Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

[mansaxel]

This 4 wire meas explanation

https://learn.adafruit.com/adafruit-max ... ds-2928771

is not what I was expecting (I mean)
Datasheet MAX31865

https://cdn-learn.adafruit.com/assets/a ... X31865.pdf

bah....

Anyone with experience with PT100 and PT1000 in 180-450C° range? What is best PT100 or PT1000 if both in 4 wire setup?
Learning mode on...

Ciao!

Isn't it better with Type K thermocouple sensors here? Or are you constrained by Circumstances? Seems that there are interface boards from Adafruit for thermocouples too (going on the simplistic assumption that the place you linked to has something to do with your application). Having played with my Model 51 Fluke thermometer and obtaining excellent results with cheap thermocouples from overseas, I am hard pressed to understand why one would want thermistors.

All my steaks are thermocoupled!

[Robert]

This 4 wire meas explanation

https://learn.adafruit.com/adafruit-max ... ds-2928771

is not what I was expecting (I mean)
Datasheet MAX31865

https://cdn-learn.adafruit.com/assets/a ... X31865.pdf

bah....

Anyone with experience with PT100 and PT1000 in 180-450C° range? What is best PT100 or PT1000 if both in 4 wire setup?
Learning mode on...

The Adafrut description is wrong.
The wire resistance error is proportional to current. The energising current (force on Maxim datasheet) is carried on one pair of wires and as it's current voltage drop dos not matter. The voltage is measured on the second pair with a high imedance input so current and voltage drop is insignificant. I'm sure that is what you expected.
Don't beleive all you read on the web. There are lots of "experts" on all subjects spouting rubbish.

[mnementh]

This 4 wire meas explanation

https://learn.adafruit.com/adafruit-max ... ds-2928771

is not what I was expecting (I mean)
Datasheet MAX31865

https://cdn-learn.adafruit.com/assets/a ... X31865.pdf

bah....

Anyone with experience with PT100 and PT1000 in 180-450C° range? What is best PT100 or PT1000 if both in 4 wire setup?
Learning mode on...

Ciao!

Isn't it better with Type K thermocouple sensors here? Or are you constrained by Circumstances? Seems that there are interface boards from Adafruit for thermocouples too (going on the simplistic assumption that the place you linked to has something to do with your application). Having played with my Model 51 Fluke thermometer and obtaining excellent results with cheap thermocouples from overseas, I am hard pressed to understand why one would want thermistors.

All my steaks are thermocoupled!

My guess would be when you want a really tiny mass for quick thermal equalization; you can easily make a microscopic thermistor using semiconductor fab tech. All the insta-read food thermometers I've ever owned are thermistor-based and sensor housed in a super-thin needle probe.

Yes, I get that has very little to do with the metrology-oriented rabbit-hole discussion at hand... just an observation.

mnem

[Zucca]

Isn't it better with Type K thermocouple sensors here? Or are you constrained by Circumstances? Seems that there are interface boards from Adafruit for thermocouples too (going on the simplistic assumption that the place you linked to has something to do with your application). Having played with my Model 51 Fluke thermometer and obtaining excellent results with cheap thermocouples from overseas, I am hard pressed to understand why one would want thermistors.

Hej min vän!

https://blog.ashcroft.com/rtd-vs-thermo ... er%20time.

2022-12-02 08_45_33-Window.png

I am not an expert on T measurement at all but it seems legit, moreover in RTD you do not have to deal with Seebeck effect...
So you can safely solder whatever you want... where you want. In thermocouple attention is required, at the solder joint you will have a Seebeck effect too...

quick google search example
https://electronics.stackexchange.com/q ... etween-a-p

[Zucca]

Don't beleive all you read on the web. There are lots of "experts" on all subjects spouting rubbish.

Thanks Rob, you read my mind. I will try to contact Adafruit to correct it. That said in the 3 wire configuration they are somehow right, the ADC remove the imaginary drop on the negative wire supposing it is the same with what was measured in the positive wire.

[Robert]

Don't beleive all you read on the web. There are lots of "experts" on all subjects spouting rubbish.

Thanks Rob, you read my mind. I will try to contact Adafruit to correct it. That said in the 3 wire configuration they are somehow right, the ADC remove the imaginary drop on the negative wire supposing it is the same with what was measured in the positive wire.

While you could do it through calculation (I don't know any instrument that does) the 3 wire connection was devised for classic bridge circuits. These two links explain. The Omega one expalis but does not have a good diagram.
https://www.omega.com/en-us/resources/r ... onnections
https://www.kyowa-ei.com/eng/technical/ ... iring.html

Note that this only works close to bridge balance so the input has to be optimised for the temperature range. Typically around 0 degrees C.

450 degrees C is a bit high for a Pt sensor you would certainly use a 100 Ohm one not a 1000 Ohm. Need to make sure the cable is rated high enough.
Thermocouples would be more usual for this temperature range, typically type K.

[Zucca]

While you could do it through calculation (I don't know any instrument that does)

From the datasheet....

A 3-wire connection is a compromise approach that
uses one less conductor than the 4-wire approach. To
compensate for the voltage drop across the return wire,
the voltage between FORCE+ and RTDIN+ is subtracted
from (RTDIN+ - RTDIN-). This is accomplished using the
FORCE2 sampling input. If the cable resistances are wellmatched, the error due to cable resistance is cancelled.
Select 3-wire operation by setting the 3-wire bit in the
Configuration register to 1.

hard to tell what they are doing, but subtracted is pointing to a calculation... who knows....

Thank you so much for the hint about the high temp and PT1000, you are right, I will go 4 wire with PT100. Bingo!
It is always so easy once the brain finally understand...

[Robert]

I do now.....

[mansaxel]

All my steaks are thermocoupled!

My guess would be when you want a really tiny mass for quick thermal equalization; you can easily make a microscopic thermistor using semiconductor fab tech. All the insta-read food thermometers I've ever owned are thermistor-based and sensor housed in a super-thin needle probe.

Possibly. However that does not seem to reflect in my observations; the Fluke 51 with no-name Chinesium furnace-style thermocouples consistently outperforms purpose-built thermistor sensor-meter combination in culinary work. It is faster and more reliable in measurements. Also, it calibrates to within 0,5° C out of the box, without adjustment. I don't trust my ghetto-fab ice baths and boiling water to more than that.

[mansaxel]

I am not an expert on T measurement at all but it seems legit, moreover in RTD you do not have to deal with Seebeck effect...

Oh, indeed, using thermocouples has its drawbacks. What is normally done to minimise the bad effects is a set of practices;

- no dissimilar junctions on the wire -- hence the special thermocouple connector, made of proper materials

- First Seebeck-sensitive junction to be inside the meter, where a thermistor (!) can be used to compensate for the effect.

[mnementh]

All my steaks are thermocoupled!

My guess would be when you want a really tiny mass for quick thermal equalization; you can easily make a microscopic thermistor using semiconductor fab tech. All the insta-read food thermometers I've ever owned are thermistor-based and sensor housed in a super-thin needle probe.

Possibly. However that does not seem to reflect in my observations; the Fluke 51 with no-name Chinesium furnace-style thermocouples consistently outperforms purpose-built thermistor sensor-meter combination in culinary work. It is faster and more reliable in measurements. Also, it calibrates to within 0,5° C out of the box, without adjustment. I don't trust my ghetto-fab ice baths and boiling water to more than that.

Not on the grill. You will be a crispy critter long before that stabilizes, unless you put it on a half meter stick; I know because I've done it with my Fluke and that's what it took. A good instant-read meat thermometer stabilizes in 1.5ish seconds, and extended it puts your hand ~300mm or more above the meat. Even at 1.5 seconds, you will often find yourself wishing for a Orka mitt unless you have dwagon hide, especially if yer BUT (Burger Under Test ) has a flareup.

I understand that the temp on those is at best "a good estimate"... but in all reality, as long as you're within a couple degrees science either way, you're gonna be fine. Nobody's recipe for anything on the grill is less than 5-10 degrees above the safe range for whatever meat, which exceeds necessary dwell time at the magic number several times over. This isn't rocket chemistry.

mnem
*tssssssst....*

[Zucca]

PC dump saga,

RAM installed, pass POST (Power On Self Test) on LED Diagnostic level (solid LED white on the power button)... but no image on monitor.

from service manual:

Power-supply unit Built-in Self Test (BIST)
XPS 8930 supports a new power-supply unit Built-in Self Test (BIST). BIST can now be performed by connecting the power cord to the
power-supply unit.
1.
Turn off your computer.
2.
Disconnect the power cord from the power-supply unit, and wait for 15 seconds.
3.
After 15 seconds, connect the power cord to the power-supply unit.
•
If the LED is on for 3 seconds and turns off, it indicates that the power-supply unit is functional. Continue with troubleshooting
steps for other devices.
•
If the LED does not turn on, it indicates a hardware failure.

LED does not turn on.... I hear you guys laughing....

[mansaxel]

Not on the grill. You will be a crispy critter long before that stabilizes, unless you put it on a half meter stick; I know because I've done it with my Fluke and that's what it took. A good instant-read meat thermometer stabilizes in 1.5ish seconds, and extended it puts your hand ~300mm or more above the meat. Even at 1.5 seconds, you will often find yourself wishing for a Orka mitt unless you have dwagon hide, especially if yer BUT (Burger Under Test ) has a flareup.

I understand that the temp on those is at best "a good estimate"... but in all reality, as long as you're within a couple degrees science either way, you're gonna be fine. Nobody's recipe for anything on the grill is less than 5-10 degrees above the safe range for whatever meat, which exceeds necessary dwell time at the magic number several times over. This isn't rocket chemistry.

mnem
*tssssssst....*

I think we have different experiences;

• My food meters are slow! And cheap. I think they're even deliberately so.
• When I cook over fire with thermometer, it's mostly with an embedded probe; think a somewhat bigger roast on low-and-slow working, with a "permanent" probe. Slow response is not an issue here. But having a metal screened probe with a heat resistant steel braided cable is really nice. Threaded-insert HVAC thermocouples are a nice solution to this.

Perhaps I should snatch the testo IR meter I bought used for next to nothing, back from wifes leopard gecko habitat work, and try that.

[mansaxel]

PC dump saga,

RAM installed, pass POST (Power On Self Test) on LED Diagnostic level (solid LED white on the power button)... but no image on monitor.

from service manual:

Power-supply unit Built-in Self Test (BIST)
XPS 8930 supports a new power-supply unit Built-in Self Test (BIST). BIST can now be performed by connecting the power cord to the
power-supply unit.
1.
Turn off your computer.
2.
Disconnect the power cord from the power-supply unit, and wait for 15 seconds.
3.
After 15 seconds, connect the power cord to the power-supply unit.
•
If the LED is on for 3 seconds and turns off, it indicates that the power-supply unit is functional. Continue with troubleshooting
steps for other devices.
•
If the LED does not turn on, it indicates a hardware failure.

LED does not turn on.... I hear you guys laughing....

Now, you had to put money somewhere to boot. Yes, it pays to RTFM, and Chinesium caps in PSU are realistically that which we can fix ourselves in modern PCs. (without resorting to a Rossman bodge)

[Specmaster]

Just come across this of Facebook today, really fascinating.

https://www.youtube.com/shorts/U_3e0vYkg-s

[bitseeker]

Wifey & kids keep snurching my medium & small spring clamps to put on cereal & chip bags... and then they vanish. I literally go to Horror Fraught every few months to buy more.

mnem
clamps.jpeg

Here, we've got special Devices for this:



This is IKEA BEVARA ("keep") bag clamps. Get a couple bags of these. They can clamp a plastic bag air tight without breaking a sweat.

I got some of those, too. However, most of the time, binder clips do that job and many other "hold stuff" tasks around the house.

[bitseeker]

The THD+N at 1000 hz at 1 volt (top) and 5 volts (bottom) isn't catastrophically bad but not as good as it could be, I think, so I'm going to let it run overnight and see if or how it changes by lunchtime tomorrow per the suggestions in one of Simon Spier's videos while I work on the other stuff I have going.

My HP 8903B readings after not quite 12 hours on have changed slightly. No filter readings are the same, or slightly worse, and filtered readings have improved a bit.

Initial Current Delta Configuration
0.0068 0.0071 +0.0003 1 kHz @ 1 V, no filter
0.0028 0.0024 -0.0004 1 kHz @ 1 V, 80 kHz low pass
0.0038 0.0038 0 1 kHz @ 5 V, no filter
0.0023 0.0019 -0.0004 1 kHz @ 5 V, 80 kHz low pass

-Pat

Eidt - in my draft, the above was spaced out in a nice table. Apparently the formatting doesn't carry over to the actual post.

Previously, I added bbCode for HTML table elements. The codes are the same as the HTML element names, just in bbCode format.

Code: Select all

[table]
[tr][th]Initial[/th][th]Current[/th][th]Delta[/th][th]Configuration[/th][/tr]
[tr][td]0.0068[/td][td]0.0071[/td][td][color=#FF0000]+0.0003[/color][/td][td]1 kHz @ 1 V, no filter[/tr]
[tr][td]0.0028[/td][td]0.0024[/td][td][color=#00BF40] -0.0004[/color][/td][td]1 kHz @ 1 V, 80 kHz low pass[/tr]
[tr][td]0.0038[/td][td]0.0038[/td][td]0[/td][td]1 kHz @ 5 V, no filter[/tr]
[tr][td]0.0023[/td][td]0.0019[/td][td][color=#00BF40] -0.0004[/color][/td][td]1 kHz @ 5 V, 80 kHz low pass[/tr]
[/table]

Initial	Current	Delta	Configuration
0.0068	0.0071	+0.0003	1 kHz @ 1 V, no filter
0.0028	0.0024	-0.0004	1 kHz @ 1 V, 80 kHz low pass
0.0038	0.0038	0	1 kHz @ 5 V, no filter
0.0023	0.0019	-0.0004	1 kHz @ 5 V, 80 kHz low pass

Note: I had to add some CSS to the current theme to make the table look good. If the contents of the table looks squished together, try force-reloading the page in your browser so it re-fetches the CSS.

[mnementh]

PC dump saga,

RAM installed, pass POST (Power On Self Test) on LED Diagnostic level (solid LED white on the power button)... but no image on monitor.

from service manual:

Power-supply unit Built-in Self Test (BIST)
XPS 8930 supports a new power-supply unit Built-in Self Test (BIST). BIST can now be performed by connecting the power cord to the
power-supply unit.
1.
Turn off your computer.
2.
Disconnect the power cord from the power-supply unit, and wait for 15 seconds.
3.
After 15 seconds, connect the power cord to the power-supply unit.
•
If the LED is on for 3 seconds and turns off, it indicates that the power-supply unit is functional. Continue with troubleshooting
steps for other devices.
•
If the LED does not turn on, it indicates a hardware failure.

LED does not turn on.... I hear you guys laughing....

Good on ya fer coming back and admitting it.

Yeah, except no LED on unit could be either PSU dead or a fault on the PC. Does your particular one have a LED on the PSU on the back?

Alternately, anybelly who works on more than two PCs in their life should have one-a-deez:



You want one like this, with the digital display and in particular the PG segment. That monitors the time between application of power and the time the PSU finishes its POST and sends a signal out to the PG pin, and gives back a number in mS. 180-280 is excellent, 280-320mS is okay, and it will fail out at somewhere around 350mS IIRC... Concept is that if it takes too long to return a PG signal, that means it is struggling to charge the final output caps or regulation failure in the PSU. These will provide enough of a load to keep the PSU from shutting down due to no-load condition, but not near enuf for a proper load test... unless you mod the pluck out of them.

Typical cost is $10-15 from slAmazon, $20-25 from a brick & mortar. Here's one at $10 with Monday delivery:

https://www.amazon.com/Comidox-Computer ... 07J9LRC6T/

mnem
*juicy*

[Specmaster]

Oh hell yes, those power supply testers are a godsend, so much information at the same time, never regretted getting mine, a vital part of my PC toolkit.

tester.jpg

[mnementh]

Not on the grill. You will be a crispy critter long before that stabilizes, unless you put it on a half meter stick; I know because I've done it with my Fluke and that's what it took. A good instant-read meat thermometer stabilizes in 1.5ish seconds, and extended it puts your hand ~300mm or more above the meat. Even at 1.5 seconds, you will often find yourself wishing for a Orka mitt unless you have dwagon hide, especially if yer BUT (Burger Under Test ) has a flareup.

I understand that the temp on those is at best "a good estimate"... but in all reality, as long as you're within a couple degrees science either way, you're gonna be fine. Nobody's recipe for anything on the grill is less than 5-10 degrees above the safe range for whatever meat, which exceeds necessary dwell time at the magic number several times over. This isn't rocket chemistry.

mnem
*tssssssst....*

I think we have different experiences;

• My food meters are slow! And cheap. I think they're even deliberately so.
• When I cook over fire with thermometer, it's mostly with an embedded probe; think a somewhat bigger roast on low-and-slow working, with a "permanent" probe. Slow response is not an issue here. But having a metal screened probe with a heat resistant steel braided cable is really nice. Threaded-insert HVAC thermocouples are a nice solution to this.

Perhaps I should snatch the testo IR meter I bought used for next to nothing, back from wifes leopard gecko habitat work, and try that.

When I grill it's usually covered with meat... a dozen burgers, 'nuther dozen dogs minimum. Maybe as few as a half-dozen steaks, but those are usually accompanied by sausages plus some baked taters and/or corn and/or rolls cut open to toast and catch some smoke. A good insta-read thermometer is kindof paramount for that; you need to be able to check all the meat on the the surface quickly, especially if yer coming up on time for a flip. I have several remote-probe leave-in thermometers for slow-cooking thick cuts in both oven and grill.

IR thermometer will tell you the temp of the grates (good for searing), even that of the top of a large cut of meat (small cuts like dogs and burgers, the superheated air can fuck with it's pee-weeny little brain) but not much use for what's important: the internal temp of the thickest part of what yer cooking.

mnem

[Specmaster]

Solved the problem with those triangle sanding pads that fit onto multi-tools, despite the manufacturer advising me to alternate heads every 5 to 10 minutes to allow the head and sanding pads to cool down as the heat causes the hooks on the heads to breakdown / melt and as a result the sanding pads are no longer gripping the Velcro, therefore slipping off the heads

Buy some genuine Velcro from Amazon, 100mm wide in 1 metre lengths, sand the fake Velcro, off the sanding heads and leave them smooth, cut the genuine Velcro to fit the head, cut some holes in it to allow the suction to extract the dust, and a large hole in the middle to access the fixing screw. Peel the backing paper off the Velcro and stick the new Velcro on the head. Problem solved, done loads of sanding today, using the same head all the time, sanding pad does no longer slips about and allows the use of all the grit, before they were being junked with loads of grit left, but no grip.

Also brought some large sheets of sanding paper designed for Velcro heads, cut some new pads from the sheets, 2 of the holes are already in the right locations, leaving a further 4 holes to be made. Tomorrow I have a set of leather hollow hole punches arriving, so will punch the remaining holes in the pads and make up some smaller finger pads for smaller areas of detailing.

I will come and advise how that goes tomorrow.

sanding.jpg

[mansaxel]

When I grill it's usually covered with meat... a dozen burgers, 'nuther dozen dogs minimum. Maybe as few as a half-dozen steaks, but those are usually accompanied by sausages plus some baked taters and/or corn and/or rolls cut open to toast and catch some smoke. A good insta-read thermometer is kindof paramount for that; you need to be able to check all the meat on the the surface quickly, especially if yer coming up on time for a flip. I have several remote-probe leave-in thermometers for slow-cooking thick cuts in both oven and grill.

IR thermometer will tell you the temp of the grates (good for searing), even that of the top of a large cut of meat (small cuts like dogs and burgers, the superheated air can fuck with it's pee-weeny little brain) but not much use for what's important: the internal temp of the thickest part of what yer cooking.

Yes, in that application the fast one is essential. I "starve" the family (not really) so for burgers people get one, sausages is different. For the hard-to-judge bits like a full row of entrecôte or a whole roast beef, the slow thermocouple is adequate and good.

[mnementh]

Low & slow is the only way to cook a prime rib... preferably indirect heat from a hickory fire with some mesquite chips to smoke in the convection path.

mnem

[Cerebus]

Low & slow is the only way to cook a prime rib... preferably indirect heat from a hickory fire with some mesquite chips to smoke in the convection path.

mnem

Tsk, tsk. Speaking as un rosbif* there is only one proper way to roast beef - to spitroast it in front of a wood fire thusly:



This is sadly now near impossible due to the disappearance of the Turnspit or Turnespete breed of dog. Modern social morés have made the use of the natural alternative, a small child, impractical, as the whipping necessary to properly concentrate the child's attention on the task at hand, and ensure the diligent execution thereof is nowadays frowned upon.

*To be nicknamed after a culinary dish by the French, a country with a fierce reputation for culinary excellence, is not as often stated done in mockery but is in fact a tip of the hat to the one bit of cooking that they felt at the time we did better than them. Of course the French have over the years come to a realisation that many English things, food and otherwise, are superior hence their introduction of so many English terms into their language: Sandwich, Weekend, Smartphone, personal hygiene and so on.

[mnementh]

I'm sure you could do both.

While I can understand the desire for a show with your meal (motivating a small child is an engaging pastime, to say the least ); we have indirect-heat smokers with a mechanized spit that are designed to remove the need for such diversions, making the small child now a completely optional equipment.

This allows one to concentrate on better diversions, like conversation with friends and tickling the innards of electronics.

Either way, the important takeaway is still low & slow with indirect heat from a nice smoky wood fire FTW.

mnem