All posts by scruss

Pleasantly futile: Dogecoin digging on the Raspberry Pi

I don’t recommend this in any way, but cpuminer will run on the Raspberry Pi. It’s pretty easy to build:

sudo apt-get install build-essential libcurl4-openssl-dev automake git
git clone
cd cpuminer/
./configure CFLAGS="-march=armv6 -mtune=arm1176jzf-s -mfloat-abi=hard -mfpu=vfp -ffast-math -ffast-math -O3"
sudo make install

I’m not convinced that the l33t funroll-l00pz CFLAGS are strictly necessary. Yes, you still only get 0.34 khash/s on a stock Raspberry Pi — which means it would take several days to earn 1Đ (or roughly 0.1¢).

I’m trying to find the most futile computer on which to dig Đ. My BeagleBone Black is (somewhat surprisingly) more than 2× as fast, once you replace the very limited Ångström distribution with Debian. I’m really disappointed that I can’t build cpuminer on my Intel Galileo. Its Yocto distribution is extremely small yet confusing. As the board runs burny hot under no load, I wonder how quickly it would glow white-hot under 100% CPU load.

Fixing a broken boombox

Catherine‘s Insignia CD Boombox with FM Radio Model: NS-BIPCD01 (CD-player/iPod dock thingy) just stopped working. The traces on the power connector broke when it got bumped. It was a bit of a bear to open up. I was going to submit this to iFixit, but their editor is horrid.

You will need:

  1. Phillips #0 screwdriver
  2. Phillips #1 screwdriver
  3. Nice thick guitar pick.

Insignia-NS-BIPCD01-opening1Underneath the device, peel off the two sticky feet next to the product label at (1). Underneath are #1 Phillips screws you should remove. These are countersunk, and should be kept separate from the other screws.

Insignia-NS-BIPCD01-opening2At (2), peel off the sticky covers and remove the #1 screws.

Open the CD door, and remove the #1 screws near the top at (3).

Remove the #0 screws in the handle at (4). We’ve accounted for all the screws holding the case together, but there are a couple of clips we’ll need to work on.

Starting from near the top of the handle, pry the two halves of the case apart with the guitar pick. There’s an insert in the handle which will fall out; keep it aside.

At (5) and at (6), there are clips inside the case which you’ll need to press on with the guitar pick to get them open. They’re quite fragile, and I broke two out of four. If you do break them, make sure the loose bits don’t rattle about the case.

The case should slip apart now, and there are several short cables connecting buttons, displays and power supplies. If you lay the box on its back (with the iPod dock uppermost) you can set the top of the case up on the main circuit board. This will allow you to get at the power/audio board, which is secured by two large-flange #0 screws.

2014-03-15-131248… and there’s the problem: the power trace (the lower of the three near the middle of the picture) has cracked. I re-soldered it, and also ran jumper wires between the pins. If this cracks again, the jumpers will be much more robust.


ICQuestionBank2csv: A tool to extract both the Basic and Advanced Amateur Radio Examination guides from Industry Canada’s rather annoying two-column PDFs. Written for IC’s 2014-02 database updates.

See: Amateur Radio Exam Generator.

Written by Stewart C. Russell (aka scruss) / VA3PID – 2014-03-07.


  • Perl, with Text::CSV_XS
  • xpdf tools
  • Bash
  • wget


Run either or to download the source PDF and extract the data.


WTFPL (srsly).

For all your HP 7470a plotter manual needs

On the off chance you need to control a 30 year old graphics plotter, have I got something for you:


The image links to a scanned copy of the HP 7470A Graphics Plotter: Interfacing and Programming Manual which I found on the web, and cleaned up. The pages have been OCR’d, so it should be searchable.