JPS6331274Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a power supply circuit for a tape recorder that uses two power sources: AC power and DC power. (b) Prior art Figure 1 shows a conventional power supply circuit. In FIG. 1, 1 is an AC power transformer, 2 is a rectifier circuit connected to the secondary side of the power transformer 1, 3 is a DC power source using a battery, and 4 is an AC power source rectified by the rectifier circuit 2.
a switch for switching between the power source and the DC power source 3;
5 is an electrolytic capacitor, and 6 and 7 are an amplifier circuit and a motor to which AC power or DC power via the changeover switch 4 is applied. 8 is an input terminal for a signal input to the amplifier circuit 6, and 9 is a speaker. According to such a conventional circuit, the changeover switch 4 is
When the switch 4 is switched to the DC terminal (AC), the rectified voltage of the AC power supply is applied to the amplifier circuit 6 and the motor 7, and when the switch 4 is switched to the DC terminal (DC), the voltage of the DC power supply 3 is amplified. Circuit 6 and motor 7
is applied to By the way, the working voltage range of the mechanism used in a tape recorder is determined by the rated voltage of the motor that drives it, and the upper limit of working voltage is usually 20% higher than the rated voltage of the motor, and 30% higher than the rated voltage of the motor.
The lower limit of the operating voltage is the lower limit. Therefore, even if a tape recorder uses a DC power supply, the mechanism must operate normally until the voltage drops by 30% of the rated voltage, so the motor 7 must be directly powered as shown in Figure 1. It is configured to apply a voltage. In addition, the power transformer is designed so that even when using AC power, the voltage range used by the mechanism described above will not be exceeded. However, due to the characteristics of power transformers, when the output is increased, the current consumption increases.
The secondary voltage of the power transformer decreases, and the rectified voltage applied to the amplifier circuit becomes lower than the voltage applied in the case of a DC power supply, resulting in a smaller output and
The output is only around 70% of the output when using DC power. In order to improve this, it is necessary to increase the secondary voltage of the power transformer so that it does not drop much compared to the DC power supply voltage when current consumption increases.
However, if the secondary voltage is increased, the rectified voltage will exceed the operating voltage range of the motor when the current consumption is low, that is, when the volume is kept low. (c) Purpose of the invention The present invention provides a power supply circuit for a tape recorder with the purpose of solving the above-mentioned problems. (d) Example of the invention An example of the invention is shown in FIG. In FIG . 2, parts that are the same as those in FIG. 4 is connected to an interlocking switch 12 which is interlocked with the switch 4. The regulator circuit 11 includes a transistor 1
3, a Zener diode 14, a resistor 15, and capacitors 16 and 17. In the present invention, when an AC power source is used, the secondary voltage of the power transformer 1, that is, the rectified voltage, is set in advance to be higher than the DC power source voltage. Since the present invention is constructed in this manner, when the changeover switch 4 is switched to the AC terminal side, the interlocking switch 12 is also switched to the AC terminal side in conjunction with this, opening the input and output of the regulator circuit 11 . The regulator circuit 11 is connected to the power line 10 of the motor 7. Therefore, when using an AC power supply, the rectified voltage is applied to the amplifier circuit 6 in a state higher than the DC power supply voltage, so when used at high output, the current consumption increases and the secondary voltage of the power transformer increases. Even if the output decreases by a certain amount, the speaker can still be driven with sufficient output. Also, when the output is small and consumes little current , the voltage is dropped by a predetermined voltage by the regulator circuit 11 and applied to the motor 7, so that a voltage exceeding the operating voltage range is not applied to the motor 7. When the changeover switch 4 is switched to the DC terminal side, the input and output of the regulator circuit 11 can be short-circuited by the interlocking switch 12.
A voltage can be applied to the motor 7 within the normal motor operating voltage range without lowering the DC power supply voltage by the regulator circuit 11 . (e) Effects of the invention As mentioned above, the invention has a rectifier circuit.
In a tape recorder equipped with an AC power source and a DC power source, these power sources are selectively applied to the amplifier circuit and motor through a changeover switch.
The rectified voltage of the AC power source is set higher than the voltage of the DC power source in advance, a voltage regulator circuit is connected to the power line of the motor, and an interlocking switch that interlocks with the changeover switch is connected between the input and output of the regulator circuit. , when the AC power source is used, the interlocking switch is released, the rectified voltage is applied to the amplifier circuit, the voltage is dropped by a predetermined voltage by the voltage regulator circuit, and the voltage is applied to the motor, and the DC voltage is applied to the motor.
When using a power supply, the input and output of the voltage regulator circuit are short-circuited by the interlocking switch, and the DC voltage is applied to the amplifier circuit and the motor without dropping, so the tape recorder can be operated very easily when using an AC power supply. Even if the current consumption increases due to output use and the secondary voltage of the power transformer decreases,
Since it is set in advance to be higher than the DC power supply voltage, the voltage applied to the amplifier circuit can be made substantially the same as the DC power supply voltage, and the speaker can be driven with sufficient output. When using a tape recorder with a small output when using AC power, the rectified voltage is dropped by the voltage regulator circuit and applied to the motor, so a voltage exceeding the working voltage range is not applied, and DC When using the power supply, the input and output of the voltage regulator circuit are short-circuited to drive the motor within an appropriate working voltage range.

[Brief explanation of the drawing]

FIG. 1 is a conventional circuit configuration diagram, and FIG. 2 is a circuit diagram of the present invention. 1... Power transformer, 2... Rectifier circuit, 3...
DC power supply, 4... selector switch, 6... amplifier circuit,
7...Motor, 11 ...Regulator circuit, 12
...Interlocking switch.

Claims (1)

[Scope of utility model registration request] Equipped with an AC power supply with a rectifier circuit and a DC power supply,
In a tape recorder in which these power sources are selectively applied to an amplifier circuit and a motor through a changeover switch, the rectified voltage of the AC power source is set higher than the voltage of the DC power source, and the voltage is applied to the power line of the motor. connecting a regulator circuit and connecting an interlocking switch that interlocks with the changeover switch between the input and output of the regulator circuit, and opening the interlocking switch when the AC power source is used;
A rectified voltage is applied to the amplifier circuit, and the voltage is dropped by a predetermined voltage by the voltage regulator circuit and applied to the motor. When using a DC power supply, the input and output of the voltage regulator circuit are short-circuited by the interlocking switch to reduce the DC voltage. 1. A power supply circuit for a tape recorder, characterized in that the power supply circuit is configured to apply voltage to an amplifier circuit and a motor without causing any voltage to be applied to the amplifier circuit and the motor.