hw to convert

[kiran2810]

i wana covert output of PT100 sensor in to voltage....

 

[cowboybob]

I googled "PT100 sensor" and there several different environmental monitoring types listed with that designation, i.e., pH , temperature, Redox, etc.

Which type are you referring to, as it makes a big difference in the method of conversion?

 

[kiran2810]

i want to control temperature, that is why need to sense the temperature 1st. and my sensor is 3 wire PT100 so i want to convert PT100 output in to voltage.
so that i can go for circuit design.
do we have any signal conditioning circuit for conversion????

 

[aljamri]

Hi,

PT100 is a Platinum sensor with a resistance that will rise precisely with the temperature rise, the PT100 Resistance Table is https://www.electro-tech-online.com/custompdfs/2012/07/pt100.pdf where the temperature against the corresponding resistance is listed.

 

[harini.c]

hi, m using nuvoton NUCLE3AN microcontroller,i wanna to set 10 micro sec timer interrupt, how to achieve this??

regards
harini

 

[kiran2810]

I have that table i want signal conditioning circuit to work accurately

 

[aljamri]

use Wheatstone bridge circuit ( Many configuration ) and directly measure the voltage, or connect it in Microcntroller through ADC and let it do your Math.

 

[DerStrom8]

hi, m using nuvoton NUCLE3AN microcontroller,i wanna to set 10 micro sec timer interrupt, how to achieve this??

regards
harini

Please start your own thread rather than hijacking someone else's. Thank you.

 

[DerStrom8]

use Wheatstone bridge circuit ( Many configuration ) and directly measure the voltage, or connect it in Microcntroller through ADC and let it do your Math.

I second the microcontroller suggestion. Running it through a uC will do everything for you. The hardest part is that you'll need to know how to program. Do you have any programming experience?

 

[WTP Pepper]

Using 5Volts (scale as required)
Tie the PT100 to ground and bias with a 100ohm resistor. This will give a centre voltage of 2.2v @ -40degC & 3.3v @+120degC or 6.8mV/Deg C
This range will give you a range of 14473 counts on a 16bit ADC. With a perfect 16bit ADC will give you a resolution to nearly 1/100th of a degree.
I can do a basic circuit soon if required, but I have given you enough info to start doing it yourself.

 

[ChrisP58]

Biasing the PRT with 100 ohms at 5V will produce about 50mW of heat in the sensor at midpoint. That will cause enough self heating in the PRT to throw your reading off a lot more than 1/100th of a degree. How much varies, depending on the sensors thermal mass and dissipation characteristics.

To reduce self heating, you should either:
1) Bias it at a much lower current, and use an op-amp to gain the voltage up.
2) Use a second uC pin to turn the bias current on just a few uSecs before reading it. Then turn the power off for a while. If the on/off time ratio is small, self heating can be minimized.

Another thing to consider when using PRTs is that, since the sensor resistance is so low, the resistance of interconnecting wire can be another source of error. If the sensor is located vary far from the power source and measurement electronics, you may need to do a 4-wire connection.

 

[WTP Pepper]

LM35 series would have been my choice of temp sensor.

 

[aljamri]

LM35 series would have been my choice of temp sensor.

You are right, although its range is wider, PT100 is usually much expensive and used in industrial and medical instruments.

 

[kiran2810]

Using 5Volts (scale as required)
Tie the PT100 to ground and bias with a 100ohm resistor. This will give a centre voltage of 2.2v @ -40degC & 3.3v @+120degC or 6.8mV/Deg C
This range will give you a range of 14473 counts on a 16bit ADC. With a perfect 16bit ADC will give you a resolution to nearly 1/100th of a degree.
I can do a basic circuit soon if required, but I have given you enough info to start doing it yourself.

can you give me the basic circuit please..... because i need the range from -40 deg c to 65 deg c.....
it will really help me....