Fan control circuit

Abstract

The utility model discloses a fan control circuit, and relates to the technical field of fan control. According to the main technical scheme, the circuit comprises a reference voltage module, a comparison voltage module, a thermistor R7, a comparison module and an on-off module, the output end of the thermistor R7 is connected with the input end of the comparison voltage module, and the thermistor R7 is used for adjusting the magnitude of comparison voltage according to the environment temperature of a fan cooling object; the input end of the comparison module is connected with the output end of the reference voltage module and the output end of the comparison voltage module; the output end of the comparison module is used for outputting a high level when the comparison voltage is smaller than the reference voltage; the input end of the on-off module is connected with the output end of the comparison module, and the output end of the on-off module is used for being connected with a fan; and the on-off module is in a conducting state when the comparison module outputs the high level. When a cooling object works and the environment temperature is low, the triode Q1F is in a disconnected state, and then the fan does not rotate, so that the purposes of reducing noise and prolonging the service life of the fan are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of fan control, in particular to a fan control circuit. Background Art

[0002] Traditional fans are mainly controlled by direct power supply, which produces high fan noise and causes the fan to be in a long working state, thus greatly shortening the fan's service life.

[0003] Existing stepless speed-adjustable fans are primarily controlled by a CPU / MCU, enabling smooth, continuous adjustment of fan speed, effectively reducing fan noise. However, these fans remain operational regardless of low or high temperatures, significantly shortening their lifespan. Utility Model Content

[0004] The utility model aims to provide a fan control circuit, which solves the problem that the existing stepless speed regulating fan is in a working state regardless of low temperature environment or high temperature environment, which greatly shortens the service life of the fan.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A fan control circuit includes a reference voltage module, a comparison voltage module, a thermistor R7, a comparison module, and an on-off module, wherein the input end of the reference voltage module is connected to an input power supply, and the output end of the reference voltage module is used to output a reference voltage; the input end of the comparison voltage module is connected to an input power supply, and the output end of the comparison voltage module is used to output a comparison voltage; the output end of the thermistor R7 is connected to the input end of the comparison voltage module, and the thermistor R7 is used to adjust the magnitude of the comparison voltage according to the ambient temperature of an object to be cooled by the fan; the input end of the comparison module is connected to both the output end of the reference voltage module and the output end of the comparison voltage module; the output end of the comparison module is used to output a high level when the comparison voltage is less than the reference voltage; the input end of the on-off module is connected to the output end of the comparison module, and the output end of the on-off module is used to connect to a fan; wherein the on-off module is in an on state when the comparison module outputs a high level.

[0007] A further technical solution is: the reference voltage module includes a resistor R1F and a resistor R2F; one end of the resistor R1F is used to connect to the input power supply; the other end of the resistor R1F is connected to one end of the resistor R2F and the input end of the comparison module; the other end of the resistor R2F is grounded.

[0008] A further technical solution is: the comparison voltage module includes a resistor R3F, a resistor R5F and a capacitor C1F; one end of the resistor R5F is used to connect to the input power supply; the other end of the resistor R5F is connected to one end of the resistor R3F, one end of the thermistor R7F, one end of the capacitor C1F, and the input end of the comparison module; the other end of the resistor R3, the other end of the thermistor R7F, and the other end of the capacitor C1F are all grounded.

[0009] A further technical solution is: the comparison module includes an operational amplifier U1A, a resistor R4F and a resistor R6F; pin 3 of the operational amplifier U1A is connected to the other end of the resistor R1F; pin 2 of the operational amplifier is connected to one end of the resistor R4F and one end of the resistor R6F; the other end of the resistor R4F is connected to the other end of the resistor R5F; pin 1 of the operational amplifier is connected to the other end of the resistor R6F and the input end of the on-off module.

[0010] A further technical solution is: the on-off module includes a transistor Q1F, a resistor R8F, a resistor R9F, a resistor R10F, a capacitor C92 and an electrolytic capacitor C91; one end of the resistor R8F is connected to pin 1 of the operational amplifier U1A; the other end of the resistor R8F is connected to the base of the transistor Q1F and one end of the resistor R10F; the emitter of the transistor Q1F, the other end of the resistor R10F and one end of the resistor R9F are all grounded; the collector of the transistor Q1F, the negative electrode of the electrolytic capacitor C91, one end of the capacitor C92 and the other end of the resistor R9F are all used to be connected to the fan; the positive electrode of the electrolytic capacitor C91 and the other end of the capacitor C92 are both used to be connected to the input power supply, and the positive electrode of the electrolytic capacitor C91 and the other end of the capacitor C92 are both used to be connected to the fan.

[0011] A further technical solution is: when the ambient temperature of the fan-cooled object is greater than a preset temperature, the comparison voltage is less than the reference voltage.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] When the ambient temperature of the cooling object is low, the transistor Q1F is in the off state, and the fan stops rotating, thereby achieving the purpose of reducing noise and increasing the practical life of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is an electrical block diagram of a fan control circuit in this embodiment;

[0015] Figure 2 FIG. 4 is a circuit structure topology diagram of a fan control circuit in this embodiment.

[0016] Markings and corresponding parts names in the accompanying drawings:

[0017] 100-reference voltage module; 200-comparison voltage module; 300-comparison module; 400-on / off module. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings.

[0019] Example

[0020] This embodiment provides a fan control circuit, such as Figure 1 As shown, the circuit comprises a reference voltage module 100, a comparison voltage module 200, a thermistor R7, a comparison module 300 and an on-off module 400. The input end of the reference voltage module 100 is used to be connected to an input power supply, and the output end of the reference voltage module 100 is used to output a reference voltage; the input end of the comparison voltage module 200 is used to be connected to an input power supply, and the output end of the comparison voltage module 200 is used to output a comparison voltage; the output end of the thermistor R7 is connected to the input end of the comparison voltage module 200, and the thermistor R7 is used to switch on and off according to the fan cooling The size of the comparison voltage is adjusted according to the ambient temperature of the cooling object; the input end of the comparison module 300 is connected to the output end of the reference voltage module 100 and the output end of the comparison voltage module 200; the output end of the comparison module 300 is used to output a high level when the comparison voltage is less than the reference voltage; the input end of the on-off module 400 is connected to the output end of the comparison module 300, and the output end of the on-off module 400 is used to be connected to the fan; wherein, the on-off module 400 is in the on state when the comparison module 300 outputs a high level.

[0021] like Figure 2 As shown, in this embodiment, the reference voltage module 100 includes a resistor R1F and a resistor R2F; one end of the resistor R1F is used to connect to the input power supply; the other end of the resistor R1F is connected to one end of the resistor R2F and the input end of the comparison module 300; and the other end of the resistor R2F is grounded.

[0022] like Figure 2 As shown, in this embodiment, the comparison voltage module 200 includes a resistor R3F, a resistor R5F and a capacitor C1F; one end of the resistor R5F is used to connect to the input power supply; the other end of the resistor R5F is connected to one end of the resistor R3F, one end of the thermistor R7F, one end of the capacitor C1F, and the input end of the comparison module 300; the other end of the resistor R3, the other end of the thermistor R7F, and the other end of the capacitor C1F are all grounded.

[0023] like Figure 2 As shown, in this embodiment, the comparison module 300 includes an operational amplifier U1A, a resistor R4F and a resistor R6F; pin 3 of the operational amplifier U1A is connected to the other end of the resistor R1F; pin 2 of the operational amplifier is connected to one end of the resistor R4F and one end of the resistor R6F; the other end of the resistor R4F is connected to the other end of the resistor R5F; pin 1 of the operational amplifier is connected to the other end of the resistor R6F and the input end of the on-off module 400.

[0024] like Figure 2 As shown, in this embodiment, the on-off module 400 includes a transistor Q1F, a resistor R8F, a resistor R9F, a resistor R10F, a capacitor C92 and an electrolytic capacitor C91; one end of the resistor R8F is connected to pin 1 of the operational amplifier U1A; the other end of the resistor R8F is connected to the base of the transistor Q1F and one end of the resistor R10F; the emitter of the transistor Q1F, the other end of the resistor R10F, and one end of the resistor R9F are all grounded; the collector of the transistor Q1F, the negative electrode of the electrolytic capacitor C91, one end of the capacitor C92, and the other end of the resistor R9F are all used to connect to the fan; the positive electrode of the electrolytic capacitor C91 and the other end of the capacitor C92 are both used to connect to the input power supply, and the positive electrode of the electrolytic capacitor C91 and the other end of the capacitor C92 are both used to connect to the fan.

[0025] like Figure 2 As shown, in this embodiment, when the ambient temperature of the fan-cooled object is greater than a preset temperature, the comparison voltage is less than the reference voltage.

[0026] The preset temperature may be preset according to the ambient temperature of the fan-cooled object when the fan is working normally, for example, it may be any value between 20°C and 35°C.

[0027] The working principle of a fan control circuit in this embodiment is as follows:

[0028] During operation, the reference voltage output by the reference voltage module 100 acts on pin 3 of the operational amplifier U1A (the positive input terminal of the operational amplifier U1A); the comparison voltage output by the comparison voltage module 200 acts on pin 2 of the operational amplifier U1A (the negative input terminal of the operational amplifier U1A).

[0029] For example, when the preset temperature is 30°C.

[0030] If the ambient temperature of the object being cooled by the fan is less than or equal to 30°C, the resistance of thermistor R7F is large, the comparison voltage at the reverse input of operational amplifier U1A is greater than or equal to the reference voltage at the forward input of operational amplifier U1A, pin 1 of operational amplifier U1A outputs a low level, transistor Q1F is in the off state, and the fan does not rotate.

[0031] As the ambient temperature of the fan-cooled object gradually increases, the resistance of thermistor R7F gradually decreases, and the comparison voltage at the inverting input terminal of operational amplifier U1A gradually decreases.

[0032] When the ambient temperature of the fan-cooled object gradually rises to greater than 30°C, the comparison voltage at the reverse input terminal of the operational amplifier U1A is less than the reference voltage at the forward input terminal of the operational amplifier U1A. Pin 1 of the operational amplifier U1A outputs a high level, transistor Q1F is in the on state, and the fan rotates.

[0033] As the ambient temperature of the fan-cooled object gradually increases, the ratio of the output of operational amplifier U1A is controlled by the ratio of resistors R6F and R4F, causing the voltage output from pin 1 of operational amplifier U1A to gradually increase, thereby gradually increasing the operating power of the fan.

[0034] When the ambient temperature of the cooling object is low, the transistor Q1F is in the off state, and the fan stops rotating, thereby achieving the purpose of reducing noise and increasing the practical life of the fan.

[0035] Although the present invention has been described herein with reference to a number of illustrative embodiments thereof, it will be understood that numerous other modifications and implementations may be devised by those skilled in the art that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure, the drawings, and the claims, numerous variations and improvements may be made to the components and / or arrangement of the subject combination arrangement. In addition to variations and improvements to the components and / or arrangement, other uses will also be apparent to those skilled in the art.

Claims

1. A fan control circuit, characterized in that: include: A reference voltage module (100), wherein an input end of the reference voltage module (100) is used to be connected to an input power supply, and an output end of the reference voltage module (100) is used to output a reference voltage; A comparison voltage module (200), wherein an input end of the comparison voltage module (200) is used to be connected to an input power supply, and an output end of the comparison voltage module (200) is used to output a comparison voltage; a thermistor R7, wherein the output end of the thermistor R7 is connected to the input end of the comparison voltage module (200), and the thermistor R7 is used to adjust the magnitude of the comparison voltage according to the ambient temperature of the fan-cooled object; A comparison module (300), wherein the input end of the comparison module (300) is connected to the output end of the reference voltage module (100) and the output end of the comparison voltage module (200); the output end of the comparison module (300) is used to output a high level when the comparison voltage is less than the reference voltage; an on-off module (400), wherein an input end of the on-off module (400) is connected to an output end of the comparison module (300), and an output end of the on-off module (400) is used to be connected to a fan; Wherein, the on-off module (400) is in an on state when the comparison module (300) outputs a high level.

2. The fan control circuit according to claim 1, wherein: The reference voltage module (100) comprises a resistor R1F and a resistor R2F; One end of the resistor R1 F is used to connect to the input power supply; The other end of the resistor R1F is connected to one end of the resistor R2F and the input end of the comparison module (300); The other end of the resistor R2F is grounded.

3. The fan control circuit according to claim 2, wherein: The comparison voltage module (200) comprises a resistor R3F, a resistor R5F and a capacitor C1F; One end of the resistor R5F is used to connect to the input power supply; The other end of the resistor R5F is connected to one end of the resistor R3F, one end of the thermistor R7F, one end of the capacitor C1F, and the input end of the comparison module (300); The other end of the resistor R3, the other end of the thermistor R7F, and the other end of the capacitor C1F are all grounded.

4. The fan control circuit according to claim 3, wherein: The comparison module (300) includes an operational amplifier U1A, a resistor R4F, and a resistor R6F; Pin 3 of the operational amplifier U1A is connected to the other end of the resistor R1F; Pin 2 of the operational amplifier is connected to one end of the resistor R4F and one end of the resistor R6F; The other end of the resistor R4F is connected to the other end of the resistor R5F; Pin 1 of the operational amplifier is connected to the other end of the resistor R6F and the input end of the on-off module (400).

5. The fan control circuit according to claim 4, wherein: The on-off module (400) comprises a transistor Q1F, a resistor R8F, a resistor R9F, a resistor R10F, a capacitor C92 and an electrolytic capacitor C91; One end of the resistor R8F is connected to pin 1 of the operational amplifier U1A; The other end of the resistor R8F is connected to the base of the transistor Q1F and one end of the resistor R10F; The emitter of the transistor Q1F, the other end of the resistor R10F, and one end of the resistor R9F are all grounded; The collector of the transistor Q1 F, the negative electrode of the electrolytic capacitor C91, one end of the capacitor C92, and the other end of the resistor R9F are all used to connect to the fan; The positive electrode of the electrolytic capacitor C91 and the other end of the capacitor C92 are both used to connect to the input power supply, and the positive electrode of the electrolytic capacitor C91 and the other end of the capacitor C92 are both used to connect to the fan.

6. The fan control circuit according to claim 1, wherein: When the ambient temperature of the fan-cooled object is greater than a preset temperature, the comparison voltage is less than the reference voltage.

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