Approximate Sine Waves (how approximate is that?!)

BX1300LCD

I just installed a UPS the other day (an older Back-UPS XS1300, pictured) and noticed on the back it’s an “approximate sine wave” output. After reading the bottom closer, it’s specified that the device, under 25% load, has a THD of 55% and a maximum harmonic amplitude of 43% of the fundamental’s amplitude. Sounds pretty bad, but what does that really look like? Continue reading

Using the STM32F4DISCOVERY on the Mac OS X 10.8.4 Command Line

6299osx-mountain-lion-iconThis will be effectively a copy of my previous post, but targeted at OS X. The gist is, get a toolchain, debug connector, and open-source firmware library set up to use the STM32F4DISCOVERY dev board from ST as quickly as possible on OS X. Unfortunately, it’s not QUITE as easy as on Ubuntu. Fortunately, it’s not a lot worse. Continue reading

Using the STM32F4DISCOVERY on the Ubuntu 13.04 Command Line

6299imgresThis tutorial follows the same basic outline as this post on cu.rious.org but some things have changed since that was written such that it no longer works unmodified, and the various similar tutorials leave some bits out. My goal here is to get some custom code on the STM32F4DISCOVERY board as quickly as possible, hopefully paving the way in the near future for a full eclipse-based IDE setup.

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Simple Button, Complex Design

I pulled apart my car’s start/stop button today to redo some chipping paint that was bothering me. Naturally, I couldn’t stop at only the cosmetic plastic once I saw that there was a small PCB inside. There are two interesting things about this picture. First, look at the PCB: there are some electronics (and more than just regulators to drive the LED), an LED to illuminate the button, and nothing else. Continue reading

BMW E90 DIY iPhone Mount (prototype)

I’ve been thinking for a while about how I want to go about mounting my iPhone in my car. For a while I had one of those suction cup mounts that gently clamps onto whatever phone or case you have, but it was pretty cruddy and snapped the other day. It got quite in the way as well. Looking around today, I came across Kuda which sells a bunch of custom-fit solutions that look very good though are quite expensive. I thought to myself that something similar wouldn’t be too hard to fabricate myself for a few bucks at home depot.

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More than you ever wanted to know about the MULF2 High Basis BMW Module

Being out in LA, I recently bought a car – I ended up with a used BMW. It’s pretty sweet, but I’m me so obviously I’ve moded just about everything I can without actually buying parts. Mostly that means software mods – windows up on key fob lock press, that sort of thing. But I’ve also been trying to mod bluetooth into it, and only recently had success. Tonight I got curious and took the module which controls bluetooth and USB aux-in apart (referred to as a MULF2 High Basis, it lives in the trunk and connects to a USB plug in the center console). Here’s what I found. Continue reading

How to organize your SMD parts, cheap (also, heat-sealing with a soldering iron)

I’ve amassed a lot of loose surface mount parts and it finally came time to do something about organizing them – digging through piles of little plastic bags in a box gets real old real fast. I considered buying something like Adafruit’s SMD parts kit and just stuffing my extra parts in the corresponding slots, but I don’t currently have a pressing need for all the parts, and I came up with something a little cheaper. Perhaps more interesting, I’ve got a nice recipe for heat sealing plastic (like anti-static bags) with your soldering iron without messing it up. Continue reading