Software Scope using a Sound Card

I tried a simple software implementation of a digital oscilloscope using a PCI sound card and this software:

I connected its own signal generator (from the line out) into the line in and it worked — sort of. The input capacitors were skewing low frequencies. I de-soldered those caps but then hit a bigger problem of a floating DC component. Also, there was a lot of noise on the line.

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Etching the PCB: Copper etchant calculator

I really wanted to find out exactly how much etchant would I need for a given board. That would be at least a theoretical minimum to etch all exposed copper, so after some calculation, I made this table. In practice, you would probably want to double that amount to get it to etch faster, but that’s a good starting value to measure.

Ambient Weather WS-2080 hang fix

A weather station, Ambient Weather WS-2080 that I installed in my backyard has a receiver unit with a pretty nasty hardware issue: occasionally, its USB interface would hang hard. It could happen twice a week or once a month – it is very unpredictable and highly annoying. Once it happens, nothing short of a power reset of the receiver unit would fix it. You’d have to remove the battery or unplug the USB if you powered it through it. I’ve finally got around to fixing it. If you have a similar problem with that weather station, you may be interested to read on…

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Building a Custom Picture Frame

(This article was first written in March 2009 – now most of us have Android tables laying around performing this task and much more!)

For a long time, I wanted to buy an internet radio to get access to thousands of stations from all over the world. However, it seemed the market in the US was way behind that of Europe, where (especially in the UK) you could select among many models of digital, Ethernet-equipped radios. Many of them had features such as pausing and recording the audio stream.

Aren’t you also intrigued with these novel picture frames, but could never justify the price of one, with better models reaching hundreds of dollars and lesser models not really worth buying? Picture frames were one of the best-selling gifts in 2008, with an average price of $169 for a connected photo frame (EE Times, Feb 23rd, 2009), but people are mostly confused with the device. I’ve seen a few in people’s homes being used for several weeks and then collecting dust.

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VMSim – An Attempt at Virtualization

The x86 virtualization became a mainstream technology, but it was not always that way. Intel CPU architecture was not designed for virtualization, so it was relatively recent that clever software methods were devised to successfully implement it.

In this post, I want to share some interesting technologies I’ve discovered while writing a proprietary virtualization solution.

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