Author Topic: LM35::LED temperature Thermometer ::kindly help me verify the circuit (Read 1888 times)

danechi08 · « **on:** February 22, 2009, 06:33:07 PM »

ayan.**link, idea, and photo courtesy of "electron".

since na nde ko masolve ung problem dun sa isang LED thermometer, e2 nlng ang gagawin ko.

any ideas kung may problem, or conflict sa circuit na ito?Please po kung meron, paki-advice naman.bibili napo kasi aq bukas ng umaga ng materials, at sana po tlga tama ung circuit para d magastos.aun..
thanks

I will use LM35 instead of the one in the diagram.

panu ko kaya imomount ung LM 35, e dba dpat wala siya sa mismong board?nakahiwalay ba dapat by wires?thanks.

Philippine Electronics Forum · « **on:** February 22, 2009, 06:33:07 PM »

danechi08 · « **Reply #1 on:** February 22, 2009, 06:36:54 PM »

anu po ibig sabihin nung sa LED part nung circuit?ung negative terminals ng LED ay connected?un ba un?thanks

Philippine Electronics Forum · « **Reply #1 on:** February 22, 2009, 06:36:54 PM »

♪ ♫ ♫ ♪ ♪ ♪ ♫ ♫ ♫ · « **Reply #2 on:** February 22, 2009, 07:38:11 PM »

Ito sis datasheets:

http://www.national.com/ds/LM/LM3914.pdf

http://www.national.com/ds/LM/LM35.pdf

It will help u a lot about the circuit above.

Philippine Electronics Forum · « **Reply #2 on:** February 22, 2009, 07:38:11 PM »

♪ ♫ ♫ ♪ ♪ ♪ ♫ ♫ ♫ · « **Reply #3 on:** February 22, 2009, 07:47:31 PM »

Quote from: danechi08 on February 22, 2009, 06:36:54 PM

anu po ibig sabihin nung sa LED part nung circuit?ung negative terminals ng LED ay connected?un ba un?thanks

Pagbumili ka ng assembled bargraph display dapat ganito ang specs, Common Anode X10 LEDs saka yong R8 acts as a dropping resistor for the LEDS at 10mA each so mga 100mA ang dadaloy dito @ 7.5V drop so dapat mga 2 or 5W ito.

Yong C2 ay para hindi kumukurapkurap yong LEDs mo, parang sensitivity delay siya.

Yong R1 definitely para sa threshold voltage ng bargraph or zerowing the bargraph at certain temp.

Yong R5 at R7 refer kanalang sa datasheet.

Philippine Electronics Forum · « **Reply #3 on:** February 22, 2009, 07:47:31 PM »

Shey · « **Reply #4 on:** February 22, 2009, 08:11:20 PM »

with regards to your query about LM35, it can be mounted in the board or puwede din na hiwalay as long as you are measuring the Air temperature a.k.a. ambient temperature.. if you want to measure specific areas, for example you want to measure body temperature, dapat separate sa board ang LM35..

you can directly replace LM34 with LM35 same lang ang pinning nila but iba lang ang unit ng temperature.. may few minor adjustments lang yan..

Philippine Electronics Forum · « **Reply #4 on:** February 22, 2009, 08:11:20 PM »

♪ ♫ ♫ ♪ ♪ ♪ ♫ ♫ ♫ · « **Reply #5 on:** February 22, 2009, 08:15:21 PM »

magandang gamitin yong stereo shielded wire para sa LM35 sensor para minimal ang ambient noise....or put it in a small stainless tube or copper tube filled it with silicone heat transfer grease. be careful not to expose the leads of the LM35.

danechi08 · « **Reply #6 on:** February 23, 2009, 03:22:08 PM »

regarding dun sa R1, dba potentiometer po un?san nakakabit ung left side na paa?thanks.

danechi08 · « **Reply #7 on:** February 23, 2009, 04:31:29 PM »

wah.d po gumagana ung circuit.anu kaya problem?chineck ko nmn ung connections, and tama naman po.help..

0b00000111 · « **Reply #8 on:** February 23, 2009, 04:43:28 PM »

Quote from: danechi08 on February 23, 2009, 04:31:29 PM

wah.d po gumagana ung circuit.anu kaya problem?chineck ko nmn ung connections, and tama naman po.help..

solve it by isolation...

1. remove the connection nung output ng temp sensor papunta sa lm3914.
2. check for the voltage output nung temp sensor.
3. inject a varying voltage (use potentiometer) sa input ng lm3914 and check kung nagvavary yung output..

Philippine Electronics Forum · « **Reply #8 on:** February 23, 2009, 04:43:28 PM »

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