TSP

In this episode Shahriar takes a look at a faulty dry block calibrator from Ametek. These Jofra series temperature calibrators are widely used for thermostat validation as well as material analysis. This particular unit does not cool down or warm up but seems otherwise functional.
A brief set of measurements shows that one of the Peltier elements is damaged and should be replaced. A replacement is located and the temperature well is re-sealed. The unit is functional and the minimum temperature performance is verified.
Please consider supporting The Signal Path:
www.TheSignalP...
/ thesignalpath
Other links:
www.TheSignalP...
/ thesignalpath

[@xDevscom_EE]

This looks very familiar 😀 I am glad to be of a good influence to your lab... Interesting that you also got similar error about 0.4-1.0 degree, same as unit I got here.

[@Thesignalpath]

Yes! When I bought this unit I didn't realize that it didn't have the serial port... I think I figured out how to program the serial port, but sadly mine doesn't have one. I may sell this one and look for one with the serial port. We can also try to get your serial port working.

[@NiHaoMike64]

@@ThesignalpathOr figure out if there's a way to add the serial port? (Or nowadays, a USB to UART board.)

[@xDevscom_EE]

@@Thesignalpath Perhaps it's trivial to add, might just be missing RS232 chip and connector? I'll need to take mine apart to fix the fan, will take a closer look for serial port interface as well.

[@glasslinger]

I built one to test circuits. The test area is a 2 inch square flat aluminum plate. I used two stages, the hot stage being 4 peltier, 6 amp, units and the cold stage one 6 amp unit. It will get to minus 50 F.

[@originalmianos]

It would be interesting to put a non compensated crystal oscillator and a temp compensated one and compare. I think there are a few classes of tcxos as well. Even a resonator would be interesting, especially getting the temperature compensation curve.

[@TheBananaPlug]

Agreed, I came to make that suggestion and found yours. Good idea!

[@OutThere458]

What about MEMS timing devices like those from SiTime also?

[@peter.s.3207]

When you go to calibrate your dry block make sure you use a proper DIN 1/3rd PT100 probe. Type K thermocouples like you were using in the video are only accurate to +/- about 2C or so and it's likely a lot of the error you saw could have been just the probe you used

[@chrisdickens4862]

That’s very cool. I suggest you test out some different exponential converter circuits, so we can see how well they compensate for temperature.

[@MrDubje]

Would love to see a 1N827 10 ppm 6,2V zener diode in this. It should be near flat in terms of temperature response at 7,5mA.

[@andymouse]

Me too

[@ivolol]

I think for truly flat response you generally have to test currents between 5mA-10mA, but doing so should also be possible.

[@LyleHouk55]

Beings back memories I work as a boiler operator 21 years and a Boiler/ dry kiln operator for 20 years when I started work, they were using a can of water and a propane torch. enjoy all your videos

[@heathwellsNZ]

Would love to see the calibration procedure! Very interesting device. Thanks Shariar!

[@uwezimmermann5427]

suggestion for an experiment: look at the emission wavelength of a GaP green-yellow LED.

[@RB-lt8kt]

I have repaired many similar dry block calibrators by Fluke and Ametek and the only thing I can see is missing is some insulation between the heat sink and the exposed blue aluminium block. If you add the insulation which is normally a spray foam it will go down to -20. The use of 2 peltiers is cheap as looking at the size of the aluminium block I would think you need 4 peltiers as in similar size calibrators. You can build your own calibrators quite easily with fixed drilled holes for £500 or £300 for calibrators that heat from 50 to 400 degrees Celsius. You must pick the correct peltier coolers as some are limited to a maximum of 100 degrees Celsius.

[@fredflickinger643]

An adventure in thermodynamics and generating parametrics sounds good!

[@purerhodium]

We have a Peltier cooler at work hooked up to our rheometer that has been dead for months, with the same problem of all the buttons working and responding but no cooling or heating whatsoever. You've inspired me to open it up and check it, could well be a similar fix.

[@RB-lt8kt]

Also check the transistors supplying the DC voltage. These can blow sometimes.

[@gsuberland]

I'd love to see the effects of temperature on DRAM data remanence when the refresh cycle is disabled, measuring how long it takes for bit patterns to decay.

[@rolfdieterklein]

very nice device, I use peltiers very often. I use a Thorlabs PTC1/M temperature controlled breadboard (4" x 5") for experiments also using USB, instead of the cavity it uses a breadboard with M4 and M6 mounting holes. The range of course is more restricted to 4 - 45 deg C. The CTC-140A has an amazing range but thats only possible with a cavity or simular construction. Would be great to see some rf devcie experiments and charactisation using this device.

[@IanScottJohnston]

Drop in an LM399AH, connect up to your 3458A......and go cold cold cold!

[@andymouse]

Oh yes great fun can be had with this like popping voltage references in there hooking up some sort of data logger and then...Graphs !!!!!.....cheers.

[@douro20]

There are many different makers of dry block temperature calibrators but Sika developed the first in 1980. There are ones which will go all the way up to 1200C and those are sometimes used for heat treating aluminium samples in the lab.

[@Richard.Andersson]

Teflon (PTFE) has a phase transition around 18 degC, causing even the best cables and connectors to have impedance and velocity changes when going below room temperature. Could be interesting to measure.

[@OctavMandru]

Hey! That would be a great setup for testing the transistor temperature sensor based on question 14 in Jim Williams book "Innovative Linear Circuits"

[@pupperozucca4994]

wanna see an episode of Mr sign path and Mr Xdev in the same lab 🎉

[@paulcohen1555]

I had the same failure with my portable electric cooler. The accumulated moisture on the Pettie contacts is killing them. I managed to repair the connection and it functions again for many years.

[@R.Daneel]

I think it's pretty obvious: Margherita Slushi characterization.

[@SidneyCritic]

And I thought my $1000 FP1 digital manometer was DIY inside, because it was just PIC on a breadboard, ie, no PCB - lol -.

[@cda32]

Make a milkshake!

[@KA6WKE]

Being a mains-powered device, you did use an isolation transformer?

[@azkaazkiya9216]

What's the type of peltier? Is it 12706? Thanks sir

[@aliemlek]

👌👌👏👏

[@supersonictumbleweed]

If it only had a USB interface, as to run measurements from a computer

[@otherbasis8505]

Are you sure you're not running it on only one element? It's just... Peltier elements in my junk box are nowhere near 30ohms...

[@Thesignalpath]

Elements are in series. It can't run just one.

[@otherbasis8505]

​@@ThesignalpathWell, if one of the elements is 3ohm... ;)

[@Thesignalpath]

It’s not 30-Ohm. The measured resistance varies depending on the temperature and amount of current applied. This thing consumes 90-Watts when it runs, from a 21V supply. You can’t get that if the running resistance were 30-Ohms.

[@otherbasis8505]

@@ThesignalpathSure, but my point was: is the voltage drop anywhere near 50-50 between the elements?

[@Thesignalpath]

I’ll have to measure that.

[@glenj5618]

Promo_SM

[@aleksandarvasilevski7410]

Interesting video but nowhere near in details like rf videos. No view of the pcb, nothing about architecture. Things that i see missing are like adc resolution ,pwm drive circuit, signal conditioning from built in sensor....

[@Thesignalpath]

There was really nothing interesting inside. The whole thing is a relay, a MOSFET and the controller board with a micro on it. The most interesting thing was the well which I took apart.