I am designing a Temperature Controller which will then interface to 8051 microcontroller and to the PC for supervisory controller. I need a sensor that will range from 0 to 100 degree Celcius. Can anbody help me suggest what is the sensor that I am going to use and also the A/D converter?

 

It depends. The range, (depending on cheapness vs. perfomance is enormous).

Basically, you can use a thermistor with a nice MAXIM 12-bit serial ADC.

Ken Wada

 

Try Resistor Thermal Detectors (RTDs) if you need very accurate and stable.

If not, thermocouples, or thermistors, etc. in order of cost. Places like Omega or Minco would have these. PTCs and NTCs can be used but these devices have non-linear characteristics over temp range. Or real cheap is to put a constant current say 10mA through a diode and measure the voltage drop. It would be fairly linear and should go down with temperature.

oj

 

Hi,

Your temperature range fits the AD590 from intersil. it is a linear (IC) temp sensor which is very easy to interface. You can use analog device's ADC0804 for an 8-bit conversion. For higher resolutions, a 24-bit sigma-delta IC such as HI7190 can be used with 8051. I find that if you want to interface with the PC, the easiest method would be through serial communication. if u dont want serial comm, you can make a PCI card.

regards
Kodi

 

Try http://www.sensirion.com
Good luck Henk.

 

I've recently been using DS18S20 (Dallas Semiconductor). This contains its own A/D converter and gives back the temperature in degrees C. You have to program to their one-wire interface, but once you've done that you are home free. Their sensor is a three-wire device (Vcc, Gnd, and Data). They do have an option for running on 'parasitic' power thereby possibly eliminating one wire, but I don't recommend it. They run around $5 or so retail.

 

Look at National's LM35 series. I've been using the LM35DT and is a very nice part at a very nice price.

Cheers,
- Neil

 

sure use lm45, you can see what do you need in the data sheet.

 

Dear Kodi,
I would be very appreciate if you could send me example source code of HI7190 by 8051 family.

Thanks
abbas meamarbashi

 

you r doing with microcontroller, so if you can you give me schematic of your project on my mail?

thanking you
mehul

 

ya,

You need ADC0804 (ADC), AT89C51 (as u said), LM35 (sensor), 4511 B, LM 741 (voltage follower), some capacitors and resistors I think u know abt them.

 

Does anybody have circuit diagram of PID temperature controller?