JPH021683Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder, and particularly to a control circuit thereof. 2. Description of the Related Art Recently, an audio device called a karaoke machine has become popular, which mixes a playback signal of an instrumental music signal recorded on a magnetic tape with a singing voice obtained from a microphone and outputs the mixture from a speaker. When using such a sound device, your voice will be played along with the instrumental music signal from the speaker, but if your voice is too loud, you will no longer be able to hear the instrumental music playing, making it difficult to synchronize the timing with the performance signal. This problem becomes more noticeable when a headphone is used. In this case, it is possible to adjust the timing by attenuating the level of the signal obtained from the microphone by adjusting the variable resistor, but if the mixed signal is being recorded on magnetic tape, the mixing The balance of the signal is lost, and only the instrumental music signal is recorded prominently. The present invention aims to provide a control circuit that is improved in this respect, and will be described in detail below with reference to the drawings. The illustrated circuit is an embodiment of the present invention, and in the figure, 1 is a microphone, and 2 is a microphone amplifier circuit to which a microphone signal obtained from the microphone 1 is input and which amplifies the signal. , 3 is the amplifier circuit 2 for the microphone.
A first variable resistor is applied with a microphone signal from the first variable resistor and adjusts its level. 4 is a playback head constituting a tape recorder in which the first tape on which the instrumental music signal is recorded is used; 5 is a preamplifier circuit into which the playback signal played by the playback head 4 is input and which amplifies the signal; ,6
is a second variable resistor to which the reproduction signal amplified by the preamplifier circuit 5 is applied and adjusts its level. 7 is a first buffer amplifier circuit into which the microphone signal whose level has been adjusted by the first variable resistor 3 is input; and 8 which is into which the reproduced signal whose level has been adjusted by the second variable resistor 6 is input. A second buffer amplifier circuit 9 inputs the microphone signal from the first buffer amplifier circuit 7 to its input terminal 12 through resistors 10 and 11, and receives the reproduced signal from the second buffer amplifier circuit 8 through the resistor 13. 14 is a headphone jack into which a headphone plug is inserted; a signal terminal 16 connected to the output terminal of the main amplification circuit 9 via a resistor 15; Terminal 17 and switching piece 1
It is equipped with 8. Reference numeral 19 denotes a speaker to which the output signal of the main amplifier circuit 9 is applied through the switching contact piece 18 when the headphone plug is not inserted into the headphone jack 14 . Reference numeral 20 denotes a recording amplifier circuit, into which the microphone signal from the first buffer amplifier circuit 7 is input through a resistor 21 and the playback signal from the second buffer amplifier circuit 8 is input through a resistor 22;
3 is a recording head to which the output signal of the recording amplifier circuit 20 is applied and records the signal onto the second tape; 24 is a bias oscillation circuit that supplies a bias signal to the recording head 23; 25 is a control switch that is closed when the headphone plug is inserted into the headphone jack 14 ; 26, the collector is connected to the resistors 10 and 11 via a resistor 27;
is a level control transistor connected to the connection point A of , and whose emitter is grounded.
Its base includes a resistor 28 and the control switch 25
Connected to power via. In such a configuration, the resistors 10, 27, etc. attenuate the level of the microphone signal input from the first buffer amplifier circuit 7 to the main amplifier circuit 9 to an appropriate level when the level control transistor 26 is in a conductive state. It is set to the desired value. The control circuit of the present invention is constructed as described above, and the operation of this circuit will now be described. When the headphone plug is not inserted into the headphone jack 14 , the switching contact piece 18 is in contact and the control switch 25 is open, so that no bias is applied to the base of the level control transistor 26. The control transistor 26 is non-conducting. In such a state, when the first tape side is played back, the tape recorder enters the playback mode, and the instrumental music signal recorded on the magnetic tape is played back by the playback head 4. The reproduction signal reproduced by the reproduction head 4 is input to a preamplifier circuit 5 and amplified, and then applied to a second variable resistor 6 to adjust its level. In addition, the singing voice emitted by the user is converted into an electrical signal by the microphone 1, and is converted into an electric signal by the microphone amplifier circuit 2.
is input. The microphone signal input to the microphone amplifier circuit 2 is amplified and then applied to the first variable resistor 3 to have its level adjusted. The reproduced signal whose level has been adjusted by the second variable resistor 6 passes through the second buffer amplifier circuit 8 and is then input to the main amplifier circuit 9 through the resistor 13.
Further, the microphone signal whose level has been adjusted by the first variable resistor 3 passes through the first buffer amplifier circuit 7 and then through the main amplifier circuit 9 through resistors 10 and 11.
is input to the input terminal 12 of the . Therefore, the reproduction signal and the microphone signal are mixed and input to the main amplifier circuit 9. The microphone signal and playback signal thus input to the main amplifier circuit 9 are amplified and then sent to the headphone jack 14.
The signal is applied to the speaker 19 through the switching contact piece 18 and the sound is emitted. In this way, the speaker 19
Therefore, the microphone signal and the reproduced signal are mixed and emitted, and the user and the listener can hear the signal. Although the reproduction operation is performed as described above, the recording operation of such a signal will be explained next. When the tape recorder on the second tape side performs a recording operation, the recording amplifier circuit 20 and the bias oscillation circuit 24 become operational, and the second tape is driven to perform a recording operation. A microphone signal that has passed through the first buffer amplification circuit 7 is applied to the input terminal of the recording amplification circuit 20 through a resistor 21, and a reproduced signal that has passed through the second buffer amplification circuit 8 is applied to the input terminal of the recording amplification circuit 20.
2. Therefore, the reproduction signal and the microphone signal are mixed and input to the recording amplifier circuit 20. The microphone signal and playback signal input to the recording amplifier circuit 20 in this manner are amplified and then sent to the bias oscillation circuit 2.
The signal is applied to the recording head 23 together with the bias signal from the magnetic tape 4, and is recorded on the second magnetic tape. If you play back the magnetic tape recorded in this way, you will be able to hear your own singing voice recorded along with the instrumental music signal. As described above, the reproduction/listening operation and the recording operation are carried out by the speaker 19. Next, a case will be described in which the speaker 19 is used by one person and is reproduced and listened to by a head-on. When the headphone plug is inserted into the headphone jack 14 , the switching contact piece 18 is opened, the signal path to the speaker 19 is cut off, and the control switch 25 is closed. When the control switch 25 is closed, a bias current flows through the control switch 25 and the resistor 28 to the base of the level control transistor 26, turning the control transistor 26 into a conductive state. When the first tape side is reproduced in such a state, the microphone signal and the reproduction signal are mixed and input to the main amplifier circuit 9 as described above, but in this case, since the level control transistor 26 is in a conductive state, The level of the microphone signal input from the first buffer amplifier circuit 7 to the main amplifier circuit 9 is attenuated. The mixed signal thus input to the main amplifier circuit 9 is amplified and then applied to the signal terminal 16 of the headphone jack 14 and listened to by the headphone. The signal obtained from the microphone 1 is at a lower level than the level of the instrumental signal reproduced by the reproduction head 4, making it easier to hear the instrumental signal and therefore making it easier to synchronize with the performance. I can do it. As described above, the reproduction/listening operation using the headphone is performed. Next, the recording operation of the second tape in such a state will be explained. When the recording operation on the second tape side is performed, the recording operation state is configured as described above, and the microphone signal from the first buffer amplifier circuit 7 is transmitted to the recording amplifier circuit 20 through the resistor 21 and to the second buffer amplifier circuit 8. A playback signal from is inputted through the resistor 22. The level of the microphone signal from the first buffer amplifier circuit 7 is controlled by a level control transistor 26.
The first variable resistor 3 and the second variable resistor 3 are connected to the second tape without being attenuated even when
The level set by the variable resistor 6 results in well-balanced recording. As explained above, according to the present invention, in a tape recorder configured to mix and reproduce the reproduction signal of the magnetic tape and the microphone signal from the microphone, the mixed signal is listened to by the headphone. In this case, the level of the microphone signal is attenuated, making it easier to hear the instrumental music signal that is the playback signal, and making it easier to synchronize with the performance signal. Since only the signal level is attenuated, the present invention has the feature that the balance of the recording level is not disturbed. In addition, since the level attenuation of the microphone signal is performed by inserting a headphone plug into the headphone jack, operability is excellent, and the control circuit of the present invention is ideal as a control circuit for a sound device called a karaoke. It is something.

[Brief explanation of the drawing]

The illustrated circuit is one embodiment of the control circuit of the present invention. Explanation of main drawing numbers, 1... Microphone, 2...
...Microphone amplifier circuit, 4...Reproduction head, 5...Preamplifier circuit, 9...Main amplifier circuit, 1
4... Headphone jack, 19... Speaker, 20... Recording amplifier circuit, 23... Recording head, 25... Control switch, 26... Level control transistor.

Claims (1)

[Scope of utility model registration request] A preamplifier circuit that amplifies the reproduction signal reproduced by the reproduction head, a microphone amplifier circuit that amplifies the microphone signal obtained from the microphone, and a reproduction signal from the preamplifier circuit and an amplifier circuit for the microphone. a headphone jack having a main amplifier circuit to which the microphone signals from the main amplifier circuit are mixed and input, a signal terminal to which the output signal of the main amplifier circuit is applied, and a switching piece for controlling the signal supply to the speaker; A recording amplifier circuit to which the reproduction signal from the preamplifier circuit and the microphone signal from the microphone amplifier circuit are mixed and input, and to which the recording head is connected as a load; a control switch that is closed when the microphone plug is inserted; and when the control switch is in the closed state, it is biased and becomes conductive, and attenuates only the level of the microphone signal input to the main amplifier circuit. A tape recorder control circuit consisting of level control transistors.