Fan speed testing system and method

1. Technical Field

The present disclosure relates to testing systems and methods, especially to a testing system and method for testing fan speed.

2. Description of Related Art

After computers are produced, quality tests are required. One of the tests is testing the fans of the computers. A conventional method to test the speed of the fans is using a tachometer. However, the conventional method requires opening the computer and manually positioning the tachometer close to the fan, which wastes time and manpower, and the tachometer is expensive.

FIG. 1 is a block view of a fan speed testing system in accordance with an embodiment.

FIG. 2 is a circuit diagram of a voltage stabling circuit of the fan speed testing system in accordance with an embodiment.

FIG. 3 is a circuit diagram of a frequency collecting and wave processing circuit of a fan speed testing system in accordance with an embodiment.

FIG. 4 is a circuit diagram of a converting and displaying circuit of a fan speed testing system in accordance with an embodiment.

The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.

Referring to FIG. 1 , a fan speed testing system 100 includes a power source 10 , a collecting module 30 , a processing module 50 connected to the collecting module 30 , a converting module 70 connected to the processing module 50 , and a displaying module 90 connected to the converting module 70 .

Referring to FIG. 2 , a voltage stabling circuit 200 is used in the power source 10 . The voltage stabling circuit 200 includes a power input terminal 201 and a voltage stabling chip 203 . In one embodiment, the voltage stabling chip 203 is a LM7805 chip. An input pin IN of the voltage stabling chip 203 is connected to the power input terminal 201 by a diode D 1 and a power controlling switch S 1 , and connected to ground by a capacitor C 1 . A positive terminal of the diode D 1 is connected to a +9V voltage source. A negative terminal of the diode D 1 is connected to ground by a resistor R 1 and a light-emitting diode (LED) D 2 . An output pin OUT of the voltage stabling chip 203 is connected to the input pin IN by a diode D 3 , and connected to ground by a capacitor C 2 . The input pin IN is connected to ground by a capacitor C 3 . The output pin OUT is connected to ground by a capacitor C 4 , and also connected to ground by a resistor R 2 and a LED D 4 . A ground pin GND of the voltage stabling chip 203 is connected to ground. The voltage stabling chip 203 is used for converting +9V voltage at the input pin IN to +5V voltage at the output pin. The voltage stabling circuit 200 provides a +9V voltage source and a +5V voltage source. Wherein the +9V voltage source provides power to the collecting module 30 and the processing module 50 , and the +5V voltage source provides power to the converting module 70 and the displaying module 90 .

Referring to FIG. 3 , a frequency collecting and wave processing circuit 300 is used in the collecting module 30 and the processing module 50 . The frequency collecting and wave processing circuit 300 includes a reflecting infrared sensor 301 , a first comparator 303 connected to the reflecting infrared sensor 301 , and a second comparator 305 connected to the first comparator 303 .

In one embodiment, the reflecting infrared sensor 301 is a ST178 chip. The reflecting infrared sensor 301 includes a LED D 5 and a phototransistor Q 1 . A positive terminal of the LED D 5 is connected to the +9V voltage source of the voltage stabling circuit 200 by a resistor R 3 , and a negative terminal of the LED D 5 is connected to ground. A collector of the phototransistor Q 1 is connected to the +9V voltage source by a resistor R 4 , and an emitter of the phototransistor Q 1 is connected to ground. A positive input terminal of the first comparator 303 is connected to the collector of the phototransistor Q 1 by a resistor R 5 . A negative input terminal of the first comparator 303 is connected to a wiper of a potentiometer R 6 . A terminal of the potentiometer R 6 is connected to the +9V voltage source, and another terminal of the potentiometer R 6 is connected to ground. A power terminal of the first comparator 303 is connected to the +9V voltage source, and respectively connected to ground by capacitor C 5 and capacitor C 6 . A ground terminal of the first comparator 303 is connected to ground. An output terminal of the first comparator 303 is connected to a terminal of a potentiometer R 7 . A wiper of the potentiometer R 7 is connected to a positive input terminal of the second comparator 305 . Another terminal of potentiometer R 7 is connected to ground. A negative input terminal of the second comparator 305 is connected to an output terminal I/O of the second comparator 305 . A power terminal of the second comparator 305 is connected to the +9V voltage source, and a ground terminal of the first comparator 303 is connected to ground.

Referring to FIG. 4 , a converting and displaying circuit 700 is applied in the converting module 70 and the displaying module 90 . The converting and displaying circuit 700 is used for receiving a pulse signal sent from the frequency collecting and wave processing circuit 300 , converting the pulse signal to a fan speed data, and displaying the fan speed data. The converting and displaying circuit 700 includes a converting chip 701 and a displaying circuit 703 . In one embodiment, the converting chip 701 is MCS-51 MCU. A power pin VCC of the converting chip 701 is connected to the +5V voltage source of the voltage stabling circuit 200 , and connected to ground. A capacitor C 7 and a capacitor C 8 are connected in parallel. A ground pin VSS is connected to ground. Two clock pins XTAL 1 , XTAL 2 are connected to a clock circuit 705 . The clock circuit 705 includes a crystal oscillator Y 1 and two capacitors C 9 and C 10 . The crystal oscillator Y 1 is connected between the clock pins XTAL 1 , and XTAL 2 . The clock pin XTAL 1 is connected to ground by the capacitor C 9 , and the clock pin XTAL 2 is connected to ground by the capacitor C 10 . A resetting pin RST of the converting chip 701 is connected to a control circuit 707 . The control circuit 707 includes a switch K 1 . The resetting pin RST is connected to ground by resistor R 8 and resistor R 9 . One terminal of the resistor R 8 is connected to the +5V voltage source by the switch K 1 , and another terminal of the resistor R 8 is connected to the +5V voltage source by a capacitor C 11 . The displaying circuit 703 includes four seven-segment displays. Pins P 2 . 0 -P 2 . 7 are respectively connected to pins a, b, c, d, e, f, g, and DP of the four seven-segment displays. Pins 1 .- 1 . 7 are used for controlling the four seven-segment displays to be turned on or off. A Pin P 3 . 2 is connected to the output terminal I/O of the frequency collecting and wave processing circuit 300 .

Referring to FIGS. 1 to 4 , the working principle of the fan speed testing system 100 is described below.

A label with an identifiable color is attached on a vane or blade of a testing fan. In one embodiment, the label is a white strip and the testing fan is black. When the fan speed testing system 100 is operational, light reflected off the label enables the phototransistor Q 1 to be turned on if light from the LED D 5 reflects off of the label. At this time, the phototransistor Q 1 is in a first state. The phototransistor Q 1 is turned off if light from the LED D 5 reflects off of the other part of the testing fan. At this time, the phototransistor Q 1 is in a second state. The label rotates when the vane or blade of the testing fan rotates, thereby the phototransistor Q 1 is turned on intermittently, which makes the reflecting infrared sensor 301 produce a pulse signal. The pulse signal is amplified and adjusted by the first comparator 303 and the second comparator 305 to be a standard square wave. The square wave is delivered to the pin P 3 . 2 of the converting chip 701 . The converting chip 701 collects conversion times when the level falls from high to low in the square wave, which means the testing fan rotate one time. The converting chip 701 can calculate the fan speed data of the testing fan during a given period of time. The converting chip 701 delivers the fan speed data to displaying circuit 703 and the display circuit 703 displays the fan speed data.

It is to be understood, however, that even though numerous characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.