CN203883549U - AC/DC automatic switch - Google Patents

Abstract

The AC-DC automatic switcher of the utility model includes an AC input stage and a DC power supply; it also includes a rectification input stage and an AC-DC switching stage, and the rectification input stage is composed of a first capacitor, a second capacitor, a Zener diode and a first Composed of rectifier diodes, the AC-DC switching stage is composed of a first transistor, a second transistor, a first resistor, a second resistor, and a second rectifier diode, and the DC power supply is connected to the ground wire and the second transistor Between the collectors, the working load is connected between the ground and the emitter of the second triode. The utility model can automatically detect and switch to the DC power supply mode when the AC mains input power is cut off. It has a simple structure and does not need various integrated circuit chips required by traditional emergency equipment. The conversion function is suitable for mass promotion and use in the case of low-precision power supply.

Description

AC-DC automatic switcher

technical field

The utility model relates to the field of electronic circuits, in particular to an AC/DC automatic switcher. the

Background technique

The monitoring of the AC power grid or other equipment is usually powered by 220V AC mains power supply. It is convenient and easy to use AC mains power supply, and the power supply has strong driving ability. In particular, it is necessary for the equipment related to grid maintenance to work normally, such as alarm system, emergency lighting system and some maintenance equipment. the

Although there are emergency equipment on the market that can still work in the state of AC power failure, most of them use high-precision DC power supply or batteries and supporting charging circuits. The equipment is expensive and has poor versatility, so it is not suitable for large-scale promotion and use. the

Utility model content

In order to overcome the technical defects of expensive equipment and poor versatility in the prior art, the utility model discloses an AC/DC automatic switcher. the

The AC-DC automatic switcher of the utility model includes an AC input stage and a DC power supply; it also includes a rectification input stage and an AC-DC switching stage, and the rectification input stage is composed of a first capacitor, a second capacitor, a Zener diode and a first Composed of rectifier diodes, the first capacitor is connected between the input terminal of the live line and the anode of the first rectifier diode, the Zener diode is connected between the anode of the first rectifier diode and the input terminal of the neutral line, and the second capacitor is connected between Between the cathode of the first rectifier diode and the input end of the neutral line; the AC-DC switching stage is composed of a first transistor, a second transistor, a first resistor, a second resistor, and a second rectifier diode, and the first The base and the collector of the triode are respectively connected to one end of the first resistor and the second resistor, and the other ends of the first resistor and the second resistor are respectively connected to the positive and negative poles of the second rectifying diode; the positive pole of the second rectifying diode and the emitter of the first triode are respectively connected to the cathode of the first rectifier diode and the input terminal of the neutral line; the collector of the first triode is connected to the base of the second triode, and the collector of the second triode Connect the cathode of the second rectifier diode; the base of the first triode is also connected to the emitter of the second triode; the DC power supply is connected between the ground wire and the collector of the second triode, and the working load Connect between ground and the emitter of the second triode. the

Preferably, a fuse resistor is connected in series at the live line input terminal and/or the input neutral line terminal. the

Preferably, a light emitting diode is also connected between the collector of the second triode and the DC power supply. the

Specifically, the models of the first rectifying diode and the second rectifying diode are IN4001. the

The AC-DC automatic switcher of the utility model can automatically detect and switch to the DC power supply mode when the AC mains input power is cut off, the structure is simple, and there is no need for various integrated circuit chips required by traditional emergency equipment, and only a small number is required The separate device can complete the AC-DC conversion function, which is suitable for mass promotion and use in the case of low-precision power supply. the

Description of drawings

Fig. 1 is a kind of specific embodiment schematic diagram of the utility model;

The marks in the drawings and the names of corresponding parts: RF-fuse resistor, C1-first capacitor, C2-second capacitor, L-fire wire input terminal, N-neutral line input terminal, VS-zener diode VD1-second One rectifier diode, VD2-second rectifier diode, VD3-light-emitting diode, R1-first resistor, R2-second resistor, RL-working load, VT1-first triode, VT2-second triode, DC -DC power supply.

Detailed ways

The utility model will be further described in detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto. the

The AC-DC automatic switcher includes an AC input stage and a DC power supply; it also includes a rectification input stage and an AC-DC switching stage, and the rectification input stage is composed of a first capacitor C1, a second capacitor C2, a Zener diode VS and a first rectifier diode Composed of D1, the first capacitor is connected between the live line input terminal L and the anode of the first rectifier diode, the Zener diode is connected between the anode of the first rectifier diode and the input terminal of the neutral line, and the second capacitor is connected between Between the cathode of the first rectifier diode and the input terminal N of the neutral line;

The AC-DC switching stage is composed of a first transistor VT1, a second transistor VT2, a first resistor R1, a second resistor R2, and a second rectifier diode VD2. The base and collector of the first transistor are The electrodes are respectively connected to one end of the first resistor and the second resistor, and the other ends of the first resistor and the second resistor are respectively connected to the positive pole and the negative pole of the second rectifier diode; the positive pole of the second rectifier diode and the emitter of the first triode The poles are respectively connected to the negative pole of the first rectifying diode and the input end of the neutral line; the collector of the first triode is connected to the base of the second triode, and the collector of the second triode is connected to the negative pole of the second rectifying diode; The base of the first triode is also connected to the emitter of the second triode;

The DC power supply is connected between the ground wire and the collector of the second triode, and the working load is connected between the ground wire and the emitter of the second triode.

Input the power frequency 220V mains from the live wire input terminal and the neutral line input terminal of the AC input stage, and the AC voltage is stepped down by the first capacitor C1 and the Zener diode VS. Usually, the single step-down value of the Zener diode is 3-10V, and the voltage is stabilized. The voltage is determined by the working voltage of the workload. When a higher voltage is required, it can be realized by superimposing multiple Zener diodes. the

After stepping down, the AC negative voltage waveform is filtered through the first rectifier diode VD1 and the second capacitor C2, and a half-wave DC voltage with narrowed amplitude is obtained on the second capacitor C2, and the DC power is supplied to the working load RL through the first resistor R1 , because the base voltage of the first triode is much higher than the turn-on voltage, VT1 is turned on, which pulls down the base voltage of the second triode VT2, and at the same time, there is a voltage drop on the working load RL, causing the second triode VT2 to fail to conduct. Pass. the

When the AC mains power is cut off, the first triode VT1 changes from on to off, and the DC voltage of the DC power supply is applied to the second triode through the second resistor R2, so that the second triode is turned on, and the DC power supply DC The working load RL connected to its emitter is powered through the second triode. When the AC power is restored, VT1 is turned on, VT2 is turned off, and the workload continues to be powered by the AC power. A specific implementation method is: C1=1.5 microfarads, C2=100 microfarads, R1=5.1K, R2=1K, where high-voltage devices are seen, such as C1 needs to take a capacitor with a high withstand voltage value, the first rectifier diode, The second rectifier diode model can be cheap IN4001. the

Preferably, a fuse resistor RF is connected in series with the live line input terminal and/or the neutral line input terminal. The fuse resistor plays a role in high current fusing protection. A light-emitting diode can be connected to the collector branch of the second triode. When the AC mains power is cut off and the DC power is supplied, the light-emitting diode turns on and emits light to remind the AC mains power failure. the

As mentioned above, the utility model can be better realized. the

Claims (1)

1. alternating current-direct current automatic switchover device, comprises and exchanges input stage and DC power supply; It is characterized in that, also comprise rectification input stage and alternating current-direct current stage of switches, described rectification input stage is made up of the first electric capacity, the second electric capacity, voltage stabilizing didoe and the first rectifier diode, described the first electric capacity is connected between live wire input and the first rectifier diode positive pole, described voltage stabilizing didoe is connected between the first rectifier diode positive pole and zero line input, and described the second electric capacity is connected between the first rectifier diode negative pole and zero line input;

Described alternating current-direct current stage of switches is made up of the first triode, the second triode, the first resistance, the second resistance, the second rectifier diode, the base stage of described the first triode and collector electrode are connected respectively one end of the first resistance, the second resistance, and the other end of the first resistance, the second resistance connects respectively the positive and negative electrode of the second rectifier diode; The emitter of the positive pole of described the second rectifier diode and the first triode is connected respectively the first rectifier diode negative pole and zero line input; Described the first transistor collector connects the second transistor base, and the collector electrode of described the second triode connects the negative pole of the second rectifier diode; The base stage of described the first triode is also connected with the emitter of the second triode;

DC power supply is connected between ground wire and the collector electrode of the second triode, and operating load is connected between ground wire and the second transistor emitter.

2. alternating current-direct current automatic switchover device according to claim 1, is characterized in that, described live wire input and/or input zero line side are also in series with fuse resistor.

3. alternating current-direct current automatic switchover device according to claim 1, is characterized in that, between described the second transistor collector and DC power supply, is also connected with light-emitting diode.

4. alternating current-direct current automatic switchover device according to claim 1, is characterized in that, described the first rectifier diode, the second rectifier diode model are IN4001.