One of the big stories last week was the announcement of results from clinical trials that suggest a new COVID-19 vaccine developed through the joint effort of the American and German companies Pfizer and BioNTech is strongly effective in providing immunity from the virus. In the midst of what is for many countries the second spike of the global pandemic this news has been received with elation as well as becoming the subject of much political manoeuvring.
While we currently have two vaccine candidates with very positive testing results, one of the most interesting things for us is the need to keep doses of the Pfizer/BioNTech vaccine extremely cold until they are administered. Let’s dig into details of the refrigeration problem at hand.
Continue reading “The Special Fridges Behind The COVID-19 Vaccine, Why It’s Surprisingly Difficult To Be That Cool”
[Mitsuru Yamada] states that one of the goals for this 6502 computer build was to make it strong enough to survive real-world usage. In that regard alone we’d call this a success; the die-cast aluminum enclosures used are a little blast from the past and lend a nice retro industrial look to the project. The main chassis of the computer fairly bristles with LEDs and chunky toggle switches for setting the data and address busses. The interior is no less tidy, with the 6502 microprocessor — date code from 1995 — and associated support chips neatly arranged on perf board. The construction method is wire wrapping, in keeping with the old-school look and feel. Even the hand-drawn schematic is a work of art — shades of [Forrest Mims].
As for programming, this machine is as low-level as it gets. Nothing but 6502 machine language here, entered manually with the toggle switches, or via an externally programmed ROM. The machine can only address 1k of memory, a limit which the code to support the RPN calculator add-on [Yamada] also built brushes up against, at 992 bytes. The calculator keypad has a 20-key matrix pad and an eight-digit dot-matrix LED display, and can do the four basic operations on fixed-point binary-coded decimal inputs. The brief video below shows the calculator in action.
We love the look of this build and we’re eager to see more like it. We’ve seen a ton of 6502 builds from discrete chips lately, and while we love those too, it’s nice to see one of the big old DIPs put back in action for a change.
Continue reading “Another Kind Of “Bare Metal”: 6502 Computer Powers RPN Calculator”
Still waiting on your Prusa Mini to arrive? Join the club. Between the incredible amount of interest in the inexpensive 3D printer and the COVID-19 pandemic, it can take months for the machine to arrive at your doorstep. But patient makers are finally taking delivery of their new printers, and as such the hacks and modifications are starting to trickle their way in.
First up is this gloriously over-engineered enclosure from [Build Comics]. While PLA and PETG usually print fine with nothing more exotic than a heated bed, trickier materials like ABS work best when the printer is enclosed as it helps maintain a consistent temperature. Plus it keeps any curious hands and paws a safe distance from the hot moving bits, and if things go really pear-shaped, can help contain smoke and flames.
The enclosure is made from welded steel square tube, wood, and fire-retardant fiber board. A hinged polycarbonate cover, taking the form of a four-sided cube, is lowered over the printer with some heavy-duty hinges that look like they were intended for a fence. To keep the cover from slamming back down, [Build Comics] came up with a simple locking mechanism that can easily be operated from the front or side of the enclosure. With the addition of a small temperature and humidity display, the conditions inside the chamber can easily be monitored.
But [Build Comics] didn’t stop there. He also rigged up a relay box that will cut power to the printer should the smoke detector mounted above it trip. While there’s no reason to think the Prusa Mini would suffer the same fate of earlier budget desktop 3D printers, but there’s certainly no harm in taking precautions.
Will you need to build a similar enclosure whenever your Prusa Mini shows up? Maybe not. But if you felt so inclined, at least now you’ve got plenty of images and details that can help you spin up your own solution.