JPS5853685Y2 - DIN output circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a DIN output circuit that takes out a DIN output from a low frequency amplifier circuit such as a cassette tape recorder.

FIG. 1 is a diagram showing an example of a conventional integrated circuit 1 for low frequency amplification, a speaker circuit 2, and a DIN output circuit.

The integrated circuit 1 mainly consists of differentially coupled transistors T1 . It consists of T2, a transistor T3 for voltage amplification, a transistor T4 constituting one driver stage, and push-pull connected transistors T5 and T6 constituting one power stage.

These are directly connected without going through an output capacitor.

SL and S2 are monitor changeover switches that are switched in conjunction with the monitor ON ON side or monitor OFF OFF side, and 53ts4 is a recording/playback changeover switch that is switched in conjunction with the recording R side or the playback P side.

And monitor changeover switch S1. Switch S2 to the OFF side, and turn the recording/playback selector switch S3. The configuration was such that when S4 was switched to the P side, the DIN output was taken out via the output resistor R□.

Considering the case where the DIN output of rice is connected to an external high-output amplifier (not shown) to drive an external speaker (not shown), the power supply Vcc is connected to the integrated circuit 1 and connected to the tape recorder. Since it is also connected to the motor, switch (not shown), etc. on the main unit side, these switch noises, hum sounds, etc. are amplified by being amplified by the external high-output amplifier via the path shown by the broken line in Figure 1. There was a risk that the external speaker would be driven and the speaker destroyed.

Furthermore, when the power supply Vcc is cut off, the integrated circuit 1 is driven by the back electromotive force of the motor, and the governor noise of the motor is inconveniently applied to the speaker via the same path as described above.

Furthermore, if the volume variable resistor (not shown) in the previous stage is maximized, the power level of the integrated circuit 1 will be saturated, resulting in the inconvenience that only the clipped output can be taken out as the DIN output. there were.

Therefore, in the present invention, the DIN output is taken out from the transistor T4 constituting one stage of the driver via the resistor R1 (see FIG. 2).

With this configuration, the DIN output can be taken out without a clip, and it is also possible to prevent noise such as switch noise, hum noise, motor noise, etc., from being mixed into the DIN output as described above. It will not destroy external speakers connected to high output amplifiers.

Furthermore, since a volume variable resistor is connected to the front stage,
It is also possible to vary the level of the DIN output.

[Brief explanation of the drawing]

The drawings show an integrated circuit for low frequency amplification, a speaker circuit, and a DIN output circuit, with FIG. 1 showing a conventional example and FIG. 2 showing an embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] A DIN output circuit is characterized in that a DIN output is derived from a driver stage of a low frequency amplifier circuit as a main amplifier, which has a volume variable resistor connected to its front stage and has one driver stage and one power stage.