AVR-Chat

Blue sky -

I have no knowledge of proteus, so I cannot advise in that area.

I see no functional difference between "motor" and "fan" except that  
many small fans are internally little stepper motors. Such motors do  
not function well, or possibly at all, with PWM control. Rather, your  
only choice would be a simple on/off.

In either case, for on/off control, you could use a basic transistor  
"switch". A FET is probably simpler to drive but a bipolar may be  
cheaper. However, such small fans as you describe do not take much  
current, so the transistor should not have to be very large (but  
bigger, say, than a 2N3904). I would include a reverse-connected diode  
(perhaps of the 1N4000 class) across the fan to prevent inductive  
spikes (which would damage the transistor/FET) when the switch turns  
off.

The temperature sensor would be used with a second resistor to form a  
voltage divider from Vcc to ground. Use the power supply as the ADC  
voltage reference and measure the point where the resistor and  
thermistor connect. This should be pretty straight forward. A resistor  
about the same value as the thermistor resistance at room temperature  
would be reasonable.

Again, I have no knowledge of proteus so I do not know how this fits  
into your programming considerations.

I do know that this is a relatively simple task and one that should be  
appropriate as a first project.

Jim

On Dec 16, 2008, at 8:20 PM, blue sky wrote:

>
> hi jim
> yes of course the temperature sensor output is analog so i will use  
> ADC and i will not use motor no i use fan with 5vDC yah it is small  
> the main thing i ask that what is the important part that i must  
> take care to do when i use proteus  with micro . i will write my  
> program using c language so it will be easy or using  what .i have  
> read in c language before so i think it will be not dif
>
> --- On Mon, 12/15/08, Jim Wagner <wagnerj@proaxis.com> wrote:
>
> From: Jim Wagner <wagnerj@proaxis.com>
> Subject: Re: [AVR-Chat] ATmega8l
> To: AVR-Chat@yahoogroupscom
> Date: Monday, December 15, 2008, 10:19 PM
>
> On Dec 15, 2008, at 9:54 PM, bluesky_15_8 wrote:
>
> > hi all
> > well this is my first time to programing micro controller so i will
> > use
> > proteus program to be sure first that the program will be in a right
> > way to make simulation so i want your help if u don't mind plz . i  
> use
> > proteus before but how can i use it with micro . i don't have till  
> now
> > a good idea . i want to make control on the speed of fan this fan  
> will
> > decrease the temperature in a small box but i have a question in my
> > circuit i will use temperature sensor i think that its output will  
> be
> > sure voltage so i will put voltage source to the input of the  
> micro or
> > do we have the ability to use the sensor in the proteus
> > thank u for reading my e_mail . i wait for ur replay .BYE
> >
> >
> >
> Its not clear what you are asking. If your temperature sensor has a
> voltage output, then you probably want to use the analog-digital
> converter (ADC) of the micro. Then, you wold probably want to use PWM
> to control the fan motor, depending on the kind of motor it is.
>
> Jim Wagner
> Oregon Research Electronics
>
> [Non-text portions of this message have been removed]
>
> [Non-text portions of this message have been removed]
>
>
> 



[Non-text portions of this message have been removed]