JPS5918496Y2 - voltage stabilizer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a voltage stabilizing device, and an object of the present invention is to provide a device that can obtain a high voltage even when the power supply voltage drops when using a DC power source.

FIG. 1 shows a conventional example of this type of device.

In FIG. 1, reference numeral 1 denotes a transformer to which an AC power supply voltage is applied, and its output is converted into DC by a diode 2 and a capacitor 3 and applied to a terminal 4a of a switch 4.

A voltage from a DC power supply 5 is applied to the terminal 4b of the switch 4, and the switch 4 is configured to switch between AC and DC using a movable contact piece 4C.

The movable contact piece 4C is connected to the collector of a transistor 12 constituting a voltage stabilizing circuit.
The emitter of is connected to the load 13.

Further, the collector of the transistor 12 is also connected to a load 14 via a reverse current prevention diode 6.

7 is a protection resistor for the transistor 12, 8 is a base bias resistor for the transistor 12, 9 is a Zener diode for maintaining a constant voltage, and 10 is a reverse current prevention diode that protects the circuit when the DC power supply 5 is connected with reverse polarity. , 11
is a filter capacitor.

The load 13 is a load that particularly requires a stabilized voltage, and the load 14 is a load whose voltage may fluctuate to some extent.

In this circuit, transistor 12 has a switch connected to terminal 4.
A, 4B operate in the same way whether they are connected to AC or DC, but when the voltage of DC power source 5 (for example, a storage battery) decreases, the output voltage of transistor 12 decreases and the load 13 no longer works.

The present invention provides a device that improves these drawbacks, and one embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a circuit showing an embodiment of the present invention, and the same parts as in FIG. 1 are given the same numbers and explanations are omitted, and the features of the present invention will be explained below.

As shown in FIG. 2, the output voltage of the DC power supply 5 passes through a diode 17 provided to prevent the base current of the transistor 12 from flowing when the AC power supply is used, passes through a filter capacitor 19, a resistor 18, and then reaches the base of the transistor 12. is applied to

Further, the output voltage of this DC power supply 5 is applied to the terminal 4a of the switch 4 via a diode 16 and a resistor 15 that prevent reverse current when the DC power supply 5 is connected with reverse polarity.

Here, when connecting the movable contact piece 4C of the switch 4 to the terminal 4b side and operating the surface loads 13 and 14 with the output of the DC power supply 5, the base of the transistor 12 is connected via the resistor 8 as before. At the same time as the base voltage is applied, the base voltage is applied via the diode 17 and the resistor 18.

Therefore, when the voltage of the DC power supply 5 is sufficiently high and the Zener diode 9 conducts and becomes a constant voltage, the transistor 1
The base voltage of 2 is the same as when using an AC power supply.

On the other hand, when the voltage of the DC power supply 5 decreases and the voltage across the Zener diode 9 becomes less than the Zener voltage, the Zener diode 9 no longer performs the constant voltage generation operation.
The base voltage of transistor 12 begins to drop.

In this state, the voltage from the DC power supply 5 is applied to the base of the transistor 12 not only through the resistor 8 but also through the resistor 18, and in effect, the resistors 8 and 18 are connected in parallel. Therefore, the base voltage when the DC power supply voltage drops is higher than that in the conventional circuit where voltage is applied only through the resistor 8.

Therefore, the voltage drop between the collector and emitter of the transistor 12 can be reduced, and the high voltage necessary for the load 13 can be stably supplied.

Moreover, since the base potential has become high, the filtering effect is insufficient with the capacitor 11 alone, but since the capacitor 19 is added, a sufficient filtering effect can be obtained.

When using a DC power supply, the load 14 includes a resistor 15 and a diode 1.
6, the voltage is lowered and supplied to reduce the amount of voltage change due to fluctuations in the load 14 (for example, fluctuations in the audio output circuit), so that the fluctuations are less likely to affect the load 13.

Note that the capacitors 11 and 19 are non-polar electrolytic capacitors so that no current flows when the DC power supply 5 is reversely connected.

Note that the AC power source and the DC power source do not exist at the same time.

As described above, according to the present invention, a higher base voltage can be supplied to the base of the transistor of the voltage stabilizing circuit when using a DC power supply than when using an AC power supply, so the voltage of the DC power supply decreases to some extent. The load also operates normally.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional voltage stabilizing device, and FIG. 2 is a circuit diagram of a voltage stabilizing device according to an embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] a switch capable of applying voltage to a load by switching between an AC power supply and a DC power supply; a voltage stabilizing means connected between the switch and the load; a transistor constituting the voltage stabilizing means; a first base resistor connected between the switch and the base of the transistor so as to apply the AC power supply voltage to the base of the transistor when the switch is connected to the power supply side; The first transistor applies the DC power supply voltage to the base of the transistor when connected to the
and a second base resistor connected in parallel to the first base resistor.