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the device presented here makes the fan run at full speed for a predetermined time.speed is decreased to medium after sometime.after a period of 8 hours fan /cooler is switched off.
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it consist of IC NE555,CD4017B, 6v 100ohm SPDT relays 4nos,BC548transistor 5nos,13 diodes.
we need a detailed working ,block diagram and pcb design to make a mini project report
(23-02-2010, 12:30 PM)143com2me Wrote: the device presented here makes the fan run at full speed for a predetermined time.speed is decreased to medium after sometime.after a period of 8 hours fan /cooler is switched off.
.
it consist of IC NE555,CD4017B, 6v 100ohm SPDT relays 4nos,BC548transistor 5nos,13 diodes.
we need a detailed working ,block diagram and pcb design to make a mini project report
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During summer nights, the temperature is initially quite high. As time passes, the temperature starts dropping. Also, after a person falls asleep, the metabolic rate of oneâ„¢s body decreases. Thus, initially the fan/cooler needs to be run at full speed. As time passes, one has to get up again and again to adjust the speed of the fan or the cooler.The device presented here makes the fan run at full speed for a predetermined time. The speed is decreased to medium after some time, and to slow later on. After a period of about eight hours, the fan/cooler is switched off.Fig. 1 shows the circuit diagram of the system. IC1 (555) is used as an astable multivibrator to generate clock pulses. The pulses are fed to decade dividers/counters formed by IC2 and IC3. These ICs act as divide-by-10 and divide-by-9 counters, respectively. The values of capacitor C1 and resistors R1 and R2 are so adjusted that the final output of IC3 goes high after about eight hours.The first two outputs of IC3 (Q0 and Q1) are connected (ORed) via diodes D1 and D2 to the base of transistor T1. Initially output Q0 is high and therefore relay RL1 is energised. It remains energised when Q1 becomes high. The method of connecting the gadget to the fan/cooler is given in Figs 3 and 4.
It can be seen that initially the fan shall get AC supply directly, and so it shall run at top speed. When output Q2 becomes high and Q1 becomes low, relay RL1 is turned Ëœoffâ„¢ and relay RL2 is switched Ëœonâ„¢. The fan gets AC through a resistance and its speed drops to medium. This continues until output Q4 is high. When Q4 goes low and Q5 goes high, relay RL2 is switched Ëœoffâ„¢ and relay RL3 is activated. The fan now runs at low speed.Throughout the process, pin 11 of the IC is low, so T4 is cut off, thus keeping T5 in saturation and RL4 Ëœonâ„¢. At the end of the cycle, when pin 11 (Q9) becomes high, T4 gets saturated and T5 is cut off. RL4 is switched Ëœoffâ„¢, thus switching Ëœoffâ„¢ the fan/cooler.Using the circuit described above, the fan shall run at high speed for a comparatively lesser time when either of Q0 or Q1 output is high. At medium speed, it will run for a moderate time period when any of three outputs Q2 through Q4 is high, while at low speed, it will run for a much longer time period when any of the four outputs Q5 through Q8 is high.If one wishes, one can make the fan run at the three speeds for an equal amount of time by connecting three decimal decoded outputs of IC3 to each of the transistors T1 to T3. One can also get more than three speeds by using an additional relay, transistor, and associated components, and connecting one or more outputs of IC3 to it.In the motors used in certain coolers there are separate windings for separate speeds. Such coolers do not use a rheostat type speed regulator. The method of connection of this device to such coolers is given in Fig. 4.The resistors in Figs 2 and 3 are the tapped resistors, similar to those used in manually controlled fan-speed regulators. Alternatively, wire-wound resistors of suitable wattage and resistance can be used.
courtesy
http://electronic-circuits-diagrams
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[attachment=8739]
AUTOMATIC SPEED CONTROLLERS FOR FANS AND COOLERS
OBJECTIVE:
Aim of this project is to control the Fan/Cooler speed using LM35 temperature measurement.
From the sensor reading the controller find out in which speed it has to run the cooling fan. Then using duty cycle variation method it controls the MOSFET to drive fan in the specific speed.
The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range
This project is implemented using PIC micro-controller, driver unit for control the DC fan and LM35.
FIRMWARE DEVELOPMENT TOOLS:
1. Development tool - Mplab
2. Compiler - HI-Tech PIC C
3. Programmer - PIC Flash
APPLICATIONS:
1. Power station
2. Sugar factory
3. Power plant
4. Stabilizer
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documentation for automatic fan controller
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