JPH0233354Y2 - - Google Patents

Description

[Detailed description of the invention] This invention allows you to monitor from either the earphones or speakers when recording using an external microphone, and from only the earphones when recording using the built-in microphone. This invention relates to a tape recorder circuit that made possible the following.

When recording with a tape recorder, in order to check the state in which the recording is being made, conventionally, as shown in FIG. In addition to the recording amplification circuit 3, after further amplification, the audio signal is recorded on the magnetic head 5 and on the tape 6 via the recording/reproduction switch 4, while the audio signal amplified by the preamplification circuit 2 is also applied to the main amplification circuit 7. By connecting an earphone to the earphone jack 8, audio signals recorded from the earphone can be monitored. In such a case, in order to prevent howling when recording using the built-in microphone 1, switch the recording/playback switch 4.
The changeover switch 9, which is interlocked with the switch 9, is switched to the state shown in the figure, so that the speaker 10 is not operated. However, when the plug is inserted into the microphone jack 11 and an external microphone is used for recording, howling does not occur, so the speaker 1
When it is desired to perform monitoring using 0, since the speaker 10 is deactivated as described above, the monitor sound cannot be heard from the speaker.

The present invention eliminates these drawbacks and provides a tape recorder circuit that allows recording to be performed using an external microphone and to be monitored using either earphones or speakers.

The present invention will be explained below with reference to Fig. 2.
is a magnetic head for recording or reproducing audio signals on tape 16; 17 is a built-in microphone;
18 is a microphone jack to which an external microphone (not shown) can be connected; 19 is a preamplifier circuit; 20 is a recording amplification circuit that amplifies the audio signal from the preamplifier circuit 19; and 21 has an amplification effect when grounded. The main amplifier circuit has a muting terminal 22 that eliminates the noise, and its output side is connected to a speaker 24 via an earphone jack 23.
Reference numerals 25 and 26 indicate recording/reproduction changeover switches, and the illustrated state indicates the recording state. Reference numeral 27 denotes a first changeover switch, which is switched to a state different from that shown when an external microphone plug (not shown) is inserted into the aforementioned microphone jack 18. Reference numeral 28 denotes a second changeover switch, which is switched to a state different from that shown when an earphone plug (not shown) is inserted into the earphone jack 23. The first changeover switch 27
The second contact 29 at the center of the switch 2 is grounded, and the first contact 31, where the contact piece 30 is normally located,
6, the contact piece 32 of the second changeover switch 28 is connected to the normally located first contact 33,
Further, the second contact 34 of the second changeover switch 28 is connected to the muting terminal 22 of the main amplifier circuit 21.

The tape recorder circuit of the present invention is configured as described above, and when recording, the recording/playback switch 2 is switched.
5 and 26 have been switched to the illustrated state. The audio signal input to the built-in microphone 17 in this state is applied to the preamplifier circuit 19 and amplified. The amplified audio signal is applied to the recording amplification circuit 20, and after being further amplified, the recording/playback switch 25
The signal is applied to the magnetic head 15 via the magnetic head 15 and recorded on the tape 16. At this time, a part of the output of the preamplifier circuit 19 is also applied to the main amplifier circuit 21, but the muting terminal 22 of the main amplifier circuit 21 is grounded via the second and first changeover switches 28 and 27. Therefore, since the main amplifier circuit 21 is not operated, no sound is output from the speaker 24, and as a result, the speaker output is not fed back to the built-in microphone 17 and causes howling.

If you want to monitor the recorded content, insert the plug into the earphone jack 23.
The second changeover switch 28 is switched to a state different from that shown in the figure, and the muting terminal 2 of the main amplifier circuit 21
Since the ground of 2 is released, the preamplifier circuit 19
After the audio signal is amplified by the main amplifier circuit 21, it is added to the earphones and the sound is emitted from the earphones, so that the recorded content can be heard.

Next, when recording using an external microphone, when the plug is inserted into the microphone jack 18, the first changeover switch 27 is changed to a state different from that shown in the figure, so that the grounding of the muting terminal 22 of the main amplifier circuit 21 is It will be canceled.
Therefore, the audio signal obtained from the external microphone is amplified by the preamplifier circuit 19, and then applied to the magnetic head 15 via the recording amplification circuit 20 and the recording/reproduction switch 25 as described above, and is also applied to the main amplification circuit 21. After that, it enters the speaker 24 and drives the speaker 24, so this time the speaker 2
4 allows you to monitor the recorded content.
Note that by considering the position of the external microphone, the sound generated by the speaker 24 can be prevented from being fed back to the external microphone and causing howling.

Of course, you can also monitor using earphones by inserting a plug into the earphone jack.

When the recording and reproducing switches 25 and 26 are switched to a state different from that shown in the figure, the reproducing state is entered.

That is, the magnetic head 15 has previously recorded the tape 1.
The audio signal recorded in 6 is reproduced and applied to the preamplifier circuit 19 via the recording/reproducing switch 25, and further enters the main amplifier circuit 21 where it is amplified and then drives the speaker 24. Since the recording/reproducing switch 26 is turned off at this time, the muting terminal 22 of the main amplifier circuit 21 is not grounded under any conditions.

As mentioned above, the tape recorder circuit of the present invention has a first changeover switch connected in series to the muting terminal of the main amplifier circuit, which is switched by attaching and detaching the plug to the microphone jack, and a first changeover switch which is switched by attaching and detaching the plug to the earphone jack. Since the second switch and recording/playback switch are connected, when recording with the built-in microphone in recording mode, insert the earphone plug into the earphone jack and turn off the second switch. This shuts off the muting terminal and operates the main amplifier circuit, allowing the audio signal applied to the built-in microphone to be monitored using only the earphones. When recording with an external microphone, connect the external microphone plug to the microphone jack. Turn off the first changeover switch by inserting the
By shutting off the mutating terminal and operating the main amplifier circuit, the audio signal applied to the external microphone can be directly monitored from the speaker, and by inserting the earphone plug into the earphone jack, it can be monitored from the earphone. In addition, since the muting terminal is cut off by the recording/reproducing switch during reproduction, the main amplifier circuit can be operated at all times, which is practical.

[Brief explanation of the drawing]

FIG. 1 is a conventional tape recorder circuit diagram, and FIG. 2 is a tape recorder circuit diagram of the present invention. 17...Built-in microphone, 18...Microphone jack, 19...Preamplifier circuit, 20
... Recording amplification circuit, 21 ... Main amplification circuit, 22 ...
...Muting terminal, 23...Earphone jack, 24...Speaker, 25, 26...Recording/playback switching switch, 27...First switching switch, 28...
...Second changeover switch.

Claims (1)

[Scope of utility model registration request] a preamplifier circuit connected to the magnetic head; an external microphone connected to the preamplifier circuit via a built-in microphone and selectively a microphone jack; and an external microphone connected to the preamplifier circuit to drive a speaker. a main amplifier circuit connected in series to the muting terminal of the main amplifier circuit, which is switched by attaching or detaching a plug to the microphone jack, and a first changeover switch which is switched by attaching or detaching the plug to the earphone jack. It consists of a second switch and a recording/playback switch. When recording with the built-in microphone in recording mode, insert the earphone plug into the earphone jack and turn off the second switch to turn off the muting terminal. When the main amplifier circuit is shut off and the main amplifier circuit is activated, the audio signal applied to the built-in microphone can be monitored using only the earphones, and when recording is performed using an external microphone, by inserting the external microphone plug into the microphone jack. Turn off the first selector switch, cut off the muting terminal, operate the main amplifier circuit, monitor the audio signal applied to the external microphone from the speaker as it is, and insert the earphone plug into the earphone jack. A tape recorder circuit is characterized in that it is possible to monitor with earphones, and when playing back, a muting terminal is cut off by a recording/reproducing switch and a main amplifier circuit is always operated.