In an era where we can see the current temperature with just a glance at our smartphones, the classic “Time and Temp” gadget sitting on the desk doesn’t have quite the same appeal. The modern weather fanatic demands more data, which is where this gorgeous full-day temperature display from [Richard] comes in.
The display, built inside of a picture frame, shows the temperature recorded for every hour of the day. If the LED next to the corresponding hour is lit that means the value displayed is from the current day, otherwise it’s a holdover from the previous day’s recordings. This not only makes sure all 24 LED displays have something to show, but gives you an idea of where the temperature might be trending for the rest of the day. Naturally there’s also a display of the instantaneous temperature (indoor and outdoor), plus [Richard] even threw in the current wind speed for good measure.
In the video after the break, [Richard] briefly walks us through the construction of his “Thermo Logger”, which reveals among other things that the beautiful panel art is nothing more exotic than a printed piece of A4 paper. The video also features a 3D model of the inside of the device which appears to have been created through photogrammetry; perhaps one of the coolest pieces of project documentation we’ve ever seen. We’ll just throw this out there: if you want to ensure that your latest build makes the front page of Hackaday, pop off that back panel and make some decent quality 3D scans.
In Alaska, the impact of climate change is easy to see. Already the melting permafrost is shifting foundations and rocking roads. Hotter summers are also turning food caches from refrigerators into ovens.
The Alaska Datalogger carried a pretty serious list of requirements. It has to be waterproof, especially as ice and snow turn to water. Ideally, it should sip power and have a long battery life anyway. Most importantly, it has to be cheap and relatively easy for kids to build.
This awesome little data spaceship is designed around an O-ring used in domestic water purifiers. The greased up O-ring fits between two 3D printed enclosure halves that are shut tight with nylon bolts. Two waterproof temperature probes extend from the case—one inside the cache and the other outside in the elements. It’s built around an Adafruit Feather Adalogger and powered by an 18650 cell. The data is collected by visiting the site and pulling the SD card to extract the text file. There’s really no other way because the sites are far out of cell coverage. Or is there?
Hacking and tinkering are always fun and games, but one just has to appreciate when all efforts are additionally aimed towards doing something good. [Nikos] sets an example by combining his interest in technology with his passion for wildlife conservation by creating a low cost and ultra-low power temperature logger — and he is using a coin cell for it.
As the founder of a sea turtle conservation project in Greece, [Nikos] enjoys building scientific instruments that help him and his team on their mission. With a goal to log the temperature every 10 minutes over a period of at least 180 days, he designed a PCB just big enough to hold a CR2032 coin cell. Fifty of them will eventually be sealed in waterproof enclosures, and buried in the sand for the whole research duration.
Limiting the design to its bare necessities, the rest of the PCB is housing a digital temperature sensor, an SPI EEPROM to hold all the recorded sensor values over those 180 days, and an ATmega328PB clocked by a 32.768kHz crystal. Wondering what to do with all the extra, unused pins of the ATmega, [Nikos] simply routed them to be accessible through pin headers, thus turning the data logger alternatively into a coin cell powered development board.
Assuming your logging interval requirements are significantly lower, you might be thrilled to hear that [Nikos] estimates a theoretical 7+ years an average coin cell could power the data logger in sleep mode, which makes him confident to reach the 180 days goal.
Coin Cell Challenge
Build something cool powered by a coin cell, win prizes!
How long can you keep an Arduino circuit running on three AA batteries? With careful design, [educ8s] built a temperature sensor that lasts well over a year on a single charge of three 2250 mAH rechargeable cells (or, at least, should last that long).
Like most long-life designs, this temperature sensor spends most of its time sleeping. The design uses a DS18B20 temperature sensor and a Nokia 5110 LCD display. It also uses a photoresistor to shut off the LCD display in the dark for further power savings.
During sleep, the device only draws 260 microamps with the display on and 70 microamps with the display off. Every two minutes, the processor wakes up and reads the temperature, drawing about 12 milliamps for a very short time.
Along with the code, [educ8s] has a spreadsheet that computes the battery life based on the different measured parameters and the battery vendor’s claimed self discharge rate.
[Daniel Klien] sent me his thermd environmental monitoring project. It’s written in perl, but the cool part is the sheer number of supported devices. It’s pretty rare when a single developer is given test hardware so he can add support for it.
Sure, this isn’t a hardware hack, but temperature logging is one of those irritating problems of hardware hacking. I’ve got loads of uses for it – coffee roasting, house management, battery charging, monitoring for my EV motorcycle project.