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On these pages you'll find mostly articles and how-tos related to Linux, programming, and electronics.
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How to create a free audio link over the Internet using an old PC, Ubuntu Linux and Icecast streaming software
Posted on June 8th, 2009 1 commentThe purpose of this article is to help you in creating a reliable and free one-way audio link over the Internet. The primary use case is to enable low-cost transmission of radio program from radio station premises to a remote broadcasting tower. The method explained here is suitable for other one-way transmission needs as well, but due to long latency it cannot be used for two-way conversations (use e.g. Skype instead). Streaming live audio signal from one computer to another can be accomplished even with old low-cost computer hardware and free open source software, which makes the setup very affordable and enables interesting use cases.Abstract
There are many different needs for sending an audible signal from one location to another. The technology that works in one use case may not work well in another. We can divide the applications into two main categories:
The applications in the first category are aimed for enabling conversations over long distances. Telephone calls and teleconferences are perfect examples. Within this category the sound quality is not the top priority, but low latency can be considered a must. Both closed and open source software solutions exist, the most well-known being Skype.
The applications in the second category are aimed for broadcasting an audio signal from a single source to a larger audience, which in general does not need to be able to communicate back to the source (i.e. the audience listens only). Within this category the sound quality is an important enabler for long listening periods, whereas long latency can be usually tolerated well. Both closed and open source software solutions exist, for example Shoutcast and Icecast.
The setup described in this article is intended to be a one-way pipe for high quality live audio signal. Therefore, these instructions are likely useful in use cases that fall to the second category.
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Interfacing old Commodore 64 printers with Arduino
Posted on June 2nd, 2009 4 comments
This article explains how to use an old Commodore 64 printer in Arduino projects. A simple schematic for an adapter between the printer and an Arduino is presented, as well as a software driver for easy printing from Arduino code. Arduino is a popular open-source electronics prototyping platform based on Atmel Atmega 168 microcontroller. Commodore 64 is a classic microcomputer from the 80’s that still has many fans. The printer that is here used with Arduino is Brother HR-5C thermal matrix printer, but other CBM-64 compatible printers should work as well.
Motivation
I still remember that long-awaited day when my dad brought home a Commodore 64 microcomputer! That device became to be my first computer, and I spent countless hours playing with it in my youth – mostly gaming, but also a little bit of programming with BASIC. I still have it, although it doesn’t work anymore… We used to have many peripheral devices, too: the famous 1541 floppy disk drive, 1530 tape player, joysticks, paddles, cartridges, and even a printer!
In fact, that printer (Brother HR-5C) was a wonderful little thing: battery or AC powered, printing on thermal paper and other paper types too with a ribbon cassette, supporting full CBM-64 character set and custom characters. The printer is still working just fine, and I happen to have a lot of thermal transfer paper in my storage (unused fax machine paper). However, since my CBM-64 is dead, I cannot actually use the printer
I’ve been thinking about building an adapter so that I could connect the printer to modern PCs. I just couldn’t find any proper reason why would I want to print with that device instead of my much better quality and faster laser printer…
Until, I got an idea…