The LM34 and BS2

Ferris_Bue

Hey all,


I need some help here. I'm trying to find a schematic for the lm34 in use with the bs2. At the same time needing a way to test the lm34 to see if its works. Any help is good.

Ferris!!!!

Mike Green

Look at the application notes for the LM34 (www.national.com/an/AN/AN-460.pdf). They give a lot of information as well as a sample circuit using the ADC0831. There's lots of information on using the ADC0831 with the BS2, both in Nuts and Volts articles and in the Basic Analog and Digital tutorial.

Ferris_Bue

Thanks for that, If anyone els can help I would like it.

Ferris

dandreae

There is information in the "Process Control" text regarding the LM34 and the BASIC Stamp.· Here is a link to the text:· http://www.parallax.com/detail.asp?product_id=122-28176.· Make sure to scroll down to the "Download" section.



Dave

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Dave Andreae

Parallax Tech Support·

RDL2004

I would highly recommend Stamps in Class Process Control.

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- Rick

Ferris_Bue

Well I should say that I'm doing this on another bread bord off of the BS2. Right now all I need is just a way to test the LM34 to see if its alive. I would also like to sa is that I don't want to use the ADC0831 chip. So if there are other ways of doing this plz let me know.

Ferris!!!!

Tracy Allen

Well, you can turn the LM34 into a current source dependent on temperature and then use RCTIME to read the current. Do you have a 1 kohm resistor and a 1 uF tantalum capacitor? Connect the 1k resistor between the Vout and gnd terminals right on the LM34 package. Connect the gnd terminal on the LM34 to a Stamp input pin, p0, and also to one side of the capacitor. Connect the other side of the capacitor to Vss on the Stamp circuit. Connect the V+ terminal of the LM34 to +9 volts. (+7 to +12 Vin). Now run the following program:

result VAR Word
LOW 0
DO
  RCTIME 0,0,result
  LOW 0
  DEBUG ? result
  PAUSE 500
LOOP

If it is a standard BS2, the value printed will be something near 900 when the LM34 is at 70 Fahrenheit, and vary from around 1230 at 50 degF to 700 at 100 degF. It can be calibrated to read in temperature, but it will work better if you do get hold of a real ADC chip to add to your BS2 setup.

For protection of the Stamp, it is a good idea to put a 220 ohm resistor in between the Stamp pin and the junction of the LM34 and capacitor. It will probably need the +V terminal of the LM34 to be attached to a voltage like 7-12 volts (Vin), and won't work well on 5 volts (Vdd).

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Tracy Allen
www.emesystems.com

RDL2004

Do you have any kind of multimeter? Hook up the LM34 according to the data sheet and read Vout, it should be 10 millivolts per degree F.

edit: Also be careful, the pin out diagrams for TO-92 devices are often drawn as if you're looking at the bottom of the package and not the top like an IC. I fried my first LM34 this way.

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- Rick

Post Edited (RDL2004) : 10/3/2007 9:53:25 PM GMT

Ferris_Bue

Thanks, if anyone els can help I would like it.

Ferris!!!!

Ferris_Bue

Hey,

I have the lm34 to work. Now I need a progam for it. I could use some help.

Ferris!!!!

RDL2004

You need an analog to digital converter for the best results. The ADC0831 is easy to use.

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- Rick

Ferris_Bue

I got every thing for the curitet all ready. All I need is the progam now.

Ferris!!!!