JPS606891Y2 - tape recorder circuit - Google Patents

Description

[Detailed description of the invention] This invention uses an external microphone instead of the built-in condenser microphone to record when the tape recorder is switched from the recording state to the stopped state. The present invention relates to a tape recorder circuit which prevents pop noise from being generated from a line output or a speaker.

Since there is less concern about howling when recording with an external microphone,
Speaker monitoring is possible, and since the speaker monitor signal supply path is in an operating state when recording with an external microphone while performing speaker monitoring, the pop noise is likely to occur at that moment when switching to the stopped state.

Therefore, when monitoring the speaker using an external microphone, the present invention utilizes the power supply circuit of the built-in condenser microphone, which is not in use due to the operation power circuit being cut off, to activate the muting circuit and bring the external microphone into recording mode. The pop noise that occurs when switching from the state to the stopped state can be eliminated by the delay operation of the muting circuit.

Embodiments of the tape recorder circuit of the present invention shown in the drawings will be described below.

In the figure, 1 is a built-in condenser microphone, 2 is an external microphone jack, 3 is a line input jack, 4 is a microphone input and line input amplifier, 5 is a recording/playback amplifier,
6 is a line output amplifier, ? a, 7b, 7c, and 7d are recording/playback switching switches; 8a, 8b are microphone input and line input switching switches; 9 is the external microphone jack 2.
10 is a line output terminal, and 11 is a speaker.

The recording/playback switch 7a connected to the input side of the recording/playback amplifier 5 has its recording terminal R connected to the output side of the amplifier 4, and its playback terminal P connected to the signal supply path 12 from the playback head. It is connected.

Further, the recording/playback switch 7b connected to the output side of the recording/playback amplifier 5 has its recording terminal R connected to a signal supply path 13 to the recording head, and its playback terminal P connected to a muting circuit 14. It is connected.

10B is a power supply that supplies operating voltage to the built-in condenser microphone 1, and its voltage supply line is connected to the recording/playback switch 7.
d recording terminal R-mic/line input selector switch 8b
When the built-in condenser microphone 1 is in operation with this power supply 10B, the voltage is applied to the base of the amplification transistor of the line output amplifier 6 through the diode 15. is applied to make the amplifier 6 inoperative.

Therefore, the monitor signal through the monitor signal supply line 16 connected from the output side of the amplifier 4 which amplified the microphone input to the input side of the line output amplifier 6 is not outputted from the speaker 11.

The muting circuit 14 includes a recording/playback selector switch 7.
Resistors 17 and 18 are connected in series between the playback terminal P of the output amplifier 6 and the input side of the line output amplifier 6, and the resistors 17 and 18
It consists of a muting transistor 19 whose collector and emitter are connected between the connection midpoint of the transistor 19 and ground, a resistor 20, 21 connected to the base of the transistor 19, and a charging/discharging capacitor 22. 2
2 is a 10B power supply for operating the built-in condenser microphone 1.
is connected.

That is, the voltage from the power supply +B is applied to the capacitor 22 through the switch 23 and the diode 24, which are closed when the tape recorder is stopped, and the switch 23 is used to move the tape drive mechanism from the stop position to the operating position. It becomes open state.

Also, in a recording state where the recording/playback selector switches 7a to 7d are at the recording terminal R, when the microphone/line input selector switch 8at8b is changed to the line terminal LINE, or when the jack switch 9 is switched to the in terminal rule, the diode 25 A voltage from the power supply 1B is applied to the capacitor 22 through the capacitor 22.

The tape recorder circuit of the present invention is constructed as described above, and its operation will be explained below.

When the tape recorder is stopped, the capacitor 22 of the muting circuit 14 is in a charged state by closing the switch 23.

When switching to the playback state, the recording/playback amplifier 5
At the same time when a signal from the reproducing head is applied to the input side of the muting circuit 14, the transistor 19 is in a conductive state for a period of time during which the capacitor 22 and the resistor 21 are discharged.
is running, so the moment you switch from stop to play,
The reproduced output is muted, and then the transistor 19 becomes non-conductive, so that the reproduced signal is output to the speaker 11 via the line output amplifier 6.

Next is the recording/playback switch? a, 7b, 7c.

A recording state in which the terminal 7d is switched to the recording terminal R will be explained.

When recording with the built-in condenser microphone 1, selector switches 8a and 8b are set to the microphone terminal MIC, and jack switch 9 is set to the microphone terminal MIC.
is located at the out terminal OUT, so that at the same time that the built-in condenser microphone 1 is supplied with an operating voltage, a cutoff voltage is applied to the transistor of the line output amplifier 6, so that speaker monitoring cannot be performed.

Therefore, the signal from the built-in condenser microphone 1 is amplified by amplifiers 4 and 5 and then supplied to the recording head.

In this state, when you insert the external microphone plug into jack 2 to use an external microphone, the jack switch 9
is switched from the out terminal -0UT to the in terminal surface, and the built-in condenser microphone 1 becomes inactive.

At this time, the power supply 1B is connected to the muting circuit 1 through the in terminal IN of the jack switch 9 and the diode 25.
4, and the muting circuit 14 is put into operation.

On the other hand, the cut-off transistor in the line output amplifier 6 becomes operational, and the monitor signal from the monitor signal supply path 16 is amplified to enable speaker monitoring.

The above operation is performed by connecting the selector switches 8a and 8b to the line terminal LI.
The same thing applies when recording line input switched to NE.

The tape recorder circuit of the present invention keeps the muting circuit active during the above-mentioned external microphone recording or line input recording, and when switching from the recording state to the stop state, the output side of the recording/playback amplifier 5 are to be muted by a specific number by the capacitor 22 and resistor 21 of the muting circuit 14.

Therefore, when switching from the recording state to the stop state, the recording and playback selector switches 7a, 7b, 7c, and 7d instantly switch to the playback terminal P.
This changeover switch mutes the amplifier output for a certain period of time even if pulse-like switching noise occurs, and the line output terminal 10 or speaker 11
No noise will be generated from the

As described above, the tape recorder circuit of the present invention has a microphone on the playback output side of the recording/playback amplifier whose input/output circuit is switched by the recording/playback switch, which is independent of the speaker monitor signal supply path when recording using an external microphone. The muting circuit is connected to the muting circuit, and the muting circuit is activated by the built-in condenser microphone's power supply circuit when recording using an external microphone. Therefore, when the built-in condenser microphone is turned off and switched to the external microphone, the muting circuit is activated at the same time as The muting circuit is activated using the power supply, and when the external microphone recording state is switched to the stopped state, the muting circuit operates for a certain period of time, so that the switching noise of the recording/playback switch is removed from the line output terminal or speaker. This can eliminate concerns about output.

[Brief explanation of drawings]

The figure is a circuit diagram of the tape recorder of the present invention. 1...Built-in condenser microphone, 2...
External microphone jack, 3... Line input jack, 5... Recording/playback amplifier, 7a, 7b,
7c, 7d... Recording/playback selector switch, 8a,
8b...Mic/line input selector switch, 9
... Jack switch, 11 ... Speaker, 14 ... Muting circuit.

Claims (1)

[Scope of utility model registration request] The built-in condenser microphone and external microphone can be selectively used during recording, and the output of the microphone input amplifier is guided to the recording head through the recording/playback amplifier, and when an external microphone is used, part of the output of the microphone input amplifier is output. In a tape recorder configured to enable speaker monitoring through a recording/playback amplifier, and to guide a playback signal from a playback head to the output amplifier during playback through a recording/playback amplifier, the playback output side of the recording/playback amplifier When recording using an external microphone, connect a muting circuit that does not depend on the speaker monitor signal supply path.The muting circuit is activated by the power supply circuit of the built-in condenser microphone when recording using an external microphone, and is then stopped. A tape recorder circuit characterized in that the muting circuit is configured to operate for a certain period of time when switched.