Happy HolidaySs Giveaway - Last Sponsor Giveaway of the Year!

Come Enter the BrewDeals/FastFerment Giveaway!


Home Brew Forums > Home Brewing Beer > DIY Projects > Kettles, Mash Tuns, & Hot Liquor Tanks > DIY $15 Temperature Probe and Readout
Reply
 
LinkBack Thread Tools
Old 01-14-2010, 03:45 PM   #1
goatchze
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2008
Location: College Station, TX
Posts: 108
Default DIY $15 Temperature Probe and Readout

So I'm beginning to set up a RIMS system and would like to monitor temperature at several places in the process. However, thermocouples and readouts can start to get both bulky and pricey! What I want is a simple measurement device and a simple readout.

So, what to do but build my own circuit! Here's what I've come up with.



This circuit uses the LM34 IC for the temperature measurement. It prodcues 10mV/degree F. I set up a voltage divider to divide this value by 10, giving 1mV/degree F. Then I just hook up a 200mV voltmeter to readout my temperature directly!

I've ordered the parts and they just arrived. I'll be doing some testing this evening and will post up photos and results. My total cost was $50 which will allow me to set up 3 measurements and 3 read outs. That's a little over $15 each!

__________________
goatchze is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 03:59 PM   #2
uwjester
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
uwjester's Avatar
Recipes 
 
Join Date: Sep 2007
Location: Fort Collins, CO
Posts: 736
Liked 4 Times on 4 Posts
Likes Given: 1

Default

Maybe replace the 100kOhm resister next to the thermistor with a pot so you can calibrate?

__________________

--------------------------------------------------
This space intentionally left blank.
--------------------------------------------------

uwjester is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 04:05 PM   #3
lebshiff21
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2009
Location: Skippack, PA
Posts: 95
Likes Given: 1

Default

What do you put the sensor into, some sort of probe? Sorry, complete newb at this stuff, but really interested.

__________________
lebshiff21 is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 04:07 PM   #4
goatchze
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2008
Location: College Station, TX
Posts: 108
Default

Quote:
Originally Posted by uwjester View Post
Maybe replace the 100kOhm resister next to the thermistor with a pot so you can calibrate?
? The 100kOhm resistor is just there to keep the current down flowing through the indicator LED. It doesn't do much of anything else.

The LM34 is precalibrated and reads linearly. It's guaranteed accuracy is 1F at 77F and claims +/- 1.5 up to 300F. (We'll see when I get it all set up)

I'm not 100% how it works (whether there's a thermistor incide the IC, which I imagine there is), but it's output is voltage.
__________________
goatchze is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 04:10 PM   #5
goatchze
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2008
Location: College Station, TX
Posts: 108
Default

Quote:
Originally Posted by lebshiff21 View Post
What do you put the sensor into, some sort of probe? Sorry, complete newb at this stuff, but really interested.
The LM34 itself is REALLY small (5mm..the same size as a standard LED). I plan on putting it either inside of an acorn nut or inside of a copper tube with a cap. Then it's going to go into a "T" joint so that it is exposed to the wort that's flowing by. I have the TO-92 version which is all plastic and must be isolated from the liquid. If you can find the TO-46 version it is inside of a metal case whose top CAN be directly exposed to the fluid.

You can also put it in a wand if you want to.
__________________
goatchze is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 05:59 PM   #6
uwjester
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
uwjester's Avatar
Recipes 
 
Join Date: Sep 2007
Location: Fort Collins, CO
Posts: 736
Liked 4 Times on 4 Posts
Likes Given: 1

Default

Sorry, I misunderstood the circuit. I thought the led was a thermistor and the LM34 was regulating the output.

__________________

--------------------------------------------------
This space intentionally left blank.
--------------------------------------------------

uwjester is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 07:03 PM   #7
Ridemywideglide
Feedback Score: 0 reviews
Recipes 
 
Join Date: Oct 2007
Location: Montrose, CO
Posts: 270
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by goatchze View Post

I've ordered the parts and they just arrived. I'll be doing some testing this evening and will post up photos and results. My total cost was $50 which will allow me to set up 3 measurements and 3 read outs. That's a little over $15 each!
Where did you get the lm34's? I tried to get some samples from National and they wanted $54 shipping for 4 samples.. "Due to popularity" they stated.. LOL
__________________

Heirate nie eine hässliche Frau, saugt es das richtige Leben aus dir.

Primary:

Secondary:

Keg: 1554 Clone (attempt #2)

On deck: BM's Centennial Blonde

Bottled: Nada damn thing... :)

Ridemywideglide is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 07:40 PM   #8
Mista_Sparkle
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2009
Location: Aurora, Illinois
Posts: 397
Liked 1 Times on 1 Posts

Default

What exactly is an LCD Voltmeter panel? It it some fancy LCD panel that is a voltmeter or is that just attached to an LCD voltmeter and your using its output as a temperature readout as it is calibrated? and the LED is just a "hey, im on" light?

edit, I see you descreibed it as a voltmeter, so would it really be "$15 temperature probe with readout*"

*multimeter not included
long as you have a digital multimeter

__________________
Primary #1+Auxiliary: Burning River Pale Ale clone
Primary #2: empty
Primary #3: EdWorts Apfelwein #4
Conditioning/Drinking:Brewers Best Belgian Tripel, Apfelwein #3, EdWorts Apfelwein #2, Cranapple Wine, Routers Share Network Closet Strong Scotch Ale, McCormack's Old Malt Oatmeal Stout
Mista_Sparkle is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 07:53 PM   #9
goatchze
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2008
Location: College Station, TX
Posts: 108
Default

I ordered most of the parts from BGMicro (www.bgmicro.com). They have LM34DZs, which are unfortunately the least accurate LM34s, for under $2. I would prefer a LM34A but couldn't find them anywhere.


It's an LCD panel display and a voltmeter in one. It's the most expensive part of the set up at $8. It reads in mV up to 200mV. The voltmeter will read the LM34s output voltage which directly correlates to temperature. The voltage divider gets the decimal in the right place.

No multimeter is required. You could certainly use one, but they're big, bulky, expensive, and overkill in this case. I wanted a really simple piece that I could bolt on to a small control panel. Using a multimeter would make that tough.

And yes, the LED is just a "hey I'm on light" and isn't needed, but who doesn't like lights to come on when they flip switches??

__________________

Reason: more stuff
goatchze is offline
 
Reply With Quote Quick reply to this message
Old 01-14-2010, 08:51 PM   #10
Mista_Sparkle
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2009
Location: Aurora, Illinois
Posts: 397
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by goatchze View Post
It's an LCD panel display and a voltmeter in one. It's the most expensive part of the set up at $8. It reads in mV up to 200mV. The voltmeter will read the LM34s output voltage which directly correlates to temperature. The voltage divider gets the decimal in the right place.
Cool! I guess Im not surprised they make such things... This seems almost too easy
__________________
Primary #1+Auxiliary: Burning River Pale Ale clone
Primary #2: empty
Primary #3: EdWorts Apfelwein #4
Conditioning/Drinking:Brewers Best Belgian Tripel, Apfelwein #3, EdWorts Apfelwein #2, Cranapple Wine, Routers Share Network Closet Strong Scotch Ale, McCormack's Old Malt Oatmeal Stout
Mista_Sparkle is offline
 
Reply With Quote Quick reply to this message
Reply



Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Temperature Probe Malfunction BierMuncher Equipment/Sanitation 16 10-17-2009 02:07 PM
Temperature Probe Location cs2to4 Bottling/Kegging 1 08-16-2009 08:16 PM
Temperature probe correction benko General Techniques 0 08-20-2008 01:50 PM
temperature probe placement stevecaaster Bottling/Kegging 5 05-12-2008 05:36 PM
Temperature Probe Location Brett3rThanU Equipment/Sanitation 17 03-12-2008 03:11 PM



Newest Threads

LATEST SPONSOR DEALS