hybridfree/eevblog-posts huggingface dataset:
Thermal insulator for thermoelectric - Page 1
Forum section: electronics / projects

author: elimenohpee
author_rank: Contributor
timestamp: November 20, 2016, 06:24:00 pm
content: I have a couple of projects in mind that make use of a thermoelectric generator for the power source, unfortunately a quick scan of newark and mouser shows that the max differential temperature a lot of the peltier plates can handle is generally less than 100C (unless I want to shell out a lot of money which would defeat the purpose of the project). The application I'm thinking of using them in could reach temperatures up to 400C potentially. I was wondering if there is a way I could insulate the hot side of the peltier to reduce the temperature it sees. Does anyone have any suggestions to point me in a particular direction? Usually the goal is to couple as much heat the heat sink as possible, but I want to do the reverse. Thanks!!

author: SeanB
author_rank: Super Contributor
timestamp: November 20, 2016, 06:30:07 pm
content: How about instead having a longer path to the element, using a thin aluminium Z plate so the heat has to flow along the long side, then spread out over the end. Insulate with glass wool ( about the only cheap thing that will survive 400C) and put a decent heatsink on the cold side, so the element is closer to ambient temperature. You want a steep gradient, so the long thermal path is a lot better and having a low thermal resistance at the cold side is a lot better.BTW most peltier elements are specced for 70C maximum, they might start melting at 100C, as they are based on Gallium bismuth alloys, which are very low melting point alloys.

author: JimRemington
author_rank: Regular Contributor
timestamp: November 20, 2016, 06:44:16 pm
content: If the temperature anywhere on the Peltier device exceeds about 90 C, you will unfortunately need to shell out for the ones using more expensive alloys. Marlow Industries has reasonable prices for TEG modules rated at 230 C, and sell some in small quantities to private individuals.http://www.marlow.com/power-generators/standard-generators.html

author: elimenohpee
author_rank: Contributor
timestamp: November 21, 2016, 01:43:31 pm
content: I'm going to do some more testing to see what the actual temperatures the device would see, but if it gets as high as I think, I'll probably just scrap it. Thanks for the info though!

author: mikerj
author_rank: Super Contributor
timestamp: November 21, 2016, 02:05:54 pm
content: At that temperature you should probably be looking at conventional thermopiles that use thermocouple junctions rather than Peltier based devices.
Thermal interface isolator that use phase change material - Page 1
Forum section: electronics / projects

author: Vicus
author_rank: Regular Contributor
timestamp: November 02, 2022, 05:38:24 pm
content: I repair stuff (mainly in the audio-video-light industries) and sometimes original manufactures uses thermal conductive and electrical isolator that uses phase change matherial as thermal conductor. I have no idea how they work but I think that they work better than silpad not just because they offer better conductivity but most because they have a very low thickness. Is it true? Can this material be reused? And if I don't replace components? Does the compound reflow when is heated up?I think that every time I see this material it is green and I think is the bergquist thf 500 or the 1600. I can easly buy fischer electronik isolator, the silpad type or the phase change type. Can they be considered equivalent or the berquist is needed?Any experiences are much apreciated.
Thermal management of SOHO network stuff - Page 1
Forum section: electronics / projects

author: madires
author_rank: Super Contributor
timestamp: May 13, 2014, 02:09:57 pm
content: While dusting my home office I spotted that the shelf area where my DSL modem stands is quite warm. It's common that DSL modems become hot, but it bothers me and I've done a little experiment. I taped a temperature sensor to the modem's bottom and measured the temperature when it was standing with it's feet directly on the shelf and when it was raised by 2cm with two U profiles to get more airflow (of course with some settling time). I also checked some other devices:DevicestandardraisedDSL Modem56°C47°CRouter40°C36°CVoIP-ATA35°C32°CThe results aren't anything unexpected but the numbers are interesting. Mounting the hotties vertically, if feasable (some got a nice vertical stand in the box), or raising them a few cm really helps. The electrolytic caps of the DSL modem would last twice the time ;-)

author: SeanB
author_rank: Super Contributor
timestamp: May 13, 2014, 04:07:21 pm
content: It does help. Most of the time the plastic case has a few token air flow holes, and mounting vertically means that they actually can do air flow by convection. As well I opened my one and saw the main chip runs warm, so used epoxy to glue a small aluminium heatsink ( ex old south bridge) on top of it to keep it cooler. Dropping temperature by 10-20c helps a lot with reliability.
Thermal pads on LEDs - can I connect them together ? - Page 1
Forum section: electronics / projects

author: chris_leyson
author_rank: Super Contributor
timestamp: May 01, 2018, 01:48:03 am
content: I'm doing a layout for some OSRAM SSL 80 LEDs on IMS board and just wondered if I can connect the isolated thermal pads together because that way I can get more copper on the board. I'm putting three LEDs on the boards connecting them in series. The data sheets don't say anything so I assume it's probably OK.

author: alexig
author_rank: Contributor
timestamp: May 03, 2018, 01:21:09 pm
content: I would say don't connect them together, the data sheet marks them as a "No contact pad".https://au.mouser.com/search/Refine.aspx?Keyword=157971343&FS=True&Ntk=P_MarCom&Tb=datasheets

author: nrxnrx
author_rank: Unknown
timestamp: May 03, 2018, 02:55:44 pm
content: I foundhttps://www.soselectronic.com/a_info/resource/d/osram/Details_to_the_Assembly_and_Solder_Pad_Design_of_the_OSLON_OSLON_SSL_and_OSLON_Square_Family.pdf.At page 3 there's this:QuoteI couldn't find out why.
Thermal printer - Page 1
Forum section: electronics / projects

author: facumedica
author_rank: Contributor
timestamp: November 10, 2014, 01:02:34 pm
content: Hey guys! I was looking for some kind of printer and I found a Thermal printer in a POS device (that thing that shops use to charge you when you buy with your credit card).Last time I saw it working was 4 years ago or so, but now it didn't power on, but I think it is because of a internal dead battery (which I measured exactly 0V, and it was a Lithium one). I didn't wanted to turn it on anyways... (Don't turn it on, take it apart!)Back to the issue... Because it doesn't power on I can't measure it while printing. So I took it apart, and took some photos of it, maybe you can help me a bit.What I know so far:-It has a stepper motor, a four wires one, to move the paper-It has a IR emitter and a receiver, to check if there is paper.-One of the wires coming from the flat wire goes to one of the springs, so I automatically asumed that it is ground.-Possibly 3.3v logic, since the LCD and some other parts works at that voltage. Not sure, just a though.Anyone knows how to get it working? How can I test it without the original circuit working? Anyone used one of this before?I leave you some pics, and no, there isn't a code to look it up on google.
thermal problem with asymetrical half-bridge - Page 1
Forum section: electronics / projects

author: vodka
author_rank: Frequent Contributor
timestamp: June 08, 2014, 06:12:44 pm
content: hello,i have a mosfet(irfz46n) that it warms up when i switch on the power supply with a load inductor.The power supply consume 0.22 A with the current limited(tested with multimeter and display power supply),this mosfet warms up a few seconds while the schottky diodes and the other mosfet is as freeze as a fish.So the hot mosfet and cold mosfet switch on at same time and have heatsink .Below is my schematic and the problematic mosfet is the left

author: Andy Watson
author_rank: Super Contributor
timestamp: June 08, 2014, 06:37:34 pm
content: I would include a damping resistor in the gate of each Mosfet to ensure stability. Q1 is unlikely to turn-on fully thereby dissipating more power than necessary. Q4 is upside-down.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 09, 2014, 12:11:50 am
content: Many basic things wrong with this circuit...1. Oscillator and comparator are using really slow op-amps as comparators2. Supply is 12V so the 12V zener is redundant3. Op-amp supply is +/-15V yet gate signal is apparently intended to be +12/0V, causing U2 to drive short-circuit current (bad) into Q3/Q4 base (worse) all the time4. Q1 gate drive is insufficient to saturate, gate voltage must be above +12V when 'on'5. None of this matters anyway, because the load shown is a 0.47uF capacitor, which will charge once, and then do absolutely nothing. Unless you meant that to be something else...Tim

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 09, 2014, 01:06:08 am
content: Hi,The problem is with the Gate drive for Q1. The gate can only go to +12V minus Q3 vbe. The source of Q1 can only go to:+12V minus Q3 vbe minus Q1 VgsSo the power lost in Q1 is equal to I drain x (Vgs + Vbe)look at this post:https://www.eevblog.com/forum/projects/inductor-saturation-tester-alternative-route-to-dump-the-excess-energy/msg181720/#msg181720I use a P Channel and an N Channel in asymmetrical bridge.Regards,Jay_Diddy_B

author: vodka
author_rank: Frequent Contributor
timestamp: June 10, 2014, 05:05:24 am
content: T3sl4co1lwhy is not saturate the gate ? when the datasheet says that the voltage gate is among -20 and + 20 VJay_Diddy_Bwhy is the reason for using the channel p and not channel n?

author: Dago
author_rank: Frequent Contributor
timestamp: June 10, 2014, 06:08:59 am
content: Quote from: vodka on June 10, 2014, 05:05:24 amBecause then he'd need a floating or isolated gate drive. Remember gate voltage is referenced to source and for the upper FETs the source is not connected to ground.
thermal resistance calculation - Page 1
Forum section: electronics / projects

author: aniket
author_rank: Contributor
timestamp: March 22, 2019, 07:58:33 pm
content: hi ,how do i calculate the thermal resistance for a black anodized aluminum sheet with dimension of 100 x 50 x 5mm.Considering 167W/m3 of thermal resistance for alu , I reach at 0.0041750 for the sheet intended for my application , but that's the thermal resistance for heat transfer within the aluminum , I need to calculate for aluminum sheet to ambient air at 40C .I need to dissipate a total of 6W , any help will be highly appreciated .......

author: jonroger
author_rank: Regular Contributor
timestamp: March 23, 2019, 03:34:03 am
content: https://www.heatsinkcalculator.com/free-resources/flat-plate-heat-sink-calculator.html

author: soldar
author_rank: Super Contributor
timestamp: March 25, 2019, 11:24:12 am
content: Quote from: aniket on March 22, 2019, 07:58:33 pmNote that all models are quite simplified.Aluminum to air will be very variable on whether it is still or moving air, whether the aluminum sheet is vertical or horizontal, one or two sides exposed, etc.On the other hand, this is very easy to measure. You can just build it and measure it.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 25, 2019, 03:40:48 pm
content: Quote from: soldar on March 25, 2019, 11:24:12 amJust want to double down on Soldar's comment. Unless you are willing and able to do a detailed finite element analysis of your device and its surroundings you will just be getting a ballpark answer, and even the detail analysis will be dependent on knowing things like the surface roughness of your heat sink and details of the anodize process. Things which are somewhere between difficult and impossible to get.So make a test model and measure it. Be sure your design has margin to deal with manufacturing variation. Since it is the junction temperature of your silicon that matters make sure you have a way of knowing that in your measurements. (The diode equation is your friend here).

author: jonroger
author_rank: Regular Contributor
timestamp: March 27, 2019, 04:45:05 pm
content: I get around 90C junction temperature with airflow on both sides. But +1 on "details matter".
thermal resistance help - Page 1
Forum section: electronics / projects

author: Opticalworm
author_rank: Contributor
timestamp: January 28, 2011, 12:46:22 pm
content: Hi everyone,I don't think I fully understand the information some manufactures provide on thermal resistance. Normally, I would take that resistance (lead to ambient) multiply it with the expected power and then add the maximum ambient temperature. Now if that temperature falls inside the normal working range then I'm happy to use as is.However, take this Zener diode (1SMB5925BT3GDatasheet), the datasheet says that this device is a "3watt plastic surface mount Zener diode" which I can only assume it means that this diode can run find at 3Watts without heat sink. Now if you look at the table on the first page "maximum rating" it gives a thermal resistance from junction to lead of 25 °C/W with a maximum power dissipation of 3Watt where on the next row it says junction to ambient is 226 °C/W with maximum of 550mWatt.Which thermal resistance should I be using if I want to pass 2.5W through it?

author: Psi
author_rank: Super Contributor
timestamp: January 28, 2011, 01:38:27 pm
content: The 3W device power rating is the max power the junction can handle without damage, all it really tells you is that it can handle 3W for an unknown length of time. It is likely that if you follow the datasheet for pcb pad size the component will handle near it's rated power without overheating but to find out for sure you'd need to calculate just how hot it will get at that power.Most devices give both junction-to-lead and junction-to-ambient so you can work out the temperature rise for which ever option you use (heatsinked and/or in open air)You will need to lookup the heat dissipation of the standard copper pcb footprint for that size component or the heat dissipation for a given area of pcb copper to work out the exact temperature rise at 2.5WHave you watched Dave's video on this subject? it might answer some questions.http://www.eevblog.com/2010/08/15/eevblog-105-electronics-thermal-heatsink-design-tutorial/

author: Opticalworm
author_rank: Contributor
timestamp: January 29, 2011, 09:29:47 am
content: I see now why for junction to lead Thermal resistance is a smaller than Junction-ambient and why they have different power dissipation. If I want to achieve the full 3watt dissipation then I will need to look into a better way to cool this zener (For example like Psi suggested PCB footprint).Psi Thank you.
Thermal resistance of an SMA connector - Page 1
Forum section: electronics / projects

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: August 27, 2018, 01:21:19 pm
content: This is perhaps an odd question, but I was wondering if anyone has a ballpark idea of the thermal resistance of an SMA connector joint?I am thinking about making a lighting setup using RG402 semi-rigid coax to hold tiny LED modules on the end. In fact, there are modules that are just the right size and would fit between the pins of the SMA connectors I have laying around. Since it will be pretty much right up agains tthe SMA connector, I was thinking that I could use the SMA connector and cable to do part of the needed heat-sinking.
Thermal Test Board Project Suggestions - Page 1
Forum section: electronics / projects

author: ransonjd
author_rank: Contributor
timestamp: February 22, 2018, 06:05:54 pm
content: I'm thinking of doing a project to test how various PCB factors affect surface mount component thermal resistance to ambient. I'm especially interested in how much nearby disconnected copper pours affect thermal performance.My plan is to design an array of PCBs with different copper arrangements, but identical component arrangements. I'll use a surface mount diode with a thermal pad as the heat source. The diode will have kelvin connections to measure the voltage across it, and a current sensor inline with its power leads. On the PCB, I'll put down temperature sensors at various locations. I'll probably also glue a thermocouple to the top of the diode. The whole thing will be in a large box to prevent drafts, and I'll measure box's ambient temperature with another thermocouple.My general goal is to keep the cost down without compromising the results.I'm interested in suggestions in a few areas:1. What't the best cheap way to monitor PCB temperature at various locations on the PCB? Diodes are cheap, but would require individual calibration. RTDs are expensive. Preferably I would just use a cheap, off-the-shelf temperature logger, or an IC that can be interfaced to a PC with minimal overhead.2. What variables should I test? I'm considering copper area, connected vs disconnected copper, via size, via number and 1 vs 2 vs 4 plane layers.3. Anything I should change in my experimental setup?

author: ogden
author_rank: Super Contributor
timestamp: February 22, 2018, 06:55:35 pm
content: Consider NTC for temperature sensing. Any low cost temperature sensor will need calibration, so you shall plan two or three point calibration using external temp reference, for every PCB.Thermal imager would solve temperature sensing.

author: ransonjd
author_rank: Contributor
timestamp: February 22, 2018, 07:19:36 pm
content: Right, NTCs, the obvious solution. There apparently was a hole in my head today.Thermal imager would be nice. Dealing with emissivity errors might make it more work in the end.

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: February 23, 2018, 12:47:24 pm
content: Quote from: ransonjd on February 22, 2018, 06:05:54 pmDefinitely, some fine wire thermocouple(s). One of the wire of T types thermocouples is copper and is easily solderable with standard methods (Soldering iron + soldering wire).As a guideline for your experiments : A standard 35µm copper layer is about 10 times more conductive than a standard 1.6mm FR4 epoxy layer.
Thermal vias calculator software or in Altium - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: March 14, 2022, 05:40:52 am
content: Hi,I thought Altium had thermal via calculating feature but cannot find it. Does it have it?Regardless, are there any free thermal via calculators?Thank you

author: Dave
author_rank: Super Contributor
timestamp: March 15, 2022, 06:57:37 pm
content: Not aware of Altium having this feature. I useSaturn PCB Toolkitfor this purpose.

author: strawberry
author_rank: Super Contributor
timestamp: March 15, 2022, 07:29:30 pm
content: https://www.altium.com/pdn-analyzerI guess it is not cheap

author: ricko_uk
author_rank: Super Contributor
timestamp: March 17, 2022, 06:13:29 pm
content: Thank you Dave and Strawberry
Thermally conductive foil - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: November 04, 2022, 07:14:41 pm
content: Hi,where to buy a thermally conductive foil between an aluminium heatsink and an array of transistor (working voltage up to 600 V). It would be nice if it has adhesive on one side. I need approx 35 (1.5 inch) x 200 mm (8 inch) size, up to 100 um (4 mil) thicknes and with reasonable price - what I found on e.g. mouser costs almost more than what the price of the the device, I'm trying to repair, isI like e.g. Kapton MT+ material but no idea where to buy it. I need just one piece for my repair project.

author: moffy
author_rank: Super Contributor
timestamp: November 05, 2022, 12:15:21 am
content: Foil as far as I am aware implies metal, i.e. copper or aluminium foil, which is of course electrically conductive. You need an insulating but thermally conductive "film" like that you mentioned "DuPont™ Kapton® MT+ polyimide film". Without knowing the details, like the thermal resistance you need, only generalities can be suggested like Mica, which has good thermal and breakdown characteristics but poor mechanical attributes, it's brittle.

author: jmelson
author_rank: Super Contributor
timestamp: November 05, 2022, 05:02:45 pm
content: Bergquist is the major brand for this, they have a wide range of things. GapPad is a compressible gap filler material. They also have thin fils with adhesive at least on one side. I use a bunch of individual heatpad pieces pre-cut for TO220 transistors.Jon

author: ejeffrey
author_rank: Super Contributor
timestamp: November 05, 2022, 09:07:11 pm
content: Kapton film is usually the DIY thermal film of choice. You can just buy a sheet of it and cut to the size you need. It's expensive as things go, but for the sizes you need for transistor mounting it's usually negligible.However, at 600V I would probably look at mica insulators. Kapton has good dielectric strength but I would want a part designed for the voltage I am using rather than buying random film and cutting it up. A bur on the transistor that pokes into the Kapton won't be a big deal at 40 V like in an audio power amplifier or lab power supply, but it could create a weak spot that eventually fails. You can easily get mica washers designed for up to 1 kV. You will need thermal grease as the mica doesn't fill gaps.https://www.newark.com/c/cooling-thermal-management/thermal-interface-materials/thermal-insulators?insulator-body-material=mica
Thermister - Page 1
Forum section: electronics / projects

author: jismal
author_rank: Contributor
timestamp: March 12, 2018, 05:29:13 am
content: Hello allCould anyone find out a Thermistor ic which could operate at low voltage as 2.5v and high as 5v.I could only find some couple of them. The project is to make a device which is battery powered (3V-2.7V)which can sense temperature using thermostat. I cannot use a boost converter for this as it made to be a low cost solution. The collected data is pushed via BLE 4.0 to an android app.1) MAX6682.(3v to 5v)2) LTC2983(2.85 to 5.25v)

author: jbb
author_rank: Super Contributor
timestamp: March 12, 2018, 05:37:39 am
content: Quote from: jismal on March 12, 2018, 05:29:13 amErr, I think 'thermostat' isn't the word you're looking for. Those tend to be on/off devices.If you want to use a thermistor, you can do that in a few ways. A cheap but effective method is to make a resistive divider and use a micro controller ADC, then correct for non-linearity with some calibration curve. The power to the divider can be switched on and off with an IO pin and a P channel MOSFET to reduce sleeping current consumption.It depends a lot on your accuracy, noise, and protection requirements. Do you want the thermistor on the PCB, or mounted off the PCB on some wires? What temperature range and accuracy do you want?

author: jismal
author_rank: Contributor
timestamp: March 12, 2018, 06:52:49 am
content: No i am looking for thermistor based solution so i could place the sensor in the skin and acquire the data. I am looking for a single chip solution because i maxed out the adc channel in the controller i am using. I also cannot use any other solution which requires a calibration of some sort. Desperately looking for a single chip solution. Anyway accuracy will be of +-2 degree Celsius.Thank u you for your fast reply jbb.

author: jbb
author_rank: Super Contributor
timestamp: March 12, 2018, 09:38:57 am
content: OK, you’ll have to do some error calculations, I don’t know if you can do 2 deg C accuracy without calibration.Have you considered a dual analog MUX chip? Use 1x GPIO for control. Use 1 MUX to switch between normal analog input and thermistor network. Use second MUX to energise thermistor network.To minimise drift, the measurement should be ratiometric. That is, the power supply to the thermistor chain should be the same as the reference voltage. This removed changes in reference voltage from your error sources.

author: MasterT
author_rank: Frequent Contributor
timestamp: March 12, 2018, 01:25:51 pm
content: DS18B20 - minimum = 3 V.DHT12 - 2.7 V.

author: rheb1026
author_rank: Regular Contributor
timestamp: March 12, 2018, 05:45:36 pm
content: I have used the LTC2983 at work, and it works very well. Accurate to +/- 0.1*C with a $10 thermistor. It has something like 20 channels available for different temperature measuring devices (diodes, thermocouples, RTDs), but I think LT has made one a little cheaper with 10 channels (LTC2985 maybe?). Only downside is that it maxes out at 6 samples per second per channel. Also not particularly cheap in single quantities ($30)
Thermistor HELP - Page 1
Forum section: electronics / projects

author: lucasromeiro
author_rank: Newbie
timestamp: December 17, 2022, 02:31:31 pm
content: Hello guys.I'm using an efr32bg22 Bluetooth module and would like to read a thermistor with it!I've never used a thermistor.Reading a little about the subject, it seems a little complicated to me.There are some formulas for obtaining a conversion but apparently the best way is to use a conversion table.Unfortunately I don't know how to do any of them.I would like to use the table or a method that helps to have greater precision.I bought 2 thermistor models and I have them here with me:NTCSP103JF103FT1STX06F103F3435ERI had a temperature sensor that used a thermistor to measure the temperature inside a refrigerator. I want to do the same thing.I disassembled the sensor and the circuit I found was as follows:I imagine that I can replicate this circuit, but the part of converting the ADC signal to the temperature accurately I still don't know how to do it.Can someone help me?Important: I intend to use the range from 30 to -40 degrees celcius.Most of the time it will operate in the range of 10 to -20 degrees celcius (inside a fridge or freezer).Can anyone help me with this?
Thermistor string required - Page 1
Forum section: electronics / projects

author: deepak.midri
author_rank: Newbie
timestamp: June 02, 2014, 01:30:09 pm
content: I looked for several thermistor strings but none exactly matching specs I need.Do anyone has used these strings before:1. Temperature range: -30C to +60C2. Accuracy: +-0.05C3. Input voltage: 0-12V4. Cable: Cold weather Teflon or equivalent cable5. No of sensor: 126. Output: Digital RS232/RS485 or analogHere is cross-post on:http://forum.allaboutcircuits.com/showthread.php?t=98240
Thermochron Ibutton - Page 1
Forum section: electronics / projects

author: fifty60
author_rank: Newbie
timestamp: April 22, 2014, 01:13:01 am
content: I finally purchased the Ibutton's that Dave recommended on the EEVBlog. Problem is that I cannot find the software to make them work. Right now the ibuttons are not in a case, and look like old calculator or watch batteries. Are they recording temperature right now? Do I have to program them to begin recording temperature?Can anyone recommend any software to use with the ibuttons? I just want to do some temperature data logging, a few hours at a time."Bob's my uncle...no worries."~ Dave

author: SL4P
author_rank: Super Contributor
timestamp: April 22, 2014, 01:43:32 am
content: A couple of things.First - do you have a touch point - or making your own?I'm using a USB unit from Dallas-Maxim - just to make it easier.(But not the Thermocron - I'm using other iButtons)Second - I'm sure here's a developers app out there somewhere for the Thermocron, but if not - there's a lot of info on the net for 1-wire communications, and with a bit of patience - you can write your own.Off the shelf -http://www.maximintegrated.com/products/ibutton/solutions/search.cfm?Action=DD&id=253
Thermocouple housing materials? - Page 1
Forum section: electronics / projects

author: deltawars
author_rank: Contributor
timestamp: November 07, 2014, 08:52:00 pm
content: I'm building a cryogenic cooler and I need to accurately measure temperatures around ?196 °C but there are many different thermocouple housing materials like ceramic, stainless steel and glass but what is the difference between them?

author: qwaarjet
author_rank: Regular Contributor
timestamp: November 08, 2014, 12:54:52 am
content: The housings are mainly for environmental protection and ease of mounting. glass is chemically inert, ceramics are good for high temperatures, stainless is good all around. Generally unless you have a chemical reason not to use stainless is the way to go. I mainly use stainless or weld the thermocouple to the object of interest. Though most the the cryogenic systems I have used use silicon diodes instead of thermocouples for temperature measurement.

author: LukeW
author_rank: Frequent Contributor
timestamp: November 08, 2014, 08:18:10 am
content: Thermocouples are not the most common or most accurate choice of sensor in cryogenic applications. They are mainly just used in very high temperature systems.Lakeshore (who are well known for professional temperature sensors in scientific and technical cryo applications) has some good info on their website.http://www.lakeshore.com/Products/Cryogenic-Temperature-Sensors/Pages/default.aspx

author: plesa
author_rank: Frequent Contributor
timestamp: November 08, 2014, 09:41:26 am
content: I suppose that Pt100 is good candidate.. On instruments which I used in the past was only Pt100 ( basic cryoexperiments and level sensing of LN).Check the class of the RTD ( at LN temperature can be used B with error about 1.3 K or Y (1/5B) with error about 0.8K).As insulation was used PTFE, RTD were exposed to LN, only mechanical protection needed.

author: deltawars
author_rank: Contributor
timestamp: November 08, 2014, 12:09:50 pm
content: Thanks for the information guys I find it very helpful, but I can't thank LukeW enough for the link, temperature sensors able to measure -273 Celsius and I cant believe the price I thought they would cost a lot more.
Thermocouple in Ring Terminal - Page 1
Forum section: electronics / projects

author: jones12
author_rank: Newbie
timestamp: November 14, 2018, 12:31:24 am
content: Hey guys,I'm currently working on a project and I need a bolt on thermocouple.Something like this:https://au.element14.com/labfacility/fw-j-2m/sensor-t-couple-j-washer-6mm-hole/dp/8597944I've seen heaps of them around but they're really expensive!Can I just get a standard K type thermocouple and solder it into a Lug?I'm just trying to prototype at the moment so trying to keep it cheapCheers GuysCaleb.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 14, 2018, 02:43:20 am
content: Depends on whether your measurements system cares about what the leads are tied to. You might want to insulate the TC from the lug with ceramic cement, or if the temperature is low enough, use an epoxy or thermally conductive epoxy. Or use a mica washer and insulated screw for the lug.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: November 14, 2018, 04:22:02 am
content: Think about what a type k thermocouple is and what will happen when you solder it.If filling a lug with an epoxy or something similar, there is thermal inertia to contend with. This could help to average things out. It really depends on your application and what you want to see.If you want to measure rapidly changing temperatures, then you want as little thermal mass as possible.

author: jones12
author_rank: Newbie
timestamp: November 14, 2018, 05:39:29 am
content: Cheers guys,I'm trying to make a secondary temp sensor for my car.Idea is that I'll have a sensor that bolts onto the engine block somewhere and reads the temp through an ArduinoExpoxy could work doesn't need to react quickly, would that be the best way?

author: PTR_1275
author_rank: Frequent Contributor
timestamp: November 14, 2018, 06:24:50 am
content: Ds18b20They are available in a stainless steel sleeve and should interface with Arduino already

author: DTJ
author_rank: Super Contributor
timestamp: November 14, 2018, 06:40:31 am
content: In engine development labs they routinely use 1/16" mineral insulated metal sheath (MIM) thermocouples crimped in a 3mm thick stainless washer.The washer has an oblique 1/16 hole drilled in its periphery thermocouple is poked in and the washer wacked with a punch. They are bolted to where ever they are needed.

author: duak
author_rank: Super Contributor
timestamp: November 14, 2018, 06:12:51 pm
content: I don't see why epoxy won't work. We used to epoxy thermocouples and thermistors into hex or Allen head screws and then thread those into the assemblies.Cheers,

author: N2IXK
author_rank: Frequent Contributor
timestamp: November 14, 2018, 06:55:01 pm
content: https://www.omega.com/pptst/WT.html
Thermocouple probe temperature range - Page 1
Forum section: electronics / projects

author: dritech
author_rank: Contributor
timestamp: May 05, 2024, 10:37:32 pm
content: Hi all,We are implementing a basic heating block which will reach 350oC.We intend to use the thermocouple in the link below for monitoring the temperature.The datasheet states that the temperature range is from -40 to 1100oC, but the pot seal is rated at only 200oC.Assuming the pot seal is the point where the wire enters the probe, how can this only withstand 200oC when the probe is rated at 1100oC ?We intend to drill a hole in the heating plate and fully insert the probe (pot seal will be out of the block), but still, I am sure that this part will reach more than 200oC-Is my understanding correct? If so, how can we prevent the pot seal from reaching temps which exceeds 200oC ?https://uk.rs-online.com/web/p/thermocouples/8471053?searchId=f4723c8d-98eb-49d3-b4b9-12fe4c8ea53a&gb=s

author: tooki
author_rank: Super Contributor
timestamp: May 06, 2024, 06:44:35 pm
content: Well, it’s conceivable to heat only the very tip of the probe. Stainless steel is a very poor conductor of heat (for a metal), so this is not an unusual situation.However, that probably makes this probe a poor choice for your application.

author: jonpaul
author_rank: Super Contributor
timestamp: May 07, 2024, 05:28:14 am
content: check the Omega and other temp measurement probe sites.All TC soecs, wells, etc avail for all apps and environments.Excellet handbook as well.https://www.omega.com/en-us/temperature-measurement/c/temperature-probesBon chanceJon

author: perieanuo
author_rank: Frequent Contributor
timestamp: May 07, 2024, 10:40:20 am
content: Hi, in similar case I used threaded M3 thermocouple screwed into aluminum heating plate (well, 2 cylinder heating resistors were used to heat the plate). Just position your thermocouple in a good position.If you wanna do it with your choice, use a wire terminal, those used with M3/M4 screws by pressing your thermocouple ending gently into the terminal, this will do too if you choose correctly his mounting spot and the force to keep it in the terminal at minimum needed.https://www.tme.eu/ro/details/1-320551-3/terminale-izolate/te-connectivity/
Thermocouple terminal blocks - Page 1
Forum section: electronics / projects

author: headingwest
author_rank: Newbie
timestamp: June 24, 2013, 10:22:17 am
content: Hi All,I need a hand with a thermocouple question. I've put together a small breakout board that uses K Type thermocouples. Someone using the board has mentioned that the screw terminals that the thermocouples connect to need to be specific for the type of thermocouple.My understanding is that the terminal forms a cold junction and should be close to the measuring device and that any screw terminal will do the job? Also I hopped onto digikey and couldn't find a pcb mount screw terminal for thermocouples.So - do I need specialist screw terminals?Images of the board are here:http://jimsrobot.com/thermocouple-breakout-board-ad8495Thanks for your help, Jim.

author: robrenz
author_rank: Super Contributor
timestamp: June 24, 2013, 11:59:04 am
content: AFAIK the thermocouple specific terminals and screws are for where you connect your high grade thermocouple to lower grade extension thermocouple wire. The extension wire are the same alloys just not as precise. At a "cold junction" the materials should not matter at that location. But it has to be a true Isothemal block juntion.

author: Majorstrain
author_rank: Contributor
timestamp: June 24, 2013, 12:20:51 pm
content: Yep, tell him he's dream'n.Those thermocouple connectors are for extensions. If they did them in screw terminals it would be a waste of time because your pcb tracks are not thermocouple material.Just keep your thermocouple chip close to that terminal (cold junction).Phil

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: June 24, 2013, 02:15:28 pm
content: Omega Engineering has printed circuit board!mount thermal couple sockets to transition from thermocouple wire to the copper PCB tracks. This is the point that forms the cold junction. These connectors are available with a clip for a TO-92-sized temperature sensor. Other companies make similar products that are available in small quantities – I had tracked down a source at one point but I've lost the information.These connectors are handy if you're using a T/C with connectors. If not, a standard terminal block will do if extreme accuracy isn't needed. Just put your cold junction temperature sensor as close to the terminal block as possible. The point where the T/C wires and screws make connection is the cold junction.
Thermocouples shouldn't be difficult right? - Page 1
Forum section: electronics / projects

author: Jonny
author_rank: Regular Contributor
timestamp: January 05, 2018, 07:58:56 am
content: Hey all. Let me tell you a tale of woe...So my lovely jarcar supplied solder station is now obsolete after 7yrs and my iron failed so I thought I'd gamble on an iron of same spec, looks physically the same, but from a different station and swap the plug over. Well it was a 50/50 chance. The element is same rating so all good there. The thermocouple I wouldn't have thought would be anything special but it doesn't give an ouput. My old irons thermocouple has an increasing voltage and resistance with temp and puts out around 10mV @ approx 130degC. The new one puts out 0mV and has a fixed resistance of 54ohm. Of course the controller can't work with that.What kinda thermocouple behaves like this? Or did I happen to purchase a factory dud iron that I can't return as it's now modified.Yes I wired the plug correctly

author: Kleinstein
author_rank: Super Contributor
timestamp: January 05, 2018, 08:10:43 am
content: For a thermocouple 10 mV at 130 C is allready quite a lot of voltage. It might be a type E thermocouple.https://en.wikipedia.org/wiki/Thermocouple#Nickel-alloy_thermocouples

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 05, 2018, 10:59:28 am
content: Quote from: Jonny on January 05, 2018, 07:58:56 amAssumptions.Post the brand and model of both stations so we may look things up.QuoteHow do you know it is a thermocouple? It might be a thermistor.QuoteIf you could do some more extensive measurements of resistance and voltage over temperature we could say more about it.What does it do at the operating temperatures? (350C)

author: mikerj
author_rank: Super Contributor
timestamp: January 05, 2018, 01:16:44 pm
content: A low resistance with zero voltage suggests it could be a platinum resistance thermometer. If so it's not compatible with a thermocouple interface unfortunately.

author: Jonny
author_rank: Regular Contributor
timestamp: January 05, 2018, 09:48:07 pm
content: I let it get stinking hot and resistance went to 150ohm, guess it's a thermister then. Was only a $30 gamble. Maybe I can modify the input circuit so this forms part of a resistor divider on the opamp input or something.....
Thermodo Hack - Page 1
Forum section: electronics / projects

author: MITTS
author_rank: Contributor
timestamp: June 06, 2014, 03:45:27 pm
content: I saw this the other day and I have no use for it in its current form but if it could be modified id use it all the time but not sure it would be worth it.http://developer.thermodo.comThey list accuracy of a thermistor used in the measuring circuit but I don't think that would be close to total error on something like this. Any thoughts on how accurate this device might be?For the Hack part what I'd like would to be able to plug a standard 10K ohm thermistor 12 foot long temp sensor with a standard 1/8" mono jack to replace the one they use if comparable as a input into this Thermodo and use the app they provide.Any thoughts on the hack? I see no contact info for them.
Thermoelectric Module - Page 1
Forum section: electronics / projects

author: D. Savior
author_rank: Newbie
timestamp: July 09, 2017, 02:55:50 am
content: Hi,I need help reading a datasheet.http://assets.lairdtech.com/home/brandworld/files/THR-DS-UT15,288,F2,5252%200909.pdfhttp://www.cui.com/product/resource/cp85.pdfI have spend over 2 hrs trying to determine the output voltage and current of a thermoelectric module when Delta T = 10C.My goal is to use this as a energy harvester for a project.Second question, is there some secret to reading component datasheets?When I look at a datasheet, I see many unfamiliar variables.Is there a secret online dictionary that defines these?Regards,CM

author: amspire
author_rank: Super Contributor
timestamp: July 09, 2017, 06:34:25 am
content: The datasheets do not mention the data for power generation. It would probably be disappointing. If you have a 10 degC temperature differential, you may be able to get something like 10mA at 0.5V dc. That is a guess.Get a device and test it.

author: Benta
author_rank: Super Contributor
timestamp: July 09, 2017, 08:13:55 am
content: Those are Peltier elements and not really suitable for energy harvesting. It will work, but the energy you get is negligible.You need real thermogenerator modules based on the Seebeck effect, which use the same physics, but different geometry to optimize for power generation.See here:http://www.micropelt.com/IIRC, you'll get around 1 mW of electric power for 500 mW of thermal.
Thermometer issue - Page 1
Forum section: electronics / projects

author: fedimakni
author_rank: Regular Contributor
timestamp: May 31, 2019, 05:15:59 am
content: Hello, I have this PCB I removed it from a thermometer. As you can see i don't have access to the microcontroller and i would like to let it become wireless by adding an esp32 to it. the sensor is soldered in the left side ( two pin labeled SEN) I think that the only solution to intercept the data is by connecting the lcd pin ( in the buttom side) to the esp32 but i didn't get how to do it or how the data will be ( as you can see there's no reference for the LCD. I didn't get the role of the piezo here too. Thank you.PS: no schematic or pcb layout is available on internet - I would like to stay with this solution and not doing things from scratch.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 06:21:27 am
content: Quote from: fedimakni on May 31, 2019, 05:15:59 amYes you are right that only way to get data from such highly integrated thing is to read it's LCD display signals. You have to answer yourself what you want more - read data from that LCD thermometer by all means or build wireless thermometer using esp32? In case you need just WiFi thermometer, then leave this LCD thing alone and get i2c or 1-wire temperature sensor for your esp32.One of first internet search hits from "esp32 thermometer" keywords:https://www.instructables.com/id/ESP32-E-Paper-Thermometer/QuoteIt's beeper/speaker.

author: fedimakni
author_rank: Regular Contributor
timestamp: May 31, 2019, 06:58:26 am
content: Thank you for your reply Actually I want to intercept the data from the LCD to the esp32 and then send that data vi wifi. the problem is how to connect that LCD to the esp and what kind of data will it display? ( by checking with multimeter 14 pin with no VCC or GND pin. )

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 07:23:09 am
content: First you have to learn how LCD works.Then most likely you will understand what it takes to 1) decode LCD drive signals 2) intercept them.Start here:https://youtu.be/ZP0KxZl5N2o?t=1Further readingHint: to watch & decode LCD drive signals you need oscilloscope.To illustrate how nontrivial LCD display is, here are drive waveform samples (attach) that shall be sampled and then decoded. I am not even sure that esp32 is up-to the task BTW.
Thermostat & Arduino - Page 1
Forum section: electronics / projects

author: vidarr
author_rank: Frequent Contributor
timestamp: March 12, 2024, 04:32:09 pm
content: Hi, I have these two thermostats removed from an air filter with dehumidifier and another from an air conditioner and was wondering if they can be used with an Arduino. I looked up the thermostats and just got general information, nothing technical, or datasheets.Searching Arduino forums only brings up other thermostats and hygrometers mostly sold by adafruit. It almost seems like only certain thermostats are compatible with Arduinos, but that is the question.The two I have are:VIT-300 E218405andE248681The E248681 has two sensors on it and I think one (the silver cylinder) may be for humidity, which would be great.I am finishing up a five channel relay circuit and would like to get the thermometer and hygrometer designed, built and plugged into the circuit next.Thanks!

author: brucehoult
author_rank: Super Contributor
timestamp: March 12, 2024, 10:29:35 pm
content: They are just thermistors. i.e. resistors that vary with temperature. No doubt there is a spec somewhere, but I'd just measure the resistance at room temperature (or whatever temperature points of interest you have) and make a voltage divider using a similar value fixed resistor, and measure the resulting voltage using the Arduino's ADC.

author: vidarr
author_rank: Frequent Contributor
timestamp: March 13, 2024, 11:12:42 am
content: OK, got it. So kind of like a photoresistor. This is good news. I was hoping someone wouldn't tell me I need a special driver board built for the "thermostat" ---it is a thermistor.Thank You!
These little black dip switches from Tayda are nice for prototyping. - Page 1
Forum section: electronics / projects

author: JenniferG
author_rank: Frequent Contributor
timestamp: December 08, 2022, 11:37:23 pm
content: I just received my Tayda order and these little IC shaped dip switch clusters are nice. They have normal IC pins, which are long and secure well into the breadboard unlike the red ones. They are also much smaller, but with same footprint.Great for prototyping where you perhaps need several low current toggle switches but are tight on space.35 cents a piece from Tayda :https://www.taydaelectronics.com/black-dip-switch-4-positions-gold-plated-contacts-top-actuated.html(EDIT: looks like they just went out of stock on the 4 x DIP switch cluster.. they have 3 and 5 clusters in stock though.)Here's a photo I just snapped of it in my breadboard.

author: ledtester
author_rank: Super Contributor
timestamp: December 09, 2022, 04:37:44 am
content: Years ago I regularly shopped Tayda for stuff but lately I find myself browsing aliexpress more and more. I should check them out again and see what they got.Also, it appears that you have 3D-printed some sort of "carrier board" for your stripboard and atmega2560 module. Is it anything like this:https://www.amazon.com/GeeekPi-Raspberry-Holder-Breadboard-Arduino/dp/B07WFMV8FJ/?

author: JenniferG
author_rank: Frequent Contributor
timestamp: December 09, 2022, 11:18:41 am
content: Quote from: ledtester on December 09, 2022, 04:37:44 amYeah Tayda is great for a lot of things. I really like their Royal Ohm resistors as the leads are nice and thick, great for breadboarding.I'm using this, which I 3D printed at home:https://www.thingiverse.com/thing:957376I really like it and made a little system for it I call BLOCKS:https://www.modwiggler.com/forum/viewtopic.php?t=267893

author: mikerj
author_rank: Super Contributor
timestamp: December 09, 2022, 02:38:23 pm
content: Quote from: JenniferG on December 09, 2022, 11:18:41 amThat's a genuinely neat idea, I'm going to print one out for myself. I'm often struggling with a rats nest of eval boards and small stripboard hacks when doing early development at work.