Todays fun with TE: Temperature logging, the hardware side:
Starting with the less related (but still needed) stuff, here we the mighty database server:
(Yes it's the credit-card sized thing with the blue cable)
running the time series database (QuestDB) and the "observability platform" (Grafana) on an OrangePi
(the once cheaper and more powerfull asian nephew to the RaspberryPi) with a whopping 128GB of SD card storage.
It's mostly idle but using ~60% of its 1GB of ram.
Onto greener pastures, this mess of cables should allow logging without blocking the whole desk:
We have in red the temperature chamber itself, in blue the chinese TCB-NE peltier element controller.
(at first ~100€ seems steep, but "the next best thing" is ~500€
)
It is supplied with 13.3V from a SMPS (orange), but it is a (clever but simple) buck-based topology anyway.
The DUT (a voltage reference) is supplied by a linear supply (green) and finally measured by the DMM (light blue).
The whole shebang is run by a python script on a 13" Thinkpad to the left.
I'll post a photo of that, once the script is out of the initial "soak and stabilize" phase and
we can see some status messages regarding the ramping.
Finally here is the data collected so far:
Green trace - DUT voltage drift while equalizing its temperature to the chamber.
The yellow trace - temperature of the chamber wall reported by the peltier controller gizmo -
is nicely wiggeling around +-1LSB, give or take. The autoscaling should behave much better once the ramping has started.
The cable runs are not optimal (not enough space between power and measurement side for my liking), but it is what it is for now.
Also, the cooling fan on the peltier is emphasizing the need for future migration...
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