ -R ₄ and transistors Q ₄ , Q ₅ and grounded coil L ₁ .

Therefore, the high frequency signal generated at one end (C point) of the OSC coil 52 by the OSC driver 51 is applied to the collector of the transistor Q ₁ through the grounded capacitor C ₂ , at which time the video system When the dubbing mode is not in the dubbing mode, the transistor Q ₄ is not conducted because the dubbing control circuit S _{2 is} supplied with a logic " 0 " (low level) signal.

In this way, when the transistor Q ₄ is not conductive, the power supply Vcc applied to the collector of the transistor Q ₃ conducts the transistors Q ₁ and Q ₂ via the resistors R ₄ and R ₅ , respectively.

As the transistors Q ₁ and Q ₂ become conductive, a high frequency signal is applied to the F / E head 54 via the buffer transistors Q ₁ and Q ₂ to perform a tape erasing operation.

Since the dubbing control signal of the logic "0" signal does not conduct the transistors Q ₄ and Q ₅ , the high frequency signal applied to the buffer 20 cannot be removed through the grounded coil L ₁ .

However, in the dubbing mode, the dubbing control circuit S ₂ is applied as a logic " 1 " (high level) signal to conduct the transistor Q ₃ so that the transistors Q ₁ and Q ₂ are not conducting. The high frequency signal applied to the transistor Q ₁ collector of the buffer 20 through the OSC coil 52 is not applied to the F / E head 54, and the high frequency signal applied to the collector of the buffer transistor Q ₁ . Is removed from the grounded coil L ₁ via transistors Q ₄ and Q ₅ which are conducted by a dubbing control signal of a logic " 1 " signal.

Thus, a phenomenon in which the video signal recorded on the tape is deleted is obtained.

Since the high frequency signal generated at one end (point B) of the OSC coil 52 deletes only the audio track, the R / P head 53 can record a new audio signal.

As described above, according to the present invention, the mechanical switching circuit can be integrated into the electronic switching circuit, thereby lowering the production cost and increasing the audio signal deletion efficiency of the A / E head by making stable power generation.

Claims (1)

In a video system in which a high frequency signal generated by the OSC coil 52 by the OSC driving circuit 51 is applied to the F / E head 54, a buffer for outputting a driving control signal in accordance with the dubbing control circuit S ₂ . A buffer unit 20 for applying a high frequency signal generated by the driver 10 and the OSC coil 52 to apply a high frequency signal to the F / E head 54 according to the output signal of the buffer driver 10. And a high frequency removing unit 30 which removes the high frequency signal applied to the buffer unit 20 according to the dubbing control signal S ₂ by applying the high frequency signal to the grounded coil L ₁ . Voice dubbing circuit used.