If you’re reading a thermocouple with one of those fancy schmancy SPI thermocouple amplifiers, this one isn’t for you. If, however, you’re still going through those old-school analog thermocouple amplifiers like the AD595, [miceuz] has just the thing for you. He’s come up with a library for embedded devices that reads the temperature of a k-type thermocouple with +- 0.03°C of accuracy.
As with anything dealing with natural phenomena, the voltage generate by the bimetallic junction of a thermocouple probe is decidedly non-linear. This is a problem when dealing with embedded devices, as that would mean using floating point arithmetic, greatly increasing the amount of code. [micuez] found the NIST tables for a K-type thermocouple and interpolates the actual temperature of the thermocouple probe from the NIST data. The usual way of measuring thermocouples – a polynomial unction of some sort – has an error of about 0.06°C. [miceuz]’s library has an error of less than half that, all while using less code.
The library doesn’t support temperatures below zero, but this is still a work in progress. Still, if you’re looking for a very accurate library for a forge, crock pot sous vide build, or a toaster oven reflow controller, you can’t do better than [miceuz]’s work.
On Hackaday, we usually end up featuring projects using building blocks (components, platforms…) that can be bought on the market. We however don’t show many hacks that rely on basic physics principles like the one shown in the picture above.
In the video embedded below, [nylesteiner] explains that copper oxide can be formed when heating a copper wire using a propane flame. When two oxidized wires are placed in contact with each other, an electrical current is produced when one wire is heated much hotter than the other. The trade-off is that the created thermocouple generates a small voltage but a ‘high’ current. However, when you cascade 16 junctions in series you can generate enough voltage to light up an LED. Even though the complete system isn’t particularly efficient at converting heat into electricity, the overall result is still quite impressive in our opinion. We advise our readers to give a look at [nylesteiner]’s article and blog to discover his interesting adventures.
Continue reading “Copper Oxide Thermoelectric Generator Can Light An LED”
For some reason or another, the Hackaday tip line sometimes sees a short burst of submissions for the same project. The latest one of these was for toaster oven reflow stations. They’re both great builds and different approaches to making a useful tool out of home appliances.
First up is [Richard]’s build. he ended up with a fairly high-end build using a Rocket Scream Reflow Oven Controller Arduino shield. This shield accepts a normal K-type thermocouple and controls an external solid state relay with the Arduino’s PID library. [Richard]’s build has a few neat additions – a properly dremeled enclosure, computer fan, and a welding blanket for insulation. Now that we think about it, it’s odd we’ve rarely seen any sort of insulation in these reflow oven builds.
Next up is [Ray]’s version of a Black & Decker reflow oven. While not as fancy as [Richard]’s build, this one does have a few features that make it very interesting. Instead of messing around with thermocouples, [Ray] simply took a digital kitchen thermometer – a neat tool that already a thermistor in a compact metal probe – and read the analog value with an Arduino. To control the power, [Ray] is using a cheap 433 MHz radio transmitter to control a few remotely operated power sockets. It’s a very clever and inexpensive replacement for a SSR, especially since [Ray] had these power sockets just lying around.
So there you go. The same tool, built two different ways. A great demonstration of how you can not only build anything, but you can build anything any way you want.
We don’t know how [Ben Krasnow] gets his hands on so much cool hardware. This time around is a bit of vintage tech: a thermocouple vacuum gauge.
The part seen above, and represented in the schematic, is the sensor side of things. This is interesting enough by itself. It has an air chamber with an electric heater element in it. When air is present it dissipates the heat, when under vacuum the heat builds and causes the thermocouple to generate some voltage on its connections.
Keep watching his presentation and things get a lot more interesting. The original unit used to measure the sensor is a throwback to the days when everything had sharp corners and if you were running with scissors you’d eventually teach yourself why that’s not such a good idea. The designers were rather cavalier with the presence of mains voltage, as it is barely separated from connections grounding the case itself.
Want to see some of the other cool equipment he’s got on hand? How about a CT scanner he built.
Continue reading “Thermocouple vacuum gauge teardown”
When working with chemical reactions it may be necessary to test the purity of the components you’re using. This is especially true with hobby chemists as they often acquire their raw materials from the hardware store, garden center, or pool supply. [Ken] figured out how to get around the $500 price tag of a commercial unit by building this DIY melting point test apparatus.
In this image he’s using a thermocouple to monitor the temperature of the melting surface, but mentions that you can do this with an inexpensive dial thermometer and will still have great results. That melting surface is the hexagonal head of a bolt which he drilled out to provide a concave surface for the test compound. Inside the PVC pipe is the heating element from a 40W hot glue gun. He wrapped it in fiberglass fabric which is sold in the plumbing supply to protect the area around pipe joints during soldering. The rotary light dimmer feeds the electricity to the element, allowing for adjustments to the ramping speed.
Whether you take it as a single shot or a double, a great Barista want’s to know the details on what’s happening with the espresso machine. [Tobi] was happily generating the morning cup when he realized that the needle-thermometer on his machine wasn’t working any longer. Instead of shelling out a lot of money for a direct replacement, he built his own display and controller for this espresso machine (translated).
He had a few goals with this hack. Obviously he needed to replace the temperature meter, but he also wanted a colorful display and some timing options. He was able to get his hands on a nice little OLED display that would fit in the vacated opening and it only cost a few bucks. He’s got his own mini-mill which came in handy when fabricating a board to host the ATmega16 which drives add-on, but he also used it to make a bracket for the screen replacement.
Now his machine is fixed, looks a bit more modern, and it has more features which are shown off in the video after the break. If you’re looking to add some custom circuitry to your coffee ritual you may also take some inspiration from this similar espresso machine hack. Continue reading “Espresso upgrade gives you more data with your caffeine”
Since we are in the midst of featuring a wide assortment of ATtiny hacks, [Kenneth] wrote in to share a project he has been developing over the last few months, the SerialCouple.
Most all development platforms have the ability to function as an analog to digital converter, but you don’t always need a full-featured board when all you require is serial output for your computer. With his SerialCouple board, [Kenneth] is trying to take some complexity out of the process by building a standalone thermocouple ADC board. The SerialCouple is designed to take analog readings from a thermocouple, converting them to digital values that can be sent to any device over a serial connection. The grunt work is done by a Maxim MAX31855 chip, which converts the thermocouple’s analog data to digital temperature readings. The digital representation of the temperature is then retrieved by the on-board ATtiny2313, which sends the data out the serial port.
If a standalone thermocouple ADC board is something you’ve been looking for, be sure to swing by his site to take a look at his code and schematics.
Continue reading to see a short video demo that explains how the SerialCouple works.
Continue reading “ATtiny Hacks: SerialCouple – A standalone thermocouple ADC board with serial out”