Learning new skills while self-isolating

Day 27 of 84

I’m nearly a third of the way through self-isolation, fifty-seven days to go, as advised by my cancer team but I don’t think I’ll be truly safe until a vaccine or a reliable test for antibodies is made available to the general population. Experts say that a vaccine for COVID-19 will not be ready for quite a while, at least a year, probably, so I may stay in Spain for even longer than planned. I’m not looking forward to when it gets really hot in Málaga as I don’t have an air-conditioner. I might need to buy one.

The prospect of business has fallen away completely but I am available online for anything IT related that I can do for you. You can contact me here.

In the meantime my attention span for reading books and watching movies and TV shows has shortened for some reason and I’m wasting a lot of time on Facebook, but otherwise I am progressing well with learning Spanish and I am revisiting my solar management project.

Spanish lessons

Spanish will be the first second language for me. Portuguese doesn’t count as I only know very basic stuff like asking for a table for x people, ordering food and drink, and basic greetings.

Sometimes it feels like I’m not progressing much, despite spending at least an hour a day on Duolingo, but it IS working. I chat with mi amigo, Manolo, daily on WhatsApp and we are increasingly communicating in Spanish, so I’m pretty chuffed.

I chose my profile to be public so if you join Duolingo you can follow me and see my progress. It was while investigating this that I found another website, separate from but approved by Duolingo, that tracks my progress in a more meaningful way and anyone can see it. Here it is:

My public Duolingo progress page
Ignore the profile picture. It’s not me. I’m using it to honour friends and acquaintances who believe in conspiracy theories

Solar management

As noted in an earlier post I have limited access to gas so I’m saving it all for cooking and not for running the fridge which is now running on electricity through EHU (Electric Hook Up).

This means that the solar management system I built is not suitably set up to maximise charging opportunities for devices. While the solar panel still provides useable power in the daytime the solar management system was still charging everything during the night. The electricity supply is keeping the leisure battery fully charged at all times and so the solar management system “thinks” it’s still daylight at night-time. I have to manually switch off the load output of the charge controller at night-time to reduce reliance on electricity. The load output is what the solar management system uses for power and measuring the battery voltage.

To get around this I decided to add a photoresistor in series with the existing resistor to the A0 input of the NodeMCU (hereafter “MCU”) and calibrate it accordingly. The photoresistor increases resistance as light fades. This is a shortcut method I dreamt up, a bit of a bodge, and subsequently wildly inaccurate, therefore not suitable for proper power management. The problem is that there is only one input (A0) for reading voltages. I am going to look at adapting the circuit to allow the photoresistor and the output from the battery to be read separately by the MCU. There are two ways I can do this:

  1. Possibly the simplest method will be to put a physical switch in the circuit to select one of two options: on-grid or off-grid. Each of these will select either the reading from the battery via a voltage divider (because the MCU will blow up if I don’t do that) or the photoresistor. The problem with this is that code has to be written so that the MCU can recognise if it’s reading the output from the photoresistor or the voltage divider. Thinking cap on.
  2. The other method is to add additional components to enable the MCU to switch between both inputs and then act accordingly (for example read the photoresistor first and if voltage is low send the MCU to sleep for an hour or two; if high, go on to read battery voltage etc.). This will be the most elegant solution as it won’t require me to operate a switch manually. I found instructions here to assist in the design.


There’s a lot of electronics involved in building the solar management system so while looking for courses online to learn more about this I remembered I started a course in electronics a couple of years ago on Khan Academy, so that’s good. I first heard about Khan Academy not long after it was launched in 2008 and thought it an excellent resource. I encourage you to check it out. This is the course I’m doing:

Electrical Engineering course at Khan Academy
The Electrical Engineering course at Khan Academy

COVID-19: Tackling the Novel Coronavirus

I completed the online course set up by the London School of Hygiene & Tropical Medicine, and very interesting it was too. I got a certificate! There are many other free courses, not just about COVID-19:

Free courses at London School of Hygiene & Tropical Medicine

That’s it for this post. Stay safe, and watch out for zombies!