this article specifically introduces a control device for cooling fan in the computer case.

in the process of using a computer, heat will be generated in its chassis.if the heat cannot be dissipated in time, the performance of the machine will be seriously affected. Therefore, the problem of chassis heat dissipation is always a problem that computer manufacturers must seriously consider. In order to solve this problem, the computer chassis is now equipped with if thousands of cooling fans are installed, these cooling fans will operate together with the machine starting, but the temperature in the chassis of the computer will also be different with the length of usage time.if the usage time is short, the temperature in the chassis will not be too high, and it is not necessary to to the chassis of the cooling fan all action, even don't need a cooling fan, thus, the existing computer chassis cooling fan control method is not very reasonable.

the purpose of this paper is to provide a control device which can automatically detect the temperature in the computer case and control the switch of the heat dissipation fan accordingly.

this paper is realized through the following technical scheme:it consists of a liquid crystal display, a control chip, a temperature probe and an opening key.the control chip is respectively connected with the liquid crystal display, the temperature probe extending into the computer case, the opening key and the heat dissipation fan in the computer case.

through the above-mentioned structure, whether the cooling fan in the computer chassis is switched on or off and how many fans are switched on can be controlled by the control chip and displayed on the display screen of the liquid crystal display according to the actual temperature in the chassis detected by the temperature probe, which can effectively save electrical energy, and is very convenient to use. Brief description of drawings:

fig.1 is the schematic diagram of the circuit

as shown in fig.1, this article includes:liquid crystal display 1, control chip 2, a temperature probe and an on-off key; the control chip 2 is respectively connected with the liquid crystal display 1, the temperature probe 3 extending into the computer case, the on-off keys 4 and 5 and the heat dissipation fans F1, F2 and F3 in the computer case; The model of control chip 2 is EM78P156ELP; Lcd display 1 on connected to pins 2, 6 and 7 of control chip 2 via data line, temperature probe 3 connected to pin 1 of control chip 2, switch key 4 connected to pin 12 of control chip 2, switch key 5 connected to data line of liquid crystal display and pins 3, 5 and 13 of control chip respectively, computer the three heat dissipation fans F1, F2 and F3 in the box are respectively connected with feet 9, 10 and 11.

detailed description:

during use, when the temperature probe 3 detects that the temperature in the cabinet is higher than 15 degrees celsius, the 9th pin of the control chip 2 outputs 5V high level, the first fan in the cabinet is started, and FANI/ON is displayed on the display screen of the liquid crystal display 1; Dangdang temperature probe when the head 3 detects that the temperature in the cabinet is higher than 30 degrees celsius, the 10th pin of the control chip 2 outputs a 5V high level, the second fan in the cabinet is started, and FAN2/ON is displayed on the display screen of the liquid crystal display 1; When the temperature probe 3 detects that the temperature in the cabinet is higher than 45 degrees celsius, the 9th pin of the control chip 2 outputs 5V high level, the third fan in the cabinet is started, and FAN3/ON is displayed on the display screen of the liquid crystal display 1; When the temperature probe 3 detects that the temperature in the cabinet is below 15 degrees celsius, the pin 9, pin 10 and pin 11 all output 0V low level, and all fans in the chassis are turned off. The function of the switch key 4 is:when it is pressed down, the 9th, 10th and 11th pins of the control chip 2 all output 5V high level, at the same time, the backlight panel of the LCD 1 shines, when the after switching the paste 4, the 9th, 10th and 11th pins of the control chip 2 return to normal operation, and the backlight plate is not bright; The function of key 5 is:when key 5 is pressed down, the backlight panel of LCD 1 will shine, and when key 5 is released, the backlight panel will still shine for 5 seconds 。