how can i interface this sensor (lm 35) with pc by using parallal port?
please i need circuit.
thanks alot.

 

The LM35 is a solid-state temperature sensor. It's output is a voltage level, proportional to the temperature.

First, you need to amplify it and convert it to a digital format, so you computer can recognize it.

The analog-to-digital conversion is easily done by a single IC (I think it's called the DAC0808).

The amplification can be done by an op-amp and a few resistors, in a non-inverting amplifier circuit. The 351 is popular.

The C-code to use your parallel port for input is described in BUILD YOUR OWN LOW-COST DATA ACQUISTION DEVICES, by Jeffrey Hirst.

It's not that hard.

 

You will need an analog to digital convertor to convertor the analog signal from the lm35 to a digital code for the PC. You can get a parallel port Data Acquisition Module from http://www.oceancontrols.com.au/isee.htm

The other thing you can look at is a temperature sensor from Dallas Semiconductor DS1820 which has a serial digital interface that can be connected to a parallel port

 

can you give me a circuit diagram

thanks alot.