Day: February 5, 2020

Tipping Points In The Climate System: The Worst Kind Of Positive Feedback

February 5, 2020 by 266 Comments

With global temperatures continuing to break records in recent years, it’s important to cast an eye towards the future. While efforts to reduce emissions remain in a political quagmire, time is running out to arrest the slide into catastrophe.

Further compounding the issue are a variety of positive feedback loops that promise to further compound the problem. In these cases, initial warming has flow-on effects that then serve to further increase global temperatures. Avoiding these feedback mechanisms is crucial if the Earth is to remain comfortably livable out to the end of the century.

A Multitude of Causes

The issue of climate change often appears as a simple one, with the goal being to reduce greenhouse gas emissions in order to prevent negative consequences for human civilization. Despite this, the effects of climate change are often diffuse and intermingled. The various climate systems of the Earth interact in incredibly complex ways, and there are many mechanisms at play in these feedback effects that could tip things over the edge.

Continue reading “Tipping Points In The Climate System: The Worst Kind Of Positive Feedback” →

An EV Motor Controller Home Build

February 5, 2020 by 18 Comments

Many of us will have experimented with brushless motors, and some of us will have built our own controllers rather than using an off-the-shelf part. Doing so is a good way to understand their operation, and thus to design better brushless motor powered projects. Few of us will have gone as far as [etischer] though, and embarked upon building our own controller for a 300V 90kW traction motor.

The tricky part of a high power brushless motor controller lies not in the drive but in the high-power switching arrangements. He’s using a bank of IGBTs, and to drive them he’s using a smaller industrial variable frequency drive controller with its own output transistors removed. He takes us through some of the development of the system, including showing him blowing up a set of IGBTs through having too much inductance between transistors and reservoir capacitor, and then to his final design.

This is part of a project VW first converted ten years ago, and as part of a series of videos he’s produced one going through the whole project. It’s a fascinating breakdown of the parts required for an EV conversion, and the teething troubles he’s encountered along the way.

Continue reading “An EV Motor Controller Home Build” →

Serious Repair Work On The Amiga 600

February 5, 2020 by 4 Comments

The Amiga will be forever loved for bringing serious multimedia capabilities to the home computer market. However, these machines are now showing their age, and keeping them running can take a bit of work. [Drygol] isn’t one to shy away from the task, however, and set about repairing a few Amiga 600s that came his way.

First up on the docket is replacing the many electrolytic capacitors that tend to leak over the years. They can cause corrosion, destroying traces and other components, as well as failing themselves. [Drygol] is an old hand at this now, whipping out the hot air station and some copper shielding to protect delicate connectors from melting. A simple recap was enough to get one machine up and running, but the other was more recalcitrant. When swapping a dud CPU out, a pad was destroyed on the PCB. This necessitated some careful tracing, followed by a drill hole through the PCB to allow a bodge wire to run the signal from the other side of the board.

There’s also plenty of upgrades to be done; S-Video outputs instead of the crummy old RF modulator, and special interrupt switches that help when cracking games and doing assembly programming. Thanks to a rich aftermarket and vivid community, researching and performing mods is easy thanks to writeups and parts available online.

It’s a great example of the basic techniques one must master to keep old hardware on the boil. Learn to recap, refit, and hunt for problems, and you’ll be well on your way to maintaining your retro fleet for years to come. We’ve seen [Drygol]’s work before too – this vampiric A500 is a particular treat!