13.6.2015
Hello,
Agreed! The LM 35 is easier than the PT100, but I would have though that
using an OP and PT 100
would be excellent to show students the fundementals of measurement and
interface electronics .
Often the very basic circuits ie PT100 + OP Amp can have their
advantages.
I use the Raspberry Pi a lot and there are so many Sensors available,
but there is a danger of
relying on these devices and one is not perhaps as flexible.
But perhaps I am being a bit over cautious.
Nigel Trewartha
(Germany)
On 13.06.2015 07:16, Ajith Kumar wrote:
After soldering the three pins to a cable with two wires and a
metallic
shield, we put the component into the tube filled with slowly curing
epoxy resin, the excess resin flows out of the tube, and the remaining
resin becomes hard 12 hours later.
Dear Georges,
This is much easier than PT100. Output can be connected to IN1 that can measure with 12 bit resolution, 1.2 mV steps.
with regards
Ajith
According to http://www.ti.com/lit/ds/symlink/lm35.pdf,
- you can use 4 to 30 V to feed the LM35 sensor
- it drains very few current; so voltage from OD1 is OK.
- the sensitivity is 10 mV by degree. As the accuracy of expeyes DC
inputs is 5 mV when you use a conversion with 10 bits, you can know
the temperature with an accuracy of 0,5° C without amplifying.
- the linearity is very good for such a cheap component (+-0.15°C, 3 €
in small quantity at my local store)
- with no external component, you can measure temperatures in the
range
2°C to 150°C (schematics are on page 1)
Best regards, Georges.
--
Dr. Ajith Kumar B.P.
Scientist H
Inter-University Accelerator Centre
Aruna Asaf Ali Marg
New Delhi 110067
www.iuac.res.in <http://www.iuac.res.in>
Ph: (off) 91 11 26893955 (Ext.230)
(res)91 11 26897867
(mob) 91 9868150852, 91 9643258320
