Author Topic: LM35 temperature sensor + frozen goods like ice cream and chickens (Read 683 times)

dobby · « **on:** January 05, 2012, 09:46:00 AM »

Good Morning mga masters! happy new year sainyong lahat!

Ako po ay may tanong kung pwede pong gamitin ang LM35 pang measure ng temperature ng mga frozen goods like chicken and ice cream na nasa van. At ang magiging final output po ay 0 to 6V, depende po sa temperature. Gagamit pa po ba ako ng op-amp to amplify the LM35 output? Di po ba magmomoist yung sensor kapag sa ganyang environment linagay?

Maraming salamat po.

Philippine Electronics Forum · « **on:** January 05, 2012, 09:46:00 AM »

rdpzycho · « **Reply #1 on:** January 05, 2012, 10:41:32 AM »

'di ko pa 'to nagagawa, pero theoretically, yes, pwede, dahil hanggang -55 deg C ang LM35.

pwede namang hindi siya exposed doon sa mismong freezer, pwede siyang ilagay sa isang container, tapos coupled through metal 'yung LM35 doon sa freezer. kailangan nga lang i-calibrate sa temperature difference sa pagitan nung metal.

next problem would be the opamp, dapat Industrial ang temp range niya. 'yung mga commercial kasi (like LM358), 0 deg C na ang lowest. kailangan talaga ng opamp kung lalakihan 'yung range.

Philippine Electronics Forum · « **Reply #1 on:** January 05, 2012, 10:41:32 AM »

dobby · « **Reply #2 on:** January 05, 2012, 10:48:18 AM »

Thanks Sir Rdpzycho for commenting.

Anung klase po bang container ang dapat gamitin? sealed container po ba dapat? at papanu po icocouple yung metal sa lm35?Thanks.

Philippine Electronics Forum · « **Reply #2 on:** January 05, 2012, 10:48:18 AM »

rdpzycho · « **Reply #3 on:** January 05, 2012, 04:43:05 PM »

katulad nung mga thermal compound (na may glue or adhesive tape) na gamit sa computer. kailangan lang talagang sukatin 'yung difference ng temperature sa metal side at 'yung nababasa ng LM35 para merong compensation.

pwedeng sealed container, or sa inner wall nung freezer ico-couple para kasama na siya doon sa freezer.

Philippine Electronics Forum · « **Reply #3 on:** January 05, 2012, 04:43:05 PM »

PlCUSER · « **Reply #4 on:** January 05, 2012, 05:12:40 PM »

You may also consider using DS18B20 instead of LM35. Digital out na un kaya no need for op amp na, and so no need na rin for a negative supply. Meron na din available for liquid use. Encapsulated sa metal tube. Ung ginamit ko dati, walang naging loss. Same output sa walang metal cap.

Philippine Electronics Forum · « **Reply #4 on:** January 05, 2012, 05:12:40 PM »

dobby · « **Reply #5 on:** January 06, 2012, 10:29:49 AM »

Mga masters, thanks for the inputs.

Kelangan po kasi na analog type lang kasi iinterface sa analog input na pwedeng magbasa ng 0 to 6V.
yung thermistor pwede rin kaya sa mga malalamig na goods?

RaffT · « **Reply #6 on:** January 06, 2012, 12:40:32 PM »

^datasheet lang makakasagot sa tanong mo regarding thermistor

Philippine Electronics Forum · « **Reply #6 on:** January 06, 2012, 12:40:32 PM »

Philippine Electronics Forum