[Temperature Sensor] Who's industry's default? - Page 1
Forum section: electronics / beginners

author: Mecanix
author_rank: Frequent Contributor
timestamp: April 04, 2022, 11:54:30 am
content: I understand everybody wants to be The Weatherman, and I have no problem with that! My problem is the countless sensors, ICs and other solutions that are available for measuring ambient temperature. And I don't plan on buying The Whole Internet to find a solution that actually works (done-that-been-there-before with other gizmos, no thank you very much). I need:1. 1dC accuracy max within a range of 0dC~50dCAnd that's it! Any proven 'solution & hardware' you care to share? Ideally one you've used and cross-tested against a calibrated/precision ref that is. That'd be extremely helpful. ThanksDisclosure: the temp sensor will be used inside a closed industrial enclosure (controlled environment, cooling).

author: ataradov
author_rank: Super Contributor
timestamp: April 04, 2022, 04:14:40 pm
content: DS18B20 is as default as it gets. But also being the most used IC, it is faked like crazy. So, source it only from reliable distributors. Anything you see on eBay/Aliexpress - assume to be fake.

author: crgarcia
author_rank: Regular Contributor
timestamp: April 04, 2022, 05:33:25 pm
content: Quote from: ataradov on April 04, 2022, 04:14:40 pmAre those factory calibrated? I have few and they are very inaccurate - but after reading your post, that might be because they are fake ones

author: ataradov
author_rank: Super Contributor
timestamp: April 04, 2022, 05:55:27 pm
content: Yes, the original ones are factory calibrated and are accurate to +/- 0.5 °C in -10°C to +85°C range.But unless you've got them from Mouser or Digikey - consider them fakes. DS18B20 may be the the most faked device, it has to be in the top 10 for sure.

author: magic
author_rank: Super Contributor
timestamp: April 04, 2022, 06:21:23 pm
content: Make sure you are powering them right, too.That means providing permanent Vdd power or using fairly strong pullup for parasite power. Dallas made special bus drivers which can temporarily supply high power to the bus when nothing is expected to pull it down, or IIRC I calculated that 1kΩ pullup resistor to 5V should also provide enough current and still be within the permissible sink current limits. Or maybe I'm wrong, check the datasheetThat being said, I got them to work right with 1kΩ pullup on a short cable. Fakes are omnipresent on auction sites and there are even multiple kinds of them and they vary in quality from "fairly decent at room temperature" to "absolute crap" and you never know what you will get.

author: Mecanix
author_rank: Frequent Contributor
timestamp: April 05, 2022, 09:29:59 am
content: Appreciated, guys. I'll order a batch of DS18B20 and dev around that sensor. Feels good to be able to ignore the billion others...ps. not a financial issue, it's a logistic/sourcing/testing/time wasting issue. And so I appreciate the heads up on what works

author: crgarcia
author_rank: Regular Contributor
timestamp: April 05, 2022, 10:07:30 am
content: I just bought bunch of SHT41I, that are I2C temp sensors and they look very good on the specs. Hope they work well

author: Mecanix
author_rank: Frequent Contributor
timestamp: April 05, 2022, 07:02:10 pm
content: I hope too!Side note; I remember toying with some so-called 'reputable' sop-6 ICs, some using k-type others p100, that was 3 or 4 years ago. I have no idea if the faults were caused by my circuits/parts or the ICs were completely out of specs, probably both. But anyway they were okay'ish for let's say 21dC to 25dC but below of higher they were off by 3+ dC. Some as much as 10dC within a miniscule range. Really had me losing hope in developing anything semi-precise temperature-wise so I just tossed the kits and moved on since - so that's why I'm interested to know what worked for you guys.Let us know how yours turns out!

author: MikeK
author_rank: Super Contributor
timestamp: April 05, 2022, 09:08:14 pm
content: Quote from: crgarcia on April 04, 2022, 05:33:25 pmIf you have an Arduino there is a sketch to check for suspected fake ones.

author: rstofer
author_rank: Super Contributor
timestamp: April 07, 2022, 12:02:54 am
content: I don't think you can get the DS18B20 from DigiKey, they show it as "No longer manufactured"Mouser shows a lot on order with one entry showing a delivery of mid April. This particular item comes in the giant economy package of 2,000 devices on a reel. Minimum quantity: 1 reel @ $5760I didn't explore all the entries, I just skimmed the headlines. Somebody else can do the real shopping.

author: MikeK
author_rank: Super Contributor
timestamp: April 07, 2022, 12:08:00 am
content: Quote from: rstofer on April 07, 2022, 12:02:54 amI wonder if that means that Maxim is abandoning it for a newer version. They probably lost a lot of money due to fakes.Just checked: Maxim's website says the DS18B20 is "Active in Production".

author: rstofer
author_rank: Super Contributor
timestamp: April 07, 2022, 12:10:26 am
content: Check AdaFruit, they have 70 in stock and they also have different sensor configurations. Just search for 'DS18B20'https://www.adafruit.com/product/374I'm going to go out on a limb and assume they aren't fake.

author: MikeK
author_rank: Super Contributor
timestamp: April 07, 2022, 12:11:27 am
content: Correction: Digi-Key does sell the DS18B20:https://www.digikey.com/en/products/detail/analog-devices-inc-maxim-integrated/DS18B20-T-R/3478852

author: rstofer
author_rank: Super Contributor
timestamp: April 07, 2022, 12:13:38 am
content: Quote from: MikeK on April 07, 2022, 12:11:27 amGood news! It sure didn't come up that way for me! I think my search revolved around Analog Devices and overlooked Maxim even though I didn't specify a manufacturer.Nevertheless, the AdaFruit offerings may be helpful.

author: MikeK
author_rank: Super Contributor
timestamp: April 07, 2022, 12:17:35 am
content: I'll admit that I have purchased some DS18B20's from Tayda for $1.75USD each, and the Arduino sketch told me they're probably legit. Maybe the fakes have gotten better or Tayda sells factory rejects. I should buy some legit ones to compare.

author: ejeffrey
author_rank: Super Contributor
timestamp: April 07, 2022, 04:06:36 pm
content: TMP102 is a decent option if you want I2C/SMBus instead of one-wire. Its SOT26 and requires more wires so it isn't really as suitable for remote sensing at the end of a cable as the DS18820 but it's good if you want a PCB mounted temperature sensor.

author: Terry Bites
author_rank: Super Contributor
timestamp: April 07, 2022, 04:32:30 pm
content: The NCT75 from Onsemi is a bargain 1'C I2C sensor- and they are available!