# LM34 simulation on ISIS

Discussion in 'General Electronics Chat' started by fredz0003, Sep 21, 2013.

1. ### fredz0003 Thread Starter New Member

Mar 22, 2012
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0
Hi everyone I am a newbie here, and while I do plan on getting actual components, right now I am experimenting on ISIS simulation.
I am trying to do a simple LM34 circuit, where I could show the temperatures on LED's as shown in the pic, I could easily do this with an arduino as I know programming, but I am trying to do it without microcontrollers. I am quite lost here, I know ohm's laws and I know basic electronics. What would be the easiest way to take the output voltage from the LM34 and turn on LED's base on that.

Thanks all.

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2. ### GopherT AAC Fanatic!

Nov 23, 2012
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It depends on what type of output you are looking for, there are many ways to represent values with LEDs. If you want a 10-bit binary output, you can feed the LM34 value into an analog to digital converter chip.

Many ADC chips let you input two reference voltages to allow an upper and lower limit and that chip will output a 8, 10, 12 or even 24 bit binary signal that is equally divided between the low and high reference voltage. Just connect the ADC outputs to LEDs and you can see the binary values (use high efficiency lEDs and limit current to about 1 mA (or check the ADC DATASHEET to find the output current it is capable of driving). Here you just end up with a row of LEds that you will have to convert to decimal values off-line.

You can also rin the output through an amplification circuit (op amp) to get a bigger dynamic range into the ADC for a small temperature change.

Most simply, you can buy a cheap volt meter and attach that to your circuit. A nice LED or LCD panel meter (about \$5 on eBay) will also work.

3. ### absf Senior Member

Dec 29, 2010
1,493
372
Use LM3914 between the sensor and the LED displays. The LM3914 has 10 comparators inside arranged as window-comparator and is suited fro your application.

Try get the datasheet and follow the sample schematics in the pdf.

Allen

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4. ### fredz0003 Thread Starter New Member

Mar 22, 2012
8
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Thank you guys both answers were very good, and very well explained. I think I will play with both ACD, and LM3914. Although LM3914 is more suitable for what I want to display temp from 0-100 degrees F. Thanks again

Noob Fred

5. ### GopherT AAC Fanatic!

Nov 23, 2012
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There are many solutions to the same problem. I like the LM 3914 very much. You will only get 10 different values over your voltage range. If that works for you, then this is a vey easy solution to implement - even in a breadboard.

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