JPH054013Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a stabilized power supply circuit device for, for example, in-vehicle equipment.

(Prior art) Generally, tape recorders, tuners, etc.
When used as in-vehicle equipment, a stabilized power supply circuit device with a small output current is used to minimize consumption of in-vehicle power supply. 2. Description of the Related Art Conventionally, as this type of vehicle-mounted stabilized power supply circuit device, one shown in FIG. 1, for example, is known. This removes the noise component of the input current given from the power supply +B by using the choke coil L that acts as a low-pass filter and the power supply noise removal capacitor C1, and then closes the power supply on/off switch SW to reduce the ripple of this input current. Min, power supply ripple smoothing capacitor C2
After bypassing it to the ground side and removing it, the smoothed DC output is supplied to a power amplifier circuit (not shown) connected to the terminal T, while
By applying this DC output as a base voltage to the base of a stabilized transistor Q included in the stabilized power supply circuit 1, and controlling the base voltage of the transistor Q according to the power supply voltage, the emitter of the transistor Q is controlled. The stabilized power output is supplied from the power source to a load such as a tuner (not shown). For this purpose, this stabilized power supply circuit 1 includes a ripple removal capacitor C3 between the base of the transistor Q and the ground.
A Zener diode D2 and a noise removal capacitor C4 of the Zener diode D2 are provided in parallel, a smoothing capacitor C5 is provided between the emitter of the transistor Q and the ground, and a bias resistor is provided between the base and collector of the transistor Q. Inserting R. In the figure, F is a fuse, and D1 is a diode for preventing damage to the equipment due to reverse connection of the power cord. By the way, the problem with this is that the power output to be supplied to the power amplifier is extracted from between the power supply choke coil L and the collector of the stabilizing transistor Q. That is, in such a connection state, there is no problem in adopting it for a power amplifier circuit with a small output or standard output, but if a power amplifier circuit with a large output is connected, the volume of the power amplifier circuit can be increased, for example. When the input level of the power amplifier circuit is increased, the power supply current increases significantly, causing a significant drop in the power supply voltage at the power supply choke coil L section, and as a result, the collector voltage of the stabilizing transistor Q becomes lower than the base voltage. As a result, the operation of the stabilized power supply circuit 1 becomes unstable. In order to eliminate this problem, it is necessary to maintain the collector voltage of the stabilizing transistor Q at a higher voltage than the base voltage at all times, but in the conventional device described above, the only solution is to set the inductance of the power supply chain coil L to a small value. I was bored. However, if a coil with a small inductance is employed as the chiyoke coil L, the power supply noise removing effect of the chiyoke coil L is significantly reduced, making it impossible to obtain the required power supply noise removing effect.

(Purpose) The present invention was made in order to eliminate the above-mentioned conventional problems, and it maintains the power supply noise removal effect of the power supply choke coil at least to the same level as the conventional device, and it The purpose is to provide a stabilized power supply circuit device in which the stabilized power supply circuit operates stably even when the circuit is connected, and in order to achieve this purpose,
It is structured as follows.

That is, a stabilized power supply circuit having a stabilizing transistor is provided, the base of this stabilizing transistor is connected to the power supply side via a power source coil, and the collector thereof is connected to a tap provided on the power source source coil. and controlling the base voltage of the stabilizing transistor according to the power supply voltage from the power supply side,
A stabilized power output is supplied from the emitter.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings. FIG. 2 is an electrical circuit diagram of the stabilized power supply circuit device of this embodiment. Components common or corresponding to those in FIG. 1 are given the same reference numerals. In FIG. 2, this stabilized power supply circuit device includes a power supply +B
After removing the noise from the input current given from the input current by the power supply choke coil L, which acts as a low-pass filter, and the power supply noise removal capacitor C1, the power supply on/off switch is turned on.
By closing the SW, this DC output is supplied to a power amplifier circuit (not shown), and the output is stabilized by the stabilized power supply circuit 1 and supplied to a load such as a tuner. .
The power source coil L is a coil having sufficient inductance to remove power supply noise, and the noise is dropped to the ground side through the power source coil L and capacitor C1. Further, F is a fuse, and D1 is a diode for preventing damage to the equipment due to reverse connection of the power cord.

Next, when the power supply on/off switch SW is closed, the power supply input from which noise has been removed is smoothed by bypassing the ripple component of the input current to the ground side by the power supply ripple smoothing capacitor C2. be done. The smoothed output thus obtained is supplied to a high output power amplifier circuit.

The stabilized power supply circuit 1 includes a stabilized transistor Q.
, and a ripple removal capacitor C3 and a Zener diode D2 are connected between its base and the ground.
and Zener diode D2 noise removal capacitor C4 are inserted in parallel, and the capacitor C4 is inserted between the emitter and the ground.
5, and a Baoas resistor R is inserted between its base and the power supply chiyoke coil L, and by passing a Zener current through the Zener diode D2, a specified Zener voltage is obtained, the output voltage is stabilized, and the output voltage is stabilized. A stabilized power output is supplied from the emitter of transistor Q to a load such as a tuner.

In the above configuration, the feature of the present invention is that a tap is provided between the power supply choke coil L having a large inductance value, and this tap is directly connected to the collector of the stabilizing transistor Q of the stabilized power supply circuit 1. , by constantly supplying the power output with the voltage dropped by the required inductance from the chiyoke coil L to the collector of the transistor Q, the collector voltage is not affected by changes in the output of the power amplifier and is always higher than the base voltage. The point is that it can be maintained. Therefore, even if the power supply current flowing through the power amplifier circuit is increased by increasing the input level of the power amplifier circuit, such as by increasing the volume of the power amplifier circuit, the collector voltage of the stabilizing transistor Q will always be higher than the base voltage. A high voltage is maintained, and as a result, the operation of the stabilized power supply circuit 1 is maintained in a stable state. Further, the inductance of the entire power source coil L is involved in the noise of the power source input, so that the power source noise removal effect of the power source coil L is not hindered.

(Effects) As described below, according to the present invention, a tap is provided on the power source choke coil interposed between the stabilizing transistor and the power supply side, and this tap is connected to the collector of the stabilizing transistor. Therefore, even if a high-output power amplifier circuit is connected, the collector voltage of the stabilizing transistor can be maintained at a voltage higher than the base voltage at all times without being affected by changes in the output of the power amplifier circuit. Therefore, the stabilized power supply circuit can always operate in a stable state. Further, since a coil with a large inductance can be used as the power source coil, it has the advantage that noise in the power source input can be sufficiently removed.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit diagram showing an example of a conventional stabilized power supply circuit device. FIG. 2 is an electrical circuit diagram showing an embodiment of the power supply stabilizing circuit device according to the present invention. 1 is a stabilizing power supply circuit, L is a power supply choke coil, and Q is a stabilizing transistor.

Claims (1)

[Scope of utility model claims] A stabilized power supply circuit having a stabilizing transistor is provided, the base of the stabilizing transistor is connected to the power supply side via a power supply choke coil, and the collector thereof is connected to a tap provided on the power supply choke coil, A stabilized power supply circuit device characterized in that a stabilized power output is supplied from an emitter of the stabilized transistor by controlling a base voltage of the stabilized transistor according to a power supply voltage from the power supply side.