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Description: This sealed digital temperature probe lets you precisely measure temperatures in wet environments with a simple 1-Wire interface. The DS18B20 provides 9 to 12-bit (configurable) temperature readings over a 1-Wire interface, so that only one wire (and ground) needs to be connected from a central microprocessor.

Dimensions: Probe is 7mm in diameter and roughly 26mm long. Overall length (including wire) is 6 feet.

Features:

  • 3.0-5.5V input voltage
  • Waterproof
  • -55°C to+125°C temperature range
  • ±0.5°C accuracy from -10°C to +85°C
  • 1 Wire interface

Documents:

Comments 70 comments

  • Hmmm…. I assume the black wire is GND, the red wire is VDD, and the white wire is DQ? I can’t find that data anywhere.

    • I made the assumption and it works. You would be correct.

      • thanks.

        • For anyone having trouble with the pin out, the few of these I’ve used had the colors on pins you wouldn’t expect. The pin out: Black = 5V, White = GND, Red = Signal. Not sure if this is an inconsistency with the manufacturer or if that is the pin out on all of these. I physically cut one of these open to confirm this. If you are having trouble, give this orientation a shot.

          • Doh. I tried Black = 5V, White = GND, Red = Signal and mine went up smoking.

            I had previously used “black wire is GND, the red wire is VDD, and the white wire is DQ” – which worked for me – but I ripped my connections out before realizing I hadn’t written them down. When I looked them up another time, I followed the 2nd set of advice that didn’t coincide with my device.

            Why isn’t this data part of the description? ugg….

            • I grab a newer version, and you’re correct. There may have been some inconsistencies in the wire colors inside the cable. The older version I had definitely worked with the colors I mentioned above. But, the new one fried and swelled up when I tried the pinout I previously mentioned. Trying a second unit revealed that RED=Vcc, BLACK=GND, and WHITE=SIG.

  • “-55°C to+125°C temperature range”

    i see that as rating for the DS18B20, but what about the wire jacket/insulation?

  • http://atlas-scientific.com/product_pages/sensors/env-tmp.html

    Here is one that can be used in hydroponics, food, and laboratory equipment. Sparkfun should stock this.. they already stock the pH kit from this company.

    • Atlas Scientific sold me a faulty pH stamp last year, costing me almost 2 full days of work, and then promised to send me a free EC stamp to make up for it (but did immediately replace the faulty pH stamp). They kept claiming the EC stamp was out of stock until they quit returning my emails. I just contacted another staff member though and he says he will send me the EC stamp.

  • What is the tip made out of? Some kind of epoxy?

  • I am having some issues where I read -127C from one of these, anyone have any idea why this might be happening? I am using the latest one wire and dallas lib’s…

  • Does anyone know why all of a sudden this sensor would start, seemingly at random, report -196.6F (after conversion) then bounce back to normal, about 77F. I changed nothing in the code of my Arduino or the circuit. Perhaps the device is going bad? Any thoughts?

  • I currectly own a couple of these sensors and I’m looking to acquire a couple more for high temp measuring (aprox 100 degrees celcius)… Can the material of the sensor handle this temp? I see the details specify 125 max but dont know if its been tested and stressed at these levels?

  • Can this sensor handle being frozen in a block of ice and monitor temperature during that time? Min temperature will be about -15 C, one degree accuracy is fine.

  • This ain’t food safe, right? I need it for some small wine tanks. Actually I wanted Atlas Scientific’s, but got this one.

    • I would personally not worry about using it in food, but you may feel differently. Elsewhere in these comments a customer links to a stainless-steel version which may be more appropriate for your application.

  • can this be interfaced with an arduino pro micro? if so, how.

  • It can be used to measure human body temperature?

  • I would like to know if this sensor could be connected to a phidget 8/8/8 as a simple analogic sensor? I already have the env-tmp made by Atlas scientific and it looks like the sensor must be told to send data rather than it maintains an analog voltage all the time. The procedure is turn on a digital port for millisecond, read the associated analog port, then turn off the digital port. The digital port supplies the 5 volt signal to excite the sensor. That seems I have to connect both on a digital and analog inputs and it isn’t convenient to me. I just would like an analogic sensor and nothing else.

    Otherwise, I’ll have to buy an other sensor for my project, something I could directly connect on an analogic interface. So maybe this reference : DS18B20 could be ok with the phidget. Any feedbacks are welcomed!

    • This is not an analog sensor like the TMP36. This sensor has a “1-Wire” digital interface, which requires the host system to send it a special digital command sequence to get the temperature reading, which will also be a digital sequence. Read through the links and comments to learn how best to interface to this sensor.

  • I can’t make this work with my Arduino. I have the red wire on 3v, the black on Gnd, and the white on A1. I have also have a TMP36 on A0 wired the same. With my meter, I am getting 3.3v at the solder point but nothing on the white wire. The TMP36 gives me about 0.7v. Did I do something wrong? Do I have a bad sensor?

    • Opps just learned that this is a digital sensor. Lets drop it on a free digital pin and see what happens.

      • Ok, this has been asked twice in the comments, but I can’t find the answer. Does it need the 4.7k pull-up resistor?

        • Yes it does. You can place the pullup at the Arduino or close to it, between 5V (or 3.3 if your Arduino is 3.3V) and the DQ pin of the sensor. This sensor works very well. It is stable even with a longer cable.

          My first application used the TMP36. I quickly abandoned that sensor. While it is good for monitoring a temperature inside an enclosure, it is too susceptible to noise when remote. The DS18B20 on the other hand is awesome for remote sensing and is offered in a nice probe for you. All that extra code is well worth it.

  • I have had one of these in my spa pools solar panel for about three months and it has failed. It is stuck reading 85C, power is still good at the start of the cable so assume something has broken down inside the probe. More info on error here http://www.picaxeforum.co.uk/archive/index.php/t-20929.html (post not by me). Pool has a small amount of chemicals in it, but panel can and does occasionally boil the water when the pool is at the set point. Assume this caused the problem - annoying since 125 is the range! My probe is stainless now plastic as shown in the picture.

  • can I know if this sensor can be used to measure the human body temperature plz?

  • Just hooked this thing up. Took only a couple minutes, and works great. For those who dont think its accurate enough, it comes defaulted at 12 bit resolution which equates to 0.0625°C increments. You can blow on the thing and watch the temp change. I’m going to be using it in my saltwater tank shortly, I’ll post an update when I do.

    • Accuracy and resolution aren’t the same thing. Good to know it’s fast and responsive though.

  • I want to bury it 2 meters deep into the ground to measure the temperature near my water pipes - how long can I make the cable without affecting the accuracy of measurements? I’m going to connect it to raspberry PI - will I need a power supply for the sensor or something if the wire goes around 6 meters? Silly question, I guess. Does it include the 4.7K resistor?

    • 1-wire devices are designed for long networks (hundreds of meters) so you’re most likely fine. Do read the datasheet for interfacing information; Dallas/Maxim also have application notes on best practices for reliable networks.

  • Forgot to ask this when i bought it, but is this safe to use in food production? What type of plastic coating is it PP? There is nothing about it in the data sheet.

  • Hi, just wondering if you have had any luck implementing this probe with a Libelium Waspmote? Any help would be appreciated. I took a look at the mbed example, but not sure it works with the Waspmote. Might be wrong. Thanks!

  • Was considering this for my saltwater controller, but it doesnt seem sensitive enough, nor is there any details on the casing making it impossible to consider. however, when taking apart a dead heater i found the same IC controlling it. maybe that’s why the $90 heater died only 4months after installation. anyone know of a better solution?

    • I’m curious as to how accurate you need it for aquariums. If anything you could always stick it in water that you already know is the right temp and measure what the sensor reads. I’ve used these in my fermentor refrigerator for about a year. While they may be off by up to 0.5 C, I consider it more accurate than all but one of my thermometers and they certainly don’t fluctuate IME.

    • FWIW, I’ve had a DS18B20 in my kegerator (~5C) for about 2 years.

      You can always use thermocouples…

      • mmmm kegerator… my issue is the health of the livestock, not me.. but i did come up with a way to safely use it via 1way overflow :)

  • By the looks of it, its non-shielded cabling.

  • Made my own using Sugru to seal the sensor.

  • My current thoughts are leading to those recent “Flex-Seal” commercials :D glad there’s a pre-built solution available :)

  • If you were going to decouple this, wouldn’t you want the capacitor at the DS18B20 end of the thing, instead of 6 feet away?

    • One-wire devices should not need decoupling capacitors in general, at least not according to the application notes I’ve read. In fact, if you’re using it in two-wire (parasitic power) mode, capacitors would be detrimental. Why do you ask?

      • I have been using these for a while without any decoupling and they work great, the only thing you need is a 4.7k pull up tied between the power and data line. Very accurate little sensors as well.

    • Ohh my. I was under the assumption this was decoupled. I’m sadface now. Can the bulb at the end be easily removed and then decoupled, replaced, and resealed with food safe waterproofer easily? Better yet. Just tell me IT IS decoupled.

    • Decoupling it at the sensor end would most likely ruin the waterproof seal.

  • nice!!!

    already made one with just plain heatshrink and caulking but this looks much better!

    • I do as well but I agree this is much much nicer looking than mine with liquid tape and heatshrinking

  • Nice! Was just about to checkout when I saw this. How well does this hold up to harsh environments (ie salt water)?

    • We just might have to test that out. I’m thinking about putting it in the video for next week.

    • Yeah! That would be really cool if we can use it in Salt Water Fish TANKS! (OR fresh water Tanks!) Though I would be worried using it with the Discus- they can be real temperamental with 1 Deg F change

      • You can read in the datasheet that the resolution can be better : “The resolution of the DS18B20 is configurable (9, 10, 11, or 12 bits), with 12-bit readings the factory default state. This equates to a temperature resolution of 0.5°C, 0.25°C, 0.125°C, or 0.0625°C.” The 12 bits needs 750ms to be done… but it’s ok for me.

      • I don’t believe this is accurate enough to be used as a sensor for “controlling a tank heater” as there is too many to consider and catastrophe could result. For my marine environment its simply to be used as a general reference/log/arm. The more you automate a reef, the more things that can go wrong. And when something goes wrong it costs more than I spend on gas in a year.

  • #mashtunmonitor +1

    • I’m with you, however, is it food grade or is it going to off gas chemicals into my beer?

      • My question exactly - is it foodsafe?

        We homebrewers gots to know!

      • Not likely to be food safe, especially at elevated temperatures.

        I’m surprised you guys didn’t all know about these stainless steel versions (maybe this means Sparkfun should sell them?). See stainless probes at: http://www.brewershardware.com/BCS-460-Temperature-Sensors/

        (As an aside, BrewTroller was THE reason I got into electronics and micros… but for some reason, I haven’t finished sourcing all the parts for BT, lol.)

      • Definitely interested in this. Even if it’s not food safe, would it be suitable for an application like Sous Vide where it is near food, but not directly in contact with it?

        Also, does it already have the 4.7k resistor on the data wire?

        • I just purchased one specifically for sous vide. Where the food is contained in a sealed bag and the probe is not, I don’t see it being a problem.

      • You could cover it with a long and thin cellophane bag.

      • I’m glad someone is asking this, because it was my first application thought as well.

    • +1 I’d like to use this in my hydroponics setup.

    • +1 on this. homebrew application. food safe?


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