Soldering

Playing with electronics on the bread boards that come with the starter kits is fun. However it falls short of the excitement of actually building a circuit. I also had a reason in wanting to put together a more compact version of the fan control circuit. Soldering iron kits these seem surprisingly cheap, with set a that includes stands, spare bits, cases, snips and even digital multimeter all for less than £20. However checking out reviews made me realise that the 15W Antex iron I have had for the last 46 years is still well thought of. I have previously struggled to solder effectively with this iron but that was as much my technique as any lack in the tool.

Heating the iron as it was and trying to melt solder did not work. So, my first task was to clean up the iron. There were mixed messages about doing this, including suggestions to avoid any use of abrasive and that it was not worth trying. The best advice came from the Antex site FAQs. That advised:

The oxide can usually be removed from a COLD bit by GENTLE use of “Scotchbrite“.

https://www.antex.co.uk/technical/faqs/#23

In seems that Scotchbrite is a bane for those green plastic things that are used when washing-up. I used a Spongtex sponge with green plastic abrasive intended for cleaning non-stick pans. I then gently passed the flat side of the iron across the surface several times. This worked very well leaving dark marks on the sponge and cleaning the tip to reveal bright metal. The solder now melted readily.

In comparison to 46 years ago there are now many more YouTube videos to watch on soldering. This helped me pay proper attention to tinning the iron, i.e. melting solder on the iron before using it, and also appreciate that when soldering it is not essential to get it right first time as it is ok to reapply the iron to improve things. And so now ready to do some actual soldering!

Getting started with Raspberry Pi 4

For my birthday in November 2019 I was given a Raspberry Pi 4. I had mentioned that I thought one would be interesting when I retired and had then forgotten about the idea. I did not have any particular plans, but still fancied having one and so went ahead. There are several varieties of Raspberry Pi and went with the relatively safe option of ordering the most expensive variant in a starter kit. The kit that we ordered was the LABISTS Raspberry Pi 4 with 4Gb of ram, power supply, case with fan, micro HDMI cable and 32 Gb card with NOOBS pre-installed. The kit was £89.99, which is probably slightly more than buying all the parts separately. The most similar one currently listed is 2Gb version at https://www.amazon.co.uk/LABISTS-Raspberry-Starter-Motherboard-Preloaded/dp/B07Y8B321S/

The LABISTS Raspberry Pi starter kit

Installation was fairly straightforward. One issue was getting the display to appear on the TV. It seems that an adapter ordered at the same time to connect two HDMI connectors was faulty :-(. There are also two HDMI ports on the Pi and it looks like it matters which you choose. The picture then worked even if it was very small – as its scaled to the 4K TV. Perhaps best to install on an HD screen rather than UHD. After that though all went smoothly using NOOBS and installing Raspian.

This kit case came with a case and fan. Reading in various places the one downside of the Pi 4 is that it runs hot. Plugging in the fan meant connecting it to the 5v and GND on the GPIO socket with the result that it ran continuously. This therefore gave me my first project – to find a way to create a temperature sensitive fan …

WordPress installed!

Picture of the WordPress login
My very own wordpress login

I have now installed WordPress so that I can make a diary of the actions I am doing and remember what I have been upto!

Installing WordPress was fairly straightforward. As you would expect there are several post about how to do it. However there still remain a few catches. For example, mysql is no longer in the repositories for installation on Raspberry Pi and so the instructions at https://www.makeuseof.com/tag/host-wordpress-raspberry-pi/ could not be followed line for line. On the other hand the instructions at https://pimylifeup.com/raspberry-pi-mysql/ had been updated to use the correct database and so use mariadb in place of mysql, but missed out a minor step to restart the apache2 server after the installation of php-mysql.

Another thing that caught me out was the URL for the site. This started as localhost. This was fine for looking at it on the Raspberry Pi, however links and images did not work when viewed from other machines. I then put in the URL – 192.168.1.231. That seemed ok at first, however when I put the SD Card in another Raspberry Pi (the Pi Zero W running the Christmas Tree) the URL changed to 192.168.1.232 and again links were broken. I could not easily fix that as the login was also broken (there is advice about ways to deal with this at https://wordpress.org/support/article/changing-the-site-url/ ). It was simplest to reinsert the SD card into the Pi 4 and then login and adjust the settings again. So now set to have the URL http://rapsberrypi – not sure that is the end of the issue though! [This paragraph added 4 January 2020].

A bit more tweaking – I have now moved the WordPress installation to its own directory /var/www/html/wordpress. I followed the steps on https://wordpress.org/support/article/giving-wordpress-its-own-directory/ and also set the site URL to http://raspberrypi.home [6 January 2020]. New update [20 February 2020] now moved onto a static IP with our new provider Vodafone so have a public URL – www.mcandrewmk.co.uk and so needed to again change URL following instructions at https://wordpress.org/support/article/changing-the-site-url/ (though because of using a subdirectory had to set the WP_SITEURL to have /wordpress at the end.)

Anyway WordPress is now up and running! I will now try to remember to blog each time I do something interestingish. I also should do some retrospective bloggin about various things already done i.e.: