1. Technical Field
The present disclosure relates to test devices, and particularly to a test device which has an interface compatible with a computer and can test rotation speed of a fan.
2. Description of Related Art
One test device used in a laboratory for testing rotation speed of fans has a very complicated structure. An additional communication interface is needed to connect the test device with a computer. As a result of the additional interface, the communication between the test device and the computer is slow, and test efficiency of the test device is very low.
What is needed, therefore, is a fan rotation speed test device which can overcome the limitations described.
Referring to
Also referring to
Each fan has four pins 1-4. The pins 1 of the fans FAN1-FAN3 connect to the signal amplifying units U2-U4 respectively. The pins 2 of the fans FAN1-FAN3 connect to a 12-volt direct current power source. The pins 3 of the fans FAN1-FAN3 connect to ground. The pins 4 of the fans FAN1-FAN3 connect to pins GPIO3, GPIO4, OUT of the chip U1 respectively.
The signal amplifying units U2-U4 all have the same structure, so only the signal amplifying unit U2 is explained below for simplicity. The signal amplifying unit U2 includes a transistor Q1, four resistors R1-R4, and a capacitor C1. The resistor R4 is connected between the pin 1 of the fan FAN1 and a base B1 of the transistor Q1, and the resistor R4 has a 4.7 kilo-ohm resistance. A node N1 is formed between the resistor R4 and the pin 1 of the fan FAN1. The resistor R2 is connected between the node N1 and a 3-volt direct current power source, and the resistor R2 is also a 4.7 kilo-ohm resistor. The capacitor C1 is connected between the node N1 and ground, and has a capacitance of 0.1 microfarads. An emitter E1 of the transistor Q1 is connected to ground. The resistor R3 is connected between a pin TACH0 of the chip U1 and a collector C1 of the transistor Q1, and the resistor R3 is a 220 ohm resistor. The resistor R1 is connected between the collector C1 and the 3-volt direct current power source, and the resistor R1 is a 1 kilo-ohm resistor.
The indicating units U5-U7 all have the same structure, so only the indicating unit U5 is explained below for simplicity. The indicating unit U5 includes a transistor Q4, and a light-emitting diode LED1. A base B4 of the transistor Q4 is connected to a pin GPIO0 of the chip U1. An emitter E4 of the transistor Q4 is connected to ground.
A cathode of the LED1 is connected to a collector C4 of the transistor Q4. An anode of the LED1 is connected to a 1.5-volt direct current power source.
In use of the fan test device, the computer transmits control instructions to the chip U1 via the interface SMBUS. After receiving the control instructions, the chip U1 executes programs therein, and pins GPIO3, GPIO4, OUT of the chip U1 outputs pulse width modulation (PWM) signals to modulate rotation of the fans FAN1-FAN3. The pins TACH0-TACH2 of the chip U1 collect actual rotation speed signals of the fans FAN1-FAN3. Before the actual rotation speed signals of the fans FAN1-FAN3 are transferred to the chip U1, they are amplified by the amplifying units U2-U4. The chip U1 then determines if the actual rotation speeds of the fans FAN1-FAN3 meet a predetermined standard by executing arithmetic programs in the chip U1. Pins GPIO0-GPIO2 of the chip U1 output signals indicating test results to the indicating units U5-U7. The transistors of the indicating units U5-U7 amplify the test result signals. For the test results of the fans FAN1-FAN3 are up to standard, the corresponding light-emitting diodes LED1-LED3 of the indicating units U5-U7 will light steadily. When the test results of the fans FAN1-FAN3 are not up to standard, the corresponding light-emitting diodes LED1-LED3 will flash. In addition, by executing the programs in the chip U1, the test results of the fans FAN1-FAN3 can be transferred to the computer via the interface SMBUS, and displayed by a screen of the computer.
According to the disclosure, the interface SMBUS of the fan test device is compatible with the memory socket on the mainboard of the computer, and an additional interface for connecting the fan rotate speed test device with the computer is not needed. Thus, communication between the test device and the computer will be faster, and testing efficiency of the fan test device is improved.
It is to be understood, however, that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the embodiments, 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.
Number | Date | Country | Kind |
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201110177091.2 | Jun 2011 | CN | national |