I have a few days off from work and it seemed like an ideal opportunity to tidy up my electronics bench. This would allow me to change out my old Gould 20MHz oscilloscope for something different.
In this case, the something different is a Hewlett Packard 54200A Digitizing Oscilloscope. I know it powers up, but as yet I don’t know if will serve as a reliable instrument for my experiments. Time will tell…
I have recently expanded my collection of the little Raspberry Pi computers as MyGoodLadyWife has bought me a Pi2. I am hoping to be able to use the extra processing power due to the increased clock speed and quad-core CPU to good effect as a controller for a software defined radio. (More on that to come…)
But first, I needed to install an operating system. I did not want to simply transfer the existing SD card from the Pi B+ that Hector was proudly sitting atop of in my previous post. This is because the Raspbian image on that card is crafted to work on an ARMv6 CPU, whereas I can now use an image for an ARMv7 ‘HardFloat’.
I wanted to stay with Debian on my Pi2 so a quick trip to the relevant page on the Debian Wiki shows that there is a suitable image available for Debian 8, otherwise known as ‘Jessie’. So, I opened up the SpartiPi case and swapped out the old B+ for the new Pi2 (note that the case takes the Pi2 with as much ease as the original B+ it was designed for.)
So, all set to introduce the Pi2 to Debian Jessie. What steps are needed to make it all happen?
First, follow the link from the Debain Wiki to ” Debian Jessie on Raspberry Pi 2 by Sjoerd Simons of Collabora”. This will take you to a page with more background information as well as a link to where the bootable images can be found. I ended up downloading the following files:
jessie-rpi2-20150202.img.bmap jessie-rpi2-20150202.img.gz
Great! I have the image file, but what does that bmap file do? On his page, Sjoerd recommends using a tool called ‘bmap-tools’ to write the image to the SD card. I had to pause to check if it was possible to install it on the machine I use to program my SD cards and yes, it is. There is a repository for OpenSUSE 13.1 which I currently use (as MGLW is very fond of Geeko the Chameleon, the OpenSUSE mascot!). I added a repository to Yast which I named ‘Tizen’ with the following URL:
http://download.tizen.org/tools/latest-release/openSUSE_13.1/
This allowed me to install bmap-tools after which I was able to bring up a root console, change to the directory where the image and bmap file were stored and use the following command to write the image to the SD card:
bmaptool copy jessie-rpi2-20150202.img.gz /dev/sdd
While at first glance it seems a lot of effort to install and use this tool it does have an advantage over using dd in that it gives an indication of progress in terms of percentage completed and it also gives an indication at the end that the process was successful.
The Pi2 is now on the bench, powered up and running Debian Jessie for ARMv7. I have been able to use the apt-get update and apt-get upgrade commands successfully so it looks like it is working correctly.
More to follow on my task of putting this little computer to work in my radio shack…
Just before last Christmas I took part in a kickstarter campaign to help fund the SmartiPi case, a Lego compatible case for the Raspberry Pi B+. This is what one looks like after it arrives in the post.
These are the parts contained in the package – The case, a Lego compatible top-plate, a camera case and a GoPro camera mount. (Oh… and some screws).
The Raspberry Pi slots in to the case without difficulty.
Four screws close the case, and it is ready for powering up!
Make sure you have plenty of extra Lego to hand!
The NRD-525 that was recently on the bench has gone back to the M6BOH/M6JOJ shack, but not before I had a chance to use it on my recently constructed random long-wire and 9:1 un-un. I had some fun getting the hang of decoding HF weather faxes using the FLDigi package which can be obtained from W1HKJ Software – home of FLDigi
The image looks slanted because I have not spent time calibrating the sound card on my laptop. I’ll come back to that another time…
My friend Brian M6BOH inherited a JRC NRD-525 receiver which at first glance seemed in good condition.
However, it soon became clear that all was not well. The set could be tuned with the large tuning knob, but several keys on the number pad would not work. Closer inspection revealed that the set had met up with a cup of coffee and the encounter had not ended well for the radio.
Once the radio was disassembled we could see the damage to the circuit board. With a bit of gentle persuasion some of the keys were returned to life with a stiff brush and some isopropyl alcohol, but others were beyond hope and needed replacing.
MyGoodLadyWife agreed to do the surgery for us on this occasion and after cleaning the coffee stained area thoroughly she then removed the dead switches.
MGLW then cleaned up the circuit board ready to receive new switches. The original JRC service manual lists a part number that allowed us to buy the exact replacement part from Farnell which was lucky indeed. They were cheap too, so we bought a good stock of them in case more are needed in the future.
Finally, the part MGLW likes best – soldering in new parts. Within a few minutes the new switches were fitted and we were re-assembling the radio ready for testing.
So… power on, tune up and… it works! I’ll do some experiments over the next few days and post up some of the results…
Several times a month I take part in the UKAC VHF contests on 6 and 2 meters. One of the problems I faced was that after a few minutes of calling CQ if the band was quiet, my voice was starting to get tired and croaky. I had thought about using a voice keyer, but it means extra kit to carry and provide power for when operating portable.
I recently heard about a modification you can make to the stock Yaesu microphone, by replacing the circuit board with a new one containing both a voice keyer as well as a speech compressor. This had to be checked out at once!
I ordered the “Sprach-Sendespeicher, Austauschplatine für Mikro MH31, Bausatz” (quite a mouthfull in any language) from www.box73.de. A word of advice here – Google Translate is your friend!
Now, be warned. This is a kit of parts to assemble, not the finished product. However, the surface mount part is already soldered to the PCB. All you have to do is add the conventional components and some link wires.
Fortunately for me, MyGoodLadyWife loves to do soldering, so she was more than happy to assemble the kit when it arrived. (Lucky me!)
Here’s how the finished item looks, ready for final fitting in to a new microphone housing I bought along with the kit.
My local bike shop recently spent some time pampering Rose, my touring bike and while there, she was treated to a new cassette and chain. What I didn’t realise was that the middle ring on the chainset also needed replacing. How did Rose tell me this? Every time I put power down through the pedals, the chain would skip and make horrible noises. Ouch! Poor Rose…
So, out with the debit card and a bit of searching found me a replacement chain ring and the tools to fit it. Rose is a happy bike once more!
The image shows the old and new 36 tooth chains ring side by side…
Welcome to Dark and Scary, a place for me to dump stuff from the furthest, cobweb covered corners of my brain to do with computers, electronics, cycling, dungeons and dragons and ooh… just stuff that keeps me awake at night thinking, and possibly, once in a while, it might actually be useful.