ITTSB.EU Blog Forum
ITTSB Blog Specific => ITTSB - Small projects by Kiriakos & User reviews => Topic started by: Kiriakos GR on December 24, 2015, 06:41:42 PM
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About a year ago I was making plans to purchase a battery charger with advanced features and PC connectivity option.
This was using an optional LM35 probe which I did purchase it as no-name, because the branded was extremely priced.
Either way in the end I did cancel the idea of getting this charger but this special LM35 probe with a magnetic property for attaching over cylindrical battery cells this was here all ready.
After several months’ of having it unused I did thought that this it can become useful if I manage using it with my Oscilloscope.
My GDS-2102A at it slowest time/division it can do 100s and this translates to a trend chart of 16.6 minutes of recorded data.
Followed the instructions’ of national instruments at making an R-C filter so to fight back the capacitive load caused by this RG-58 cable.
In the end I did add one LM7805 for a stable 5V output.
I have to admit that I am very impressed regarding LM35 accuracy which compares with a rather expensive gadget which I own, this is used mostly in cars, and this has accurate temperature measurement so to offer ever a warning indication regarding black ice (slippery road due hard to see ice).
After confirming this LM35 sensor performance, then adjusted my Oscilloscope channel attenuation and I succeed having a measurement with two significant digits plus one insignificant.
My testing of 16.6 minutes logging this ended victorious, the oscilloscope screen cursors helped me measuring min/max in mV=Celsius and naturally time duration.
Now this LM35 sensor it does have several benefits when measuring temperature, it has potentials measuring solid objects and even moving air or liquids, but it limitation is that it takes lots of time this to recover at sudden temperature changes.
At the application of measuring temperature of cylindrical battery cells this LM35 it is definable a suitable choice, neither a battery get rapidly hot when charging, and therefore even a faster probe as for example an K-type thermocouple this would not have additional benefit to offer as dedicated temperature sensor.
My last thought now that I have good results from this circuitry, this is to find a tiny plastic box so cables & 9V battery those to be better protected. :)
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And .....
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I thought to finalize the design of my new gadget by adding one plastic box to it, this will protect all cables connections and also will work as battery cell storage box.
Luckily I was having around the plastic body of a 4.5V battery ( I think that this was a sunlight /brand).
I did added and a mini switch to it with instant glue.
And just so to never forget this sensor specifications, I did my own printed label, and even this is now protected by transparent tape (packing transparent tape roll) helping at making it waterproof and keeping it clean from stains.