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This LED thermometer is designed for in home use, to read temperatures between about 60 and 78 degrees Fahrenheit. It is based around a precision temperature sensor IC, the LM34DZ. This sensor require no calibration and can measure temperatures of between -50F and +300F. While the circuit shown here does not use the full range of that sensor, it can be modified to do so by simply changing the voltage reference to U2 at the sacrifice of precision.
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|Please sir i constructed LED thermometer using LM340[instead of LM34DZ] and LM3914. I don't know where to read the temperature from in the circuit. Please how can i read the temperature of human being.Thank you Sir.|
|project is not succeeded|
|I take it this is an ac voltage not dc is that true|
|I found this circuit in my old Popular Electronics magazine from July 1996 on page 45. I decided to breadboard the circuit and test it. It worked perfectly after I calibrated it.|
|Hi, please anybody till me how i know this project working or no. when i connect the voltage all leds lighting, pleaeaeaaeeaeaeaeaeaeaeaeaeeaes tiil me.|
|I have built an extremely accurate digital thermometer, using a 4-1/2 LCD panel meter and an LM34DZ. Dont breath at it because the temp will go up 5 degrees from a couple feet! Simply purchase the PM328 meter from All Electronics and order the temperature device, download the PDF data sheets,and you will be very pleased. One word of caution. Because National Semiconductor cant seem to get their act together and test these devices, most are being distributed in the Centigrade format! Nine out of ten that I ordered from All Electronics were FORMATTED IN CELSCIUS and the tenth one was FAHRENHEIT.|
|The reason most of you folks are having trouble with these projects is because the manufacture of the LM34DZ has failed to test them! they are mostly CENTERGRADE that's right, CELSIUS! I found out the hard way by ordering a dozen or so from ALL ELECTRONICS for 2.50 each. 8 out of 12 where CENTERGRADE. Therefore I have thrown 30 dollars in the sewer because of the incompetance of NATIONAL SEMICONDUCTOR? When I asked for my money back, they, in so many words told me to piss-off.|
|it is not a trust worthy experiment i have tried this but the result is the temperature is incorrectly shown|
|I was able to get this to operate by removing the capacitor C2. You should only be using this capacitor if your LED leads are more than six inches in length.|
|I designed the circuit bt the problem is that all the LED glow immediately when u supply the voltage..So it doesn't;t show normal temperature like a barometer... Waste of time in designing this circuit...|
|Thats a good project but I'm not able to know that how we can desplay o/p temperature and second question is "Can we use LM35DZ instead of LM34DZ|
|Anyone make works this circuits?|
|did anyone get work for this project???anyone see this comment,please answer it, coz i really need to make this project works but i can't|
|simple and nice idea|
|Extremely good. But tell that how o/p is displayed?? How we will come to know the temperature?? I want to design it as college miniproject.|
|really very good. excellent ideas. keep it up|
|how i can make led thermometer? plz give me it's process|
|how did I know if the LED thermometer we did is correct.how did we check for it??????????????? thank you|
|what is the device that displays the temprature? is it the leds or what???|
|this page is veryused in my project work thankyou|
|it is very useful to me|
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