Automatic Fan

[civictypeR]

Hi everyone , I am a diploma student who has run out of ideas though of doing a final year project. I wonder has anyone thought before doing an automatic fan . This is the descriptions of my fan

1 ) a remote control fan which can be controled the speed wirelessly
2) a sensor which can sense the temperature and send signal to the remote control and show what is the temperature . Displaying the output using LCD or 7 segment .
3) A sensor ( i dont know what type of sensor suggestions) which can detect like when a person enters the room , if the fan is set to auto mode , it will automatically on .

*4 ) i wonder if is it useful like since i want to measure temperature , should i implement the feature that i can automatically on the fan if the temperature is above a certain limit to keep the room in cool condition .

Feel free to give ideas, and I have 4 months to complete the project , is it possible to be completed ? Is my scope too wide ? Do you have links about PIC ?

Thanks a lot everyone ..

 

[kjennejohn]

Hi everyone , I am a diploma student who has run out of ideas though of doing a final year project. I wonder has anyone thought before doing an automatic fan . This is the descriptions of my fan

1 ) a remote control fan which can be controled the speed wirelessly
2) a sensor which can sense the temperature and send signal to the remote control and show what is the temperature . Displaying the output using LCD or 7 segment .
3) A sensor ( i dont know what type of sensor suggestions) which can detect like when a person enters the room , if the fan is set to auto mode , it will automatically on .

*4 ) i wonder if is it useful like since i want to measure temperature , should i implement the feature that i can automatically on the fan if the temperature is above a certain limit to keep the room in cool condition .

Feel free to give ideas, and I have 4 months to complete the project , is it possible to be completed ? Is my scope too wide ? Do you have links about PIC ?

Thanks a lot everyone ..

Hi, civic. Four months should be plenty of time. Most people here will give suggestions, some will supply schematics and diagrams. I doubt anyone will just hand you the complete project to turn in.

Having said that, let's see if we can take your four points and make them one:
Let's say you want a room fan who's operation (on/off and speed) are controlled from an intelligent device elsewhere in the room. This could easilly be a PIC, AVR or some other embedded processor. The box this is in has the power supply or battery pack; the processor; a small LCD display or three 7-segment displays to show the temperature; a thermistor; and a simple low-power transmitter. All these items are readily available online. In fact you could find these items on the Parallax(.com) site.

That goes for the other unit, also, a box with the simple receiver, another processor, a power supply/battery, and a SCR or FET to switch AC to an outlet that is part of the box. An independent fan is plugged into that AC outlet. The fan can be wall mount, a table top model, or a window fan. The main reason I suggest a second box is to satisfy your request for a remote-controlled fan. You could just forget the remote-control part and put all this into one box, no radio stuff.

Separate from the first box, but wired into it, is a PIR security sensor. This a unit that uses infrared and microwave to detect the presence of a person in the room and activates an internal reed relay, which has NO/NC contacts. These relay contacts are connected to the processor inputs through two wires. This is how the controller knows when someone (or their pet, or a stray raccoon) enters the room. I suppose this is the moment the fan kicks into action and blows on the person in the room.

If you go with a window fan to keep the room cool, then you turned the fan on when the room got too warm. You knew when this was because you have the thermistor (in a voltage divider situation) to help the processor monitor room temperature. Now is when you ask yourself if you just program in a fixed temperature or provide a variable control of some kind. If you go with a window fan, the PIR is unnecessary.

Of course the room temperature is being shown on the display the entire time. If you have a means to adjust the temperature setting, the display shows this too. There are one or two (three?) LEDs to indicate status, like "power on", "set temperature" (if not done already), and more.

If the fan is plugged into a remote unit, then the second box must use the receiver to pick up signals from the control box so the fan-control processor knows what to do. It takes these commands and turns them into a signal that drives the SCR or FET in a PWM situation that varies the power to the fan. Or, of course, turns the fan off.

So, lets review:
1. you only need the PIR if you want to turn on the fan when someone is in the room.
2. you only need radio stuff if you insist on controlling the fan from a remote monitoring point.
3. you only need a variable control, like a potentiometer, if you want to set the temperature desired.
4. you always need:
- a processor
- a thermistor
- a FET or SCR to switch AC to the fan
- one, or a few, LEDs as indicators
- a display, i.e., an LCD or a few 7-segment LED displays. You'll probably need transistors for the LED displays.
- some kind of power supply to run all this, two if you have a remote box.
- a chassis-mountable AC outlet to plug the fan into.
- an AC fuse.
- a box or chassis to put all this in, two if you use a remote unit.

And more little items, I'm sure.
Someone will point out now I missed the programming language and programmer for the processor. Umm, there are processors like the Atom and PICAxe. These come with their own serial-port bootloaders and BASICs. Using these means you have to install DB9 connectors and a RS232 level-translating chip, like the MAX232, at each box. You don't need these if you program in a programmer, like the inchworm. Choose your pain...

Now, if you search this forum or online using "thermal monitoring", "PIC circuits" and the like you'll find a wealth of circuits, tutorials and diagrams to get you started. You may get quite a few of those right here. Check out Nigel's PIC tutorials here, for starters.

And have fun doing it!
kenjj

 

[civictypeR]

Thank you

hey kjennejohn ,
Thanks for the advise , but my college has a scope of asking us to use this pic model PIC 16F877. Not sure about this model , but is it powerful enough to power up the whole circuit ?

Thanks again

 

[Nigel Goodwin]

hey kjennejohn ,
Thanks for the advise , but my college has a scope of asking us to use this pic model PIC 16F877. Not sure about this model , but is it powerful enough to power up the whole circuit ?

Yes, more than powerful enough, it's not a very demanding application for a processor.

 

[audioguru]

A fan is not an air conditioner. It will cool a room only when it is cooler outside and the fan blows the cooler air into the room.
If it is hotter outside than the temperature in the room then you don't want the fan to turn on.

 

[civictypeR]

A fan is not an air conditioner. It will cool a room only when it is cooler outside and the fan blows the cooler air into the room.
If it is hotter outside than the temperature in the room then you don't want the fan to turn on.

well you have a point audioguru, well i think i have to make it a limitation as its difficult to construct an air conditioner . Well the reason i use a fan just as a device to cool or blow air . The main thing is the circuit which i want to show . It can be implemented into an air conditioning system .

Well , thanks for your advise , i get it .

 

[Klaus]

well you have a point audioguru, well i think i have to make it a limitation as its difficult to construct an air conditioner . Well the reason i use a fan just as a device to cool or blow air . The main thing is the circuit which i want to show . It can be implemented into an air conditioning system .

Well , thanks for your advise , i get it .

If you place a water evaporator in front of the fan you DO have air cooling available, provided the ambient humidity is relatively low.
So, there are other ways than compressors to condition (cool) air.
Klaus

 

[audioguru]

I know a guy who ran cold tap water through a car radiator in front of a fan.
The water was then used to flood and ruin his garden. I think some water went into his basement.
His water bill became very high priced.

My home has air conditioning but I also use fans and open the windows on cool nights to reduce the electricity bill.

 

[civictypeR]

Well audioguru and klaus . thanks for your advise. Have you all seen before the water vapor nozle which attached to the fans where you can feel drops of fine water , esspecially in those places like starbucks and humid areas, think if i can implement that circuit down , i think it can cool down the place indirectly , though i have to control the amount of water coming out from the nozle .

Well , thanks anyways for all the ideas.