temperature sensor - help me with this circuit

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rainyleow

Joined: 05 Mar 2009
Posts: 5

05 Mar 2009 15:44 sensorsimages/sensorsckt9.shtml

hi...can someone who is kind-hearted help me to come out with this circuit?

A circuit that is able to show the temperature levels of human body is to be designed.
Basic circuit function:
Able to measure human body and indicates the temperature levels by using LEDs.
1. When the temperature is 37 o C, first LED will be on.
2. When the temperature is 38 o C, first LED will be off, and second LED will be
on.
3. If the temperature is 39 o C and above, the first and second LED will be off and
the third LED will be on. Besides that, a fan will be moving.

hameeds01

Joined: 23 Aug 2005
Posts: 308
Helped: 15
Location: NUST Islamabad

05 Mar 2009 16:37 temperature sensor using pic18f4520

u need a microcontroller for that

do some search on google

Kripton2035

Joined: 19 Jul 2001
Posts: 587
Helped: 20
Location: Earth

05 Mar 2009 17:37 pt100 with pic18f4520

can also be done with 4 op amps and some logic gates...

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05 Mar 2009 17:37 Ads

AdvaRes

Joined: 14 Feb 2008
Posts: 1038
Helped: 46
Location: At home

05 Mar 2009 18:16 Re: temperature sensor

hameeds01 wrote:

u need a microcontroller for that

do some search on google

Sure for simplifying the design but you can use a PT100 with simple logic function and some comparators.

invent

Joined: 06 Sep 2006
Posts: 83
Helped: 6

06 Mar 2009 5:07 temperature sensor

I remember making a temperature sensor for my final year project using PIC, but not the detail.

I found some reference material that may be helpful to you:
http://www.electronic-circuits-diagrams.com/sensorsimages/sensorsckt9.shtml

http://quozl.linux.org.au/ts/

http://www.machinegrid.com/2008/12/pic16484a-temperature-controller/

Rgds.

rainyleow

Joined: 05 Mar 2009
Posts: 5

06 Mar 2009 11:57 Re: temperature sensor

thanks for reply...u all are so kind.
i know i need a microcontroller ,however i don't know what type of microcontroller i should use. Actually i have another one hardware to do which is using PIC18F4520.Then for this hardware is it suitable to use back the same one?

AdvaRes

Joined: 14 Feb 2008
Posts: 1038
Helped: 46
Location: At home

06 Mar 2009 12:12 Re: temperature sensor

rainyleow wrote:

PIC18F4520 for such a simple application ?
Use the 16F84.

rainyleow

Joined: 05 Mar 2009
Posts: 5

06 Mar 2009 12:17 temperature sensor

haha...
But then if wanna to use PIC,don't we have to learn to program it?
If yes, why not i just use back for the same one?

AdvaRes

Joined: 14 Feb 2008
Posts: 1038
Helped: 46
Location: At home

06 Mar 2009 12:29 Re: temperature sensor

rainyleow wrote:

haha...
But then if wanna to use PIC,don't we have to learn to program it?
If yes, why not i just use back for the same one?

Frankly let me tel you that the using of µC in such application is a waste of money since we can do it by simple electronic circuit.

Let say that the purpuse of your application is to study microcontroller. You have to learn circuits design and microcontroller programming. And the better way is to start with simple microcontrollers since their architecture and the function that they have are simple to understand.

rainyleow

Joined: 05 Mar 2009
Posts: 5

06 Mar 2009 13:39 temperature sensor

the simple for u is hard for me..

AdvaRes

Joined: 14 Feb 2008
Posts: 1038
Helped: 46
Location: At home

06 Mar 2009 14:42 Re: temperature sensor

rainyleow wrote:

the simple for u is hard for me..

Hi rainyleow,

I'm sorry.
Here is the bible of bogonoff (its in french). It start from scratch. Sources are inside.

http://www.abcelectronique.com/bigonoff/loadpart1.php?par=60620

Cheers,
Advares