JPS6131433Y2 - - Google Patents

Description

[Detailed description of the invention] This invention enables the user to turn off the power switch of the tape recorder drive circuit by the end of the sleep signal or the end of the tape when receiving a radio broadcast using a sleep signal and recording the radio broadcast on a tape. This invention relates to a power supply device for a radio tape recorder with a clock, which turns off a switching circuit for driving the radio tape recorder and turns off the power at the later time.

In a conventional radio tape recorder with a clock, if you set the sleep device so that you can go to bed while listening to radio broadcasts, and then try to record the radio broadcasts, the power will be turned off due to the end of the sleep signal before the tape reaches the end of the tape. There is an inconvenience when it happens. For example, if you set a sleep device, the power will generally turn off automatically after one hour.
If you try to record that radio broadcast minutes later,
Ten minutes after the tape ran and recording started, the power was turned off due to the end of the sleep signal. That is, there is a drawback that the power may be cut off in the middle of a radio program being recorded. Moreover, since the power is turned off while the tape is running, the pinch roller of the tape recorder mechanism and the capstan remain in pressure contact with each other. Furthermore, due to the collector-emitter saturation voltage of the switching transistor in the switching circuit for driving a radio tape recorder, the power supply voltage applied to the amplifier and tape recorder drive motor may be lost, and a large inrush current may occur when the switching transistor is turned on. This has various problems, such as the possibility that the switching transistor may be damaged due to the current flowing therein.

This invention takes into account the above-mentioned conventional problems, and when recording a radio broadcast after setting the sleep device, it is possible to run the tape to the end and record even if the sleep signal disappears, and further,
The device has a structure that reduces the voltage loss of the DC power supply applied to the amplifier and prevents the inrush current from flowing into the switching transistor. This will be explained in detail.

In the figure, 1 is a 12V DC power supply, and 2 is a first power switch of a tape recorder drive circuit, which will be described later, and one end of which is connected to the positive terminal of the DC power supply 1, and which operates the play button, record button, and fast forward button of the tape recorder. , rewind button, or the like is pressed, and is automatically turned off when the tape ends due to tape running. 3 is the tape recorder terminal T;
Radio terminal R and sleep timer terminal S
The tape recorder terminal T is connected to the other end of the first power switch 2, and the radio terminal R is connected to the positive terminal of the DC power supply 1. Reference numeral 4 denotes an alarm switch, and an off terminal (OFF) is connected to a switching piece of the first switching switch 3 via a first resistor 5. A second changeover switch 6 is linked to the first changeover switch 3, and has a tape recorder terminal T, a radio terminal R, and a sleep timer terminal similarly to the first changeover switch. 7 is a clock LSI which is the main component of the clock, and the sleep signal output terminal Sl is connected to the sleep timer terminal S of the second changeover switch 6 via the first diode 8 in the forward direction. When each switching piece of the second switching switch 3, 6 is connected to the sleep timer terminal S, a +1.5V sleep signal is output for one hour with respect to the ground, and the alarm signal output terminal A is connected to the forward direction. is connected to the ON terminal (ON) of the alarm switch 4 through the second diode 9 of It is designed to output an alarm signal of +1.5V to earth for one hour. 10,11
12 is a second resistor and a third diode for backflow prevention connected in series between the other end of the first power switch 2 and the sleep timer terminal Sl of the second changeover switch 6; a third resistor connected between the switching piece and the negative terminal of the DC power supply 1;
Reference numeral 13 designates a first auxiliary switching transistor whose base is connected to the switching piece of the second changeover switch 6, and whose emitter is connected to the negative side terminal of the DC power supply 1 via a fourth resistor 14. 15 and 16 are fifth and sixth resistors connected in series between the positive terminal of the DC power supply 1 and the collector of the first auxiliary switching transistor 13; 17 is an emitter connected to the positive terminal of the DC power supply 1; The second auxiliary switching transistor has a base connected to a connection point between the fifth and sixth resistors 15 and 16. 1
Reference numerals 8 and 19 indicate a seventh resistor connected in series between the collector of the second auxiliary switching transistor 17 and the negative terminal of the DC power supply 1, and a resistor for preventing inrush current into a switching circuit for driving a radio tape recorder, which will be described later. The first capacitor 20 is a first main switching transistor whose base is connected to the connection point of the seventh resistor 18 and the first capacitor 19 via the eighth resistor 21 for base-emitter voltage correction, and whose emitter is connected to the DC power supply. It is connected to the negative side terminal of 1. 22 is a ninth resistor for bias bleeder connected between the base and emitter of the first main switching transistor 20; 23 is a second main switching transistor connected in parallel to the first main switching transistor 20; It has the same characteristics as the first switching transistor 20. 24 is the seventh resistor 18 and the first capacitor 19
connection point and the second main switching transistor 2
A tenth resistor 25 is connected between the base of the second main switching transistor 23 for correcting the voltage between the base and emitter of the second main switching transistor 23, and a tenth resistor 25 is a bias bleeder resistor connected between the base and the emitter of the second main switching transistor 23. The 11th resistor (SG) is the first and second main switching transistor 2
0, 23 and the 8th to 11th resistors 21, 22,
A switching circuit for driving a radio tape recorder constituted by 24 and 25, and 26 has a power terminal connected to the positive terminal of the DC power supply 1 and the connection point of each collector of the first and second main switching transistors 20 and 23. 27 is a speaker connected to the output terminal of the amplifier 26, 28 is a second capacitor connected between the positive terminal of the DC power supply 1 and the collector of the first main switching transistor 20, 29 and 30 are A second power switch and a tape recorder driving motor are connected in series with each other and connected in parallel with the second capacitor 28.
The power switch 29 is interlocked with the first power switch 2. 31 is a tape recorder drive circuit whose power supply terminal is connected to the positive terminal of the DC power supply 1 and the collector of the first main switching transistor 20; 32 is a magnetic head connected to the tape recorder drive circuit 31; and 33 is a tape recorder drive circuit whose power supply terminal is connected to the collector of the first main switching transistor 20. A radio receiving circuit is connected between the positive terminal of the DC power supply 1 and the collector of the first main switching transistor 20, 34 is an antenna connected to the radio receiving circuit 33, and 35 is a tape recorder terminal T and a radio terminal. The terminal R is a radio-tape recorder changeover switch connected to a tape recorder drive circuit 31 and a radio reception circuit 33, respectively, and a changeover piece is connected to an input terminal of an amplifier 26.

Next, the operation of the above embodiment will be explained.

First, when performing normal recording or playback operations with a tape recorder, connect the switching piece of the alarm switch 4 to the off terminal (OFF), and connect the first and second switching switches 3 and 6 and the radio-tape recorder switching switch. Each of the 35 switching pieces is connected to a tape recorder terminal T, respectively. Then, when a desired button such as the play button or the record button is pressed, the first and second power switches 2 and 29 are turned on, and a portion of the DC power source 1 is switched on to the first power switch 2, the first changeover switch 3, and the The signal is applied to the base of the first auxiliary switching transistor 13 via the first resistor 5 and the alarm switch 4, and the first auxiliary switching transistor 13 is turned on.
Therefore, when the first auxiliary switching transistor 13 is turned on, the second auxiliary switching transistor 17 is turned on, and the first and second main switching transistors 20 and 23 are also turned on.

Here, when the second auxiliary switching transistor 17 is turned on, a rush current of about 10 A attempts to flow into the input terminal I of the radio tape recorder driving switching circuit (SC), but this is blocked by the charging of the first capacitor 19. , the first and second main switching transistors 20 and 23 are not turned on instantaneously. If the first capacitor 19 is not inserted, a large inrush current exceeding the ratings of the main switching transistors 20 and 23 will flow through the main switching transistors 20 and 23.
flows into both main switching transistors 2
0,23 are destroyed.

And both main switching transistors 2
0,23 turns on, the amplifier 26 is energized,
And the tape recorder drive circuit 31 operates. On the other hand, when the second power switch 29 is turned on, the motor 3
0 rotates, the tape is run, and recording or playback operations are performed. When the end of the tape is reached, an automatic stop device is activated to turn off the first and second power switches 2 and 29, thereby turning off the power.

By the way, in the above-mentioned operation, the power supply voltage applied to the amplifier 26 and the motor 30 is not the 12V of the DC power supply 1 directly applied, but the power supply voltage applied to the first and second main switching transistors 2.
0, 23 collector-emitter voltage (V _CE
There is some loss due to _S ). For example, for both main switching transistors 20 and 23,
The case where a current of 1A flows will be explained.

If the second main switching transistor 23
If only the first main switching transistor 20 is inserted without the first main switching transistor 20 being inserted, the voltage between the collector and emitter of the first main switching transistor 20 is approximately 0.2V, and the power supply voltage of the DC power supply 1 is reduced by this 0.2V. This means that it cannot be used effectively. However, in the above embodiment, since the two main switching transistors 20 and 23 with the same characteristics are connected in parallel, 0.5 A flows through each of the first and second main switching transistors 20 and 23. DC power supply 1 applied to amplifier 26
The voltage will result in a loss of approximately 0.1V. Therefore, the more transistors are connected in parallel, the more the amplifier 2
The voltage loss of the DC power supply 1 applied to the DC power source 6 is reduced. This slight difference in voltage loss has a large effect when the voltage value of the DC power source 1 decreases due to deterioration of the DC power source 1 such as a battery.

Further, transistors have variations in base-emitter voltage (V _BE ) when the transistor is turned on. Therefore, if the eighth and tenth resistors 21 and 24 are not connected to the bases of both main switching transistors 20 and 23, respectively, both main switching transistors 2
If one of the transistors 0 and 23 is momentarily completely turned on and the other is partially turned on, the current from the amplifier 26 will flow to the transistor that is completely turned on. The portion flows in;
Only a small amount of current flows through a transistor that is in an incompletely turned on state. Therefore, an attempt was made to connect a plurality of main switching transistors 20 and 23 in parallel to reduce the collector-emitter voltage and thereby reduce voltage loss. The above-mentioned advantages of doing so disappear. Therefore, in the embodiment, both main switching transistors 20 and 23 are connected by the eighth and tenth resistors 21 and 24.
Because it absorbs variations in the base-emitter voltage of both main switching transistors 2
0 and 23 are turned on simultaneously and completely. In addition,
The 9th and 11th resistors 22 and 25 are connected as bias bleeder resistors for both main switching transistors 20 and 23, but they have higher resistance than the 8th and 10th resistors 21 and 24 for correction. Therefore, the function and effect of correcting the base-emitter voltages of the main switching transistors 20 and 23 of the eighth and tenth resistors 21 and 24 are not impaired.

Next, when receiving a radio broadcast, each switch of the first and second switch 3, 6 and radio-tape recorder switch 35 is switched to the radio terminal R, and the switch of the alarm switch 4 is switched to the radio terminal R. When connected to the off terminal (OFF), radio broadcasts are received by the same operation as the tape recorder described above. Then, by switching the switch of the alarm switch 4 to the ON terminal (ON) and setting a desired time using the clock, an alarm signal will be output from the alarm signal output terminal A of the clock LSI 7 for one hour at the set time. This alarm signal turns on the radio tape recorder driving switching circuit (SC) and drives the radio receiving circuit 33. Also, turn the alarm switch 4 to the OFF terminal (OFF).
At the same time, the first and second changeover switches 3,
6 to the sleep timer terminal S, the clock LSI 7
The switching circuit (SC) for driving the radio tape recorder is turned on and the radio receiving circuit 33 is operated only for one hour while the sleep signal is output from the sleep signal output terminal Sl of the device, and the power is automatically turned off after one hour. .

Now, as I am about to go to bed while listening to a radio broadcast, I connect the switching pieces of the first and second switching switches 3 and 6 to the sleep timer terminal S,
Connect the switch piece of the radio tape recorder switch 35 to the radio terminal R. When a tape recorder is set to record the radio program, for example, 50 minutes after the radio broadcast has started, the first and second power switches 2 and 29 are turned on and the radio broadcast is recorded onto the tape. .
Then, one hour after setting the sleep timer, that is, 10 minutes after starting recording, the sleep signal is no longer output from the clock LSI 7, but the DC power supply 1 switches between the first power switch 2 and the first resistor. 10 and the first diode 11 to the base of the first auxiliary switching transistor 13, the radio broadcast is recorded until the end of the tape.

As described above, according to the power supply device for a radio tape recorder with a clock according to this invention, the changeover switch selectively outputs the DC power supply and the sleep signal of the clock LSI to the radio. In a power supply device for a radio tape recorder with a clock, which supplies power to the switching circuit for driving the tape recorder and turns it on to operate the radio receiving circuit or the tape recorder driving circuit, the DC power supply and the sleep signal output terminal of the clock LSI are connected. Connect the sleep timer terminal of the connected changeover switch to the power switch, which is turned on by the tape recorder mechanism and turned off when the tape ends when the tape is running, through a resistor and a backflow prevention diode, and then connect the changeover switch of the changeover switch to the sleep timer terminal. By connecting to the input terminal of the switching circuit for driving a radio tape recorder, when trying to record a radio broadcast while the switching circuit for driving the radio tape is turned on by the sleep signal and the radio receiving circuit is operating, Since the switching circuit for driving the radio tape recorder is turned off and the power is turned off at the end of the sleep signal and the end of the tape due to tape running, whichever is later, the power is not cut off in the middle of a radio broadcast program. You can record up to the end of the tape. Furthermore, it is possible to solve the conventional problem that the power is cut off when the peach roller of the tape recorder mechanism and the capstan are in pressure contact with each other.

Further, by configuring the radio tape recorder driving switching circuit by connecting a plurality of switching transistors in parallel, voltage loss of the DC power supply applied to the amplifier section can be reduced.

Furthermore, by connecting a correction resistor to the base of each switching transistor in the switching circuit for driving a radio tape recorder, the collector of each switching transistor
It is possible to absorb variations in the voltage between emitters, and it is possible to simultaneously and completely turn on all switching transistors in a switching circuit for driving a radio tape recorder.

By connecting a capacitor for inrush current prevention between the input terminal of the switching circuit for driving a radio tape recorder and the ground, damage to the switching transistor due to the inflow of inrush current can be prevented. The present invention provides a power supply device for a clock radio tape recorder which has remarkable practical effects.

[Brief explanation of the drawing]

The drawing is a wiring diagram of one embodiment of a power supply device for a radio tape recorder with a clock according to the present invention. 1...DC power supply, 2...Power switch, 3, 6
...Selector switch, S...Sleep timer terminal, 7...Clock LSI, Sl...Sleep signal output terminal, 10...Resistor, 11...Diode,
19... Capacitor, 20, 23... Switching transistor, 21, 24... Correction resistor, SC... Switching circuit for driving a radio tape recorder, I... Input terminal of a switching circuit for driving a radio tape recorder, 31 . . . tape recorder drive circuit, 33 . . . radio reception circuit.

Claims (1)

[Claim for Utility Model Registration] A changeover switch selectively supplies a DC power source and a sleep signal of a clock LSI to a switching circuit for driving a radio tape recorder to turn it on, thereby operating a radio receiving circuit or a tape recorder driving circuit. In the power supply device for a radio tape recorder with a clock, the DC power supply and the sleep timer terminal of the changeover switch to which the sleep signal output terminal of the clock LSI is connected are turned on by the tape recorder mechanism and the tape A radio tape recorder with a clock, which is connected through a power switch, a resistor, and a backflow prevention diode, which turns off when the tape ends due to running, and a switching piece of the switch is connected to an input terminal of a switching circuit for driving the radio tape recorder. power supply. A power supply device for a radio tape recorder with a clock according to claim 1, wherein the switching circuit for driving the radio tape recorder is constructed by connecting a plurality of switching transistors in parallel. A power supply device for a radio tape recorder with a clock according to claims 1 and 2, wherein a correction resistor is connected to the base of each switching transistor of a switching circuit for driving a radio tape recorder. A power supply device for a radio tape recorder with a clock according to claims 1 to 3 of the utility model registration claim, which has a capacitor for preventing inrush current connected between the input terminal of a switching circuit for driving a radio tape recorder and the ground. .