I got a request from a YouTuber for the Libretto 50CT's software. Here it is, zipped up on the 50CT itself. 12MB of archives never felt so big 🙂» Read full post.
Quick one. For a project, I needed a really simple IR decoder program for an ATtiny85 that (a) Used interrupts for pulse processing, but (b) didn't use a timer interrupt, and (c) worked with an apple remote I had laying around. None of the libraries I found did this (mostly b, plus none really had the 85 in mind), so I whipped up my own. It's stupid. It's simple. It works well enough for me. Just whack your IR decoder's output to the 85's physical pin 3, hook a 9600,8,n,1 uart input to physical pin 2, press buttons on your remote, and marvel at the numbers and stuff appearing on your screen. Enough blab, here's the goods. This should work fine with pretty much any AVR, as long as you fix up the interrupt configuration in setup() for your particular chip.» Read full post.
So I made a little adapter so I can connect PS/2 mice to the pre-ADB Classic Macs (128k, 512k, 512ke, probably Lisa). They use a really simple scheme: two pairs of quadrature inputs (one for X, one for Y), and one input for the single button. 5v is provided for the mouse. Perfect for a little microcontroller like the ATtiny to interface to (which is funny, because the ATtiny is capable of a far faster clock speed than the Macs...).» Read full post.
Just a quickie, companion to my bedroom lighting project video here: http://youtu.be/QDfqHmQUCMA» Read full post.
So I picked up an old Mac 512k "fat mac" the other day. I was tearing it down for some maintenance, but encountered problems because a logic board was interfering with parts of the case. Turns out it was not a stock board - it was a 3d-party RAM expansion board: 512k Calmos 68k overview My teardown here:» Read full post.
So as it happens with these personal projects, I've finished the project but haven't finished updating the build log (yet). However I've uploaded a video to my YouTube channel that shows the final result. I'll post more as I get inspired 🙂» Read full post.
One thing I've found annoying with Arduinos is the relative lack of options when flashing sketches. A PC is pretty much required. Flashing in the field requires lugging around a laptop. I came up with a solution using the Zipit Z2 instant messenger client. It's a tiny device similar in form and size to one of those newer foldable GameBoy Advance handlelds. It's an interesting platform because of ability (Can run Debian Linux, has built-in WiFi), cost ($30), and battery life (around 5 hours). Unfortunately, it has no external serial port. Fortunately, it's easy to add. Just see this blog post by Geordy Rostad: Adding a Serial Port to the Zipit Z2. I did exactly what he did, except I omitted the level converter, connecting the serial lines directly to the new connector (such a converter would be superfluous when interfacing with an Arduino). Now, my Arduinos are generally at 5V, but the Zipit works with 3.3V. This isn't a problem with data going from the Z2 to the Arduino - 3.3V is plenty to drive the inputs of a 5V device. The other way around requires a voltage divider so we don't harm the Z2. Here's a quick schematic of my converter built into the cable:» Read full post.
Etched and populated the main amplifier board last night. Powered it on for the first time and... buzzzzzzzzz. Still sounded rather good with music in it. After a few hours of fussing around, I discovered it was my poor-quality temporary wiring input-side. Strange feedback loops and stuff. I'll be honest, analog circuits are still a dark art to me. Hopefully this project has helped dispel that 🙂 Anyways, now it's using shielded wire and... oh man. Let's just say this thing has broadened my musical horizons. I'll now listen to things on my playlist that I'd usually skip over - it's just such a pleasure to listen to this thing. Still some small noise when the music is stopped. I think that will go away once I finish up the wiring (still a bunch of unshielded sections). Even if it doesn't though, I'll be totally happy!» Read full post.
The SOHA's power supply is quite simple. It's quite clever how it obtains the ~40 volt B+ for the tube - it basically stacks two full-bridge rectifiers, decoupling them with big caps. To make case layout and circuit debugging easier, I decided to put the power supply on its own board and use various salvaged connectors to hook up to the main amp board. The only mod I made to the original SOHA circuit was use a bigger transformer (1000 mA) to power some eye candy (and put a bigger heatsink on VR3 to handle the extra power). Oh, I also removed the power LED (I've got other plans). I much prefer surface-mount assembly to through-hole (no drilling a thousand little frickin' holes), so I found equivalent SMT parts to the recommended through-hole parts. Here are the part numbers I used for the power supply (refer to figure 4 on the HeadWize page here). Note the connectors are absent from this list - I have no idea what I used. A few years back, some jerk broke our dorm TV. Silver lining: it contained lots of sweet surface mount connectors!» Read full post.
Parts! I love parts. I got a bunch of 'em in the mail for the headphone amp.» Read full post.