lm35 and lm335 issue

Other Hardware Sensors
1

Hi,

For my project, i want to read 2 temperatures, 1 depends on the weather (so this one can be positive or negative), which i measure with a LM335, and the other depends on a fluid (beer that has to be brewed, this one is only positive but can be higher than 100 degrees Celcius).
For this one i choosed for the LM35.
I used existing sketches for the hardware and software, but i had troubles with it.
Measuring with both sensors gave a good result from the LM335, but not from the LM35, which gave strange values.
Measuring and processing with one sensor gave good results for both!
I solved this with a resistor from 1K between the output from the LM35 and the ground.
My idea about this is that the analog input from the LM35 is internal disconnected while reading the other input, which means that the output from the LM35 floats and the value could be wrong once read en processed again.
The output from the LM335 is connected with a resistor to 5V according to the hardware example that i found on the net.
Is there anyone who had the same problem and maybe has a better solution?

IMG_1438.JPG
IMG_1438.JPG1400×1050 224 KB

2

Hi,
This post has been around for a LONG time, but it's not flagged as a duplicate - I wondered if you got it working.
I have some ideas as to why it is erratic.
If it interests anyone I can give some hints & tips on how to use both sensors at the same time.

3

You may be

Expert in many electronics areas, especially the PIC midrange series (real-time, interrupts, etc.)

but you're certainly no expert in determining which threads to reply to.

There's really no need to drag up and answer 3-year old threads on the off-chance that someone might be having the same problem now. Better just to reply to problems that exist at the moment. There's no shortage of them.