Everyone knows how to convert from Celsius to Fahrenheit, right? On a digital thermometer you just flick the little switch, on a weather app you change the settings, or if worse comes to worse, you let Google do the math for you. But what if you want to solve the problem the old-fashioned way? Then you pull out a few op amps and do your conversions analog style.
We’ve seen before how simple op amp circuits can do basic math, and the equation that [Kerry Wong] wants to solve is even simpler. Recalling the old Tf = 9/5·Tc + 32 formula (and putting aside the relative merits of metric versus traditional units; we’ve had enough of that argument already), [Kerry] walks us through a simple dual op amp circuit to convert the 1 mV/°C output of a thermocouple module to 1 mV/°F. The scaling is taken care of by a non-inverting amplifier with resistors chosen to provide a gain of 1.8, while the offset is handled by a differential amplifier that adds 32 mV to the scaled input. Strategically placed trimmers allow [Kerry] to tweak the circuit to give just the right conversion.
For jobs like this, it’s tempting to just use an analog input on an Arduino and take care of conversions in code. But it’s nice to know how to do it old school, too, and hats off to [Kerry] for showing us the details.
At least that’s the approach that [Tom Stanton] took to his electric bike build. Having caught the electric locomotion bug on a recent longboard build, [Tom] undertook the upgrade of a cheap “fixie,” or fixed-gear bike. His delta printer was big enough for the motor mount and weather-resistant ESC enclosure, but he needed to print the drive pulley in four quadrants that were later glued together. We can’t say we hold much faith in the zip ties that transmit all the torque through the rear wheel’s spokes, but as a proof of concept it seems sturdy enough. With a throttle from an electric scooter and a battery in a saddle bag, the bike turns in pretty decent performance — at least after a minor gearing change. And everything blends in or accents the black frame of the bike, so it’s a good-looking build to boot.
Owning tools is dangerous. Once you start, there’s really no way to stop. This is clearly seen with Goran’s CNC machine. At first happiness for him was a small high speed rotary tool. He used it to drill holes in PCBs.
In a predictable turn of events, he discovered drilling tiny holes in PCBs by hand is tedious and ultimately boring. So he purchased the drill press accessory for his rotary tool.
Life was good for a while. He had all the tools he needed, but… wouldn’t it be better if he could position the holes more quickly. He presumably leafed through a now battered and earmarked Proxxon catalog and ordered the XY table.
A realization struck. Pulling a lever and turning knobs! Why! This is work for a robot, not a man! So he pestered his colleague for help and they soon had the contraption under CNC control.
We’d like to say that was the end of it, and that [Goran] was finally happy, but he recently converted his frankenmill to a 3D printer. We’ve seen this before. It won’t be long before he’s cleaning out his garage to begin the restoration and ultimate CNC conversion of an old knee mill. Videos after the break.
It seemed utter madness — people living in hot desert climates paying to heat air. At least it seemed that way to [David Thomas] before he modified his tumble dryer to take advantage of Arizona’s arid environment.
Hanging the wash out to dry is a time-honored solution, and should be a no-brainer in the desert. But hanging the wash takes a lot of human effort, your laundry comes back stiff, and if there’s a risk of dust storms ruining your laundry, we can see why people run the dryer indoors. But there’s no reason to waste further energy heating up your air-conditioned interior air when hot air is plentiful just a few meters away.
[David]’s modification includes removing the gas heating components of the dryer and adding an in-line filter. He explains it all in a series of videos, which at least for his model, leave no screw unturned. It’s not an expensive modification either, consisting mostly of rigid dryer hose and copious amounts of aluminum duct tape. He mentions the small fire that resulted from failing to remove the gas igniter, so consider yourself warned. The intake filter and box were originally intended for a house air-conditioning system, and required only minimal modifications.
This is a great build, being both cheap and easy to implement as well as being environmentally friendly without requiring a drastic change to [David]’s lifestyle. It makes us wish we had a similar endless supply of hot air.
Back in the day where the microprocessor was our standard building block, we tended to concentrate on computation and processing of data and not so much on I/O. Simply put there were a lot of things we had to get working just so we could then read the state of an I/O port or a counter.
Nowadays the microcontroller has taken care of most of the system level needs with the luxury of built in RAM memory and the ability to upload our code. That leaves us able to concentrate on the major role of a microcontroller: to interpret something about the environment, make decisions, and often output the result to energize a motor, LED, or some other twiddly bits.
Often the usefulness of a small microcontroller project depends on being able to interpret external signals in the form of voltage or less often, current. For example the output of a photocell, or a temperature sensor may use an analog voltage to indicate brightness or the temperature. Enter the Analog to Digital Converter (ADC) with the ability to convert an external signal to a processor readable value.
[Jay]’s Chevy S-10 electric conversion needed new batteries. The conversion was originally done with a bank of lead acids underneath the truck bed. With lithium battery factories so large they can boost an entire state’s economy being built, [Jay] safely assumed that it just wasn’t worth it to spend the money to replace it with a new set of the same.
You should remember the beginnings of this story from our coverage nearly a year ago. Being the kind of clever you’d expect from someone who did their own EV conversion, he purchased a totaled (yet nearly new) Nissan Leaf with its batteries intact. It took a little extra work, but after parting out the car and salvaging the battery packs for himself he came out ahead of both a new set of replacement lead acids and an equivalent set of lithium cells.
He has just completed the first test drives with the conversion, having built 48 Leaf cells into blocks resembling the volumes the old batteries occupied. He had to add some additional battery management, but right-off-the-bat, the conversion netted him more amps and 650lbs (295kg) less weight for the same power. Nice!
We linked to all the posts tagged leaf on [Jay]’s blog. There’s a lot going on, and the articles aren’t all linked to each other. It’s a really cool build and there are definitely tricks to learn throughout the whole process. If you have an hour to kill, [Jay] recorded the entire 26-hour process in a 66-minute video that is embedded below. It’s fun to watch him build up and mount the different modules and gives you a deep appreciation for his devotion to the project.
He located the service manual for the camera and got busy taking it apart. He had to desolder the main board to get to the CCD block, where the sensor, IR cut filter, and the shake reduction motors are all located. The IR cut filter was pried off without too much trouble as it is only secured with a clip and an adhesive foam gasket.
Once things were disassembled, the real work began. He had a little trouble cutting the IR filter he purchased, so it took a little bit of elbow grease to get things exactly the way he wanted. Once he got the filter in place, he carefully re-mounted the sensor block to ensure that it was set at the proper height.
Once things were fully reassembled, he tried taking a few test shots, but found that there were some focus issues due to the IR filter being thicker than the original IR cut filter. A few manual tweaks in the camera’s debug menu and he was in business.
Be sure to check out his photo stream to take a look at some of the pictures he snapped with his new IR camera.