ADC0804 vref/2

HI i want meassure temperature,i have a LM35 temperature sensor ,out 10mv per centigrade (celcius) degree and job between -55 a 150 centigrade degree.I want meassure 0 to 72 degree mi question is how many voltage i put in vref/2 .I use adc0804 of 8 bits resolution.Thanks.Excusme for my english is poor.

You need an opamp to amplify the output from the LM35.

Nigel Goodwin said:

You need an opamp to amplify the output from the LM35.

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how many should be the gain of opamp G=2 ?

well, what do you want the vref to be? gain = vref/max_lm35_output. note that if you make the vref be 4X the max value of the lm35 reading you care about, you will be able to very simply convert the reading to actual degrees.