Within a computer, mechanically coupled to a generous heatsink find a blower (cooler) that has the vital function of the microprocessor kept refrigerated to obtain the best performance in processing speed. A major problem usually occurs when the fan invaded by dust, dirt and soil environment, it stops working, ie stop turning. The result This misfortune is reflected in our computer's strange behavior and even cause, in the worst cases, the silent death of the microprocessor. Do not worry, in arg will help you avoid this situation (and similar) with a very simple circuit and a step-by-step construction this alarm designed to care for your circuits.
The high performance graphics cards, microprocessors, some modern hard drives (HDD) and power supply are simple examples of systems that need to be refrigerated inside a computer . The high processing speeds, coupled with the electrical currents consumed to achieve a performance very demanding, requiring a mandatory forced ventilation. Any malfunction of these cooling elements can trigger a disaster of major proportions and very expensive . As you were mentioning in the summary of the article, not all devices that use a fan possess the quality of play when the forced air circulation stops working.
A clear example of this is the fan power of a computer. If this component fails, can completely unnoticed. A blower attached to a sink in a sound stop working can mean the destruction audio amplifier within half an hour. That is, the accumulation of temperature an electronic device that was designed for use with a heatsink and blower can not be without effective ventilation rightful . In these examples you can sum known experiments and designs signed by us using fans with sales teams that incorporate every day.
Laptops and BGA processors that abound in notebooks and netbooks are the favorite prey of the accumulation of temperature, of malfunction of the ventilation systems and of course dirt and dust environment. Over time (ie " straight after the warranty period "), welds begin to "cook and break ", causing the teams begin to fail at random and inexplicable. This is why we have begun to proliferate the bases with additional blowers to increase cooling efficiency and greater life laptop. But we always have the same problem: never or rarely do we hear that the fans stop working or diminish their performance. Only those who "have" had this kind of problems we know of the importance that a system give us an alert indicating fans stopped working. In arg, we experimented with a circuit that can find useful and here we present it.
Most fans low as those used in power bring only two cables to be fed 12Volts . Only the best quality they bring a third cable which is the reference speed of the motor , or whatever on a regular basis is known as " tachometer output." The reference given to us these engines in the third wire is a square wave whose frequency relates to the speed of the rotor . A faster, more frequently and vice versa. This information, in our circuit, will be amplified by T1, then be transformed into an information network voltage by R3 - C2, and will be compared with the tension in the noninverting input of operational amplifier.
by stopping the motor, the voltage level of decrease C2 up to tip (change state) to the operational. This behavior triggered T2 and achieved the lighting of LED . At this point we can clarify what the circuit shown, ie, we can use this output to command an optocoupler to send signals to other circuits handled by other levels of stress. We may place a simple buzzer or buzzer that by applying voltage (driving T2) starts ringing. You can also energize a relay to activate other warning systems and many other activities that let you know loads of failure and help you avoid a disaster is always wrong.
P1 adjustment is made very simple: to activate the circuit along with the fan (using the same 12Volts to energize the circuit, the circuit needs to know that the fan will arrive 12Volts and tachometer signal), the output of the operational status will be an instant high until it loads to C2 then move to a low state continuously while the fan rotates freely and our circuit receives input from the tachometer. Adjusting the control P1, find a point where the output of operational amplifier changes state. Return to the situation of having a low state output and controls, to stop the motor with your hand, the LED, after a moment, active. Releasing the engine and allow its rotation, LED, after a moment, it switches off again . This will clearly see the demonstration of operation in the last video.
And if your fan has no tachometer output?
To resolve this deficiency constructive enough to understand some aspects of the operation of a brushless motor (brushless ) as we are trying to use. In a conventional brushless motor, the rotor (moving part) is winding and the stator (housing, the fixed part) has a permanent magnet to promote responsible windings being energized through brushes . In brushless motors, however, the mobile part, where the blades that will drive the cooling air, is the one with the permanent magnet and the stator (or fixed part) has the windings through which electrical current flows. The permanent magnet rotor has 4 stator poles and four coils.
When the system is energized there will be two poles of magnet that will oppose the magnetic field generated by the stator windings. This will cause the pulse rate . The magnet poles also be responsible for activating (Or not) Switch Hall whose mission will be to disconnect the windings that do not provide power to the rotor motion. When the rotor turns, the poles in front of the Hall Switch change and, therefore, the logic state output of the device changes and alternating coils which become energized. This process is repeated as the rotor spins and the magnet poles alternate exit status of the Switch Hall. Therefore, there will be our reference connection speed: at the output of Hall Switch
The identification of this terminal is very simple. Of the three, one is connected to the supply 12Volts or in some cases, the cathode of a diode power comes from . Ie it is very easy to identify the entrance to 12Volts. Another will connect directly to GND and, finally, the third terminal is the output of Switch Hall. Really easy. Try using a cable of a different color to red and black used in the power connection to make a notable difference and avoid connection errors. Of course, if you have an oscilloscope, you can control the test result to a square wave output of the third cable that you've added, as you can see in the next video.
Finally you subtract only riding the circuit. We performed the installation on a breadboard but you can use any breadboard or printed perform dedicated to control the operation of the blower. Look at the following video LED has a small response delay, which is not instantaneous reaction. As you clarified, this is because the time constant of the network R3 - C2 . If in your case you want a faster protection action, you can "play" with these values \u200b\u200buntil times according to your need. Note that you must make a circuit for each fan to control. You may not use a single circuit for multiple blowers. Using a LM358 can control up to 2 motors and if you choose a LM324, and have the opportunity to work with four units.
As you saw, the circuit is very simple and available to construction of any experimenter. It requires no special components or expensive, just a little desire to experiment and learn. A simple connection to Switch Hall in brushless motor, which allows you to transform it into an engine tachometer output, and a simple operational amplifier, used as a voltage comparator, will help you take care of your precious electronics is always threatened by extreme temperature. From now on, the heat and the constant fear that a fan has stopped running a thing of the past. Cheer up, the construction is very easy and the benefits are great. You can adapt this idea or concept to your needs and provide active and continuous protection to any system cooled by air blowers. Tell us your experiences. Tell us how many times a fan stopped working ruined your computer. Your testimony may serve to convince many of the utility of this construction.
Source:
http://www.neoteo.com/alarma-por-rotura-de-ventilador-cooler.neo
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