digital thermometer without microcontroller

Thread Starter

pinktoadette

Joined Apr 29, 2015
2
is it possible to do this without a microcontroller?

I would like to use lm34 with 4 digit 7 segment display.
looked around and i know i need an analog digital converter. But if that's all i need, why do i need a full microcontroller like some of the projects out there?
 

wayneh

Joined Sep 9, 2010
17,498
Just get a voltmeter with those specs.

Example (not an endorsement!)

If you need to scale it differently, you could add an op-amp circuit in between, to convert the LM34 output into a different voltage range.
 
Last edited:

AnalogKid

Joined Aug 1, 2013
11,034
is it possible to do this without a microcontroller?

I would like to use lm34 with 4 digit 7 segment display.
looked around and i know i need an analog digital converter. But if that's all i need, why do i need a full microcontroller like some of the projects out there?
Among other tings, the microcontroller converts the straight binary out of the A/D to binary-coded decimal (BCD) for the displays. The output of a typical A/D converter is a single word of 8 to 16 bits that represents the analog value in straight binary. A multi-digit display needs 3 or 4 bits for each digit to display the values 0-9. For example, a 12 bit A/D can output binary values that represent to 4095 in decimal. To drive 4 decimal digits takes 15 bits in BCD.

As noted above, there are BCD-coded A/D converters specialized for the digital panel meter market. With an opamp or two for buffering and scaling, they will do exactly what you want.

ak
 

absf

Joined Dec 29, 2010
1,968
is it possible to do this without a microcontroller?

I would like to use lm34 with 4 digit 7 segment display.
looked around and i know i need an analog digital converter. But if that's all i need, why do i need a full microcontroller like some of the projects out there?
Should be possible. LM35 output 10mV per degree C, i.e. 1000mV = 100°C. But then just the ADC chip alone would cost many times more than a cheap PIC uC. Not to mention the convert-display logics to convert Binary to BCD and decode them to 7 segments displays.

A cheap 16F 18-pin PIC would cover all of that provided you already know how to use it.

Allen
 

Søren

Joined Sep 2, 2006
472
is it possible to do this without a microcontroller?

I would like to use lm34 with 4 digit 7 segment display.
looked around and i know i need an analog digital converter. But if that's all i need, why do i need a full microcontroller like some of the projects out there?
The CA3161/CA3162 is good for 3 digits, which should do for most things.
But they may be as scarce as the ICL voltmeter IC's and hence carry a ridiculous price tag
 

GopherT

Joined Nov 23, 2012
8,009
is it possible to do this without a microcontroller?

I would like to use lm34 with 4 digit 7 segment display.
looked around and i know i need an analog digital converter. But if that's all i need, why do i need a full microcontroller like some of the projects out there?
You can get a simple panel meter. Some panel meters can be configured to place the decimal where needed for a given input range. All for 5 to $20 - depending on quality and store.
 
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