Hello world!

The first words you wrote when learning a new programming tool, be it Arduino C, Micro-Python, VB6, C#, Python 3 or coding frameworks for any micro-contollers.

This is the first thing anyone writes when they are learning a new programming language and it is very gratifying when you try something for the first time and are able to write these simple two words. I can do that on many LCDs connected to micro-contollers or connected to better and more modern OLED displays driven by either a: Raspberry Pi, ESP32 or many of the Arduino boards. Some of the projects described on this blog started out with these simple words and have advanced to more information over time.

In addition, I thinks its always great to greet your audience and so I say “Hello World” to you and hope you enjoy what I share in my personal blog. It somehow doesn’t seem right to me, to do something and yet not share it with those interested therein, across the world!!

General Purpose Technologies (GPT)

I think that we don’t always realise the impact that General Purpose Technologies (GPT) have had in our lives.

My definition is when things become so widespread that we see their applications all around us. In addition, when the economies of scale have brought their prices down to such an extent that it becomes ubiquitous.

The following picture describes four such GPTs, can you guess what that are?

Four GPTs that are ubiquitous..

So these are: solar panels, lithium batteries, passive infrared sensors and light emitting diode (LED) lights.

Their combined use, in this particular application, means that this could be installed by anybody as it is completely safe – a low voltage system. Thus no expensive electrician required to do the installation, no 230(EU/AUS)/110V(US) cabling and no certificate of compliance (CoC) from that same expensive electrician. The older halogen mains connected system would cost hundreds of dollars to buy all the components and get the licensed electrician to do the installation and then certify it as safe! The system shown here would cost less than $50 from a local hardware store and you could install it in less than 10 minutes without running foul of the electrical codes. The bonus of course is that it will still work during a power failure owing to the battery which is charge by the solar photo-voltaic panel so completely sustainable and renewable…

I love LEDs because their power consumption is very low and they are so safe, most of the individual units run on anything from 1.5V to 5V.

I was astonished how cheap these have become, these tealights would replace the dangerous open flame, candle-based units and last for many years. They also create a lovely ambience no matter what the occasion, even the occasional power failure (outage). These cost me less than 50 cents each within this 8 pack and I only need to get a bulk pack of the CR2032 batteries and viola! Date-night at home is going to be soo romantic due to this GPT :,-) Thanks to the engineer whom invented LEDs…

LED tealight “candle”set, all 8 for $3.90, a truly ubiquitous technology.

Thanks to Messrs Round (1907), Losev (1927), Biard (1961) and Holonyak (1962) and those that secured to increase their lumens output whilst driving their costs down. Thanks to engineers in companies like Toshiba etc we get amazing, commercially available LEDs, that have an efficiency of up to 223 lumens/watt.

Not all robots are equal

20 June 2020

You definitely pay for what you get with automation. I bought a 3-in-1 mop/vacuum/broom which was supposed to be all of that and have LIDAR and be able to self-dock and recharge. Well the fellas at https://keithlily.com are in the business of scamming people and caught me out. You will see the video on their site which advertises their product as having all these features and yet it has Velcro tags on the bottom to which very thin soft cloths are attached and these are then dragged across the floor. It came with about 30 of these replacement cloths. It does have a piezoelectric sensor in its “nose” that detects it bumping into something and then has a randomising algorithm which causes it to change direction, quite successfully. This algorithm and owing to its small dimensions, allows it to get-in under tables and chairs and cabinets and attracts “dust bunnies” to that cloth. A human would need to get down on all fours with a conventional vacuum machine and a fine nozzle to reach those places.

The concept is worth about $AUD 5-$10 and I would pay that for it, provided it didn’t get it self struck on anything that doesn’t activate the sensor so things less than, 5mm in height, or even getting caught out in grouting grooves on tiles when there is a lot of water on the bathroom floor. The fellows at keithlily (whom I later discovered our out of Azerbaijan, have a great marketing and delivery businesses model but just aren’t honest with their product). They will no doubt, not be a sustainable organization. They will constantly have to change their cover to keep duping people like me by over promising whilst also under delivering.

It did however get me thinking about what is now know as general purpose technology (GPT) and the specific version of this that is robotics. ABB have incredible robots that can do amazing things in a production line, even allowing for full customisation of each product manufactured. Boston Dynamics have created robots, with a level of realism, that defies what many thought possible just a few years ago. There are also amazing autonomous vehicles like the various Tesla models and the list goes on. On an affordability scale though, only the flight controller is at a scale of sophistication and cost that can be considered GPT, that is the flight controllers in drones. In pondering why that is, I realised that the more expensive automatic vacuum machines are only slightly better than my $USD 29.95 excluding shipping, light-touch, kiddies toy “robotic” broom. We had one from Roomba back in 2012 costing $AUD 350 and it kept getting itself stuck. I have no doubt that these have improved substantially since then, but still think that the performance versus price is still not compelling. This design needs a rethink. The flight controllers in drones are however GPT and have the right price versus performance proposition as I explain in the video below:

The link to the scammers site:


Technology in recycling

Automated glass recycling acceptance machine
Automated cartons, cans and plastic bottle acceptance machine

Machines have made the world a better place. It is actually the engineers who develop these machines that are responsible for such improvements. Take the machines that we have in Australia as an example, these eliminate the need to sort bottles from cans, from plastics etc. The device scans each device that is entered and either accepts it for the recycling credit or rejects it! This makes good sense for the company recycling these items and those whom can conveniently drive to one of these machines and quickly get some cash back. Here you could 10 cents per plastic bottle. This is sustainability as it should be.

The ubiquitous Raspberry Pi (RPI), as a Network Attached Storage (NAS) device

A Plex Server home screen. Running on a Raspberry Pi (RPI)
The Network Attached Storage (NAS) using a Raspberry Pi

I followed the instructions below here, in order to use the RPI as a NAS with a RAID-1 array with two mirroring 1TB Harddisk drives (the abbreviation for these is: HDDs, they can be seen in the photo). Samba is a service which makes the NAS accessible to Windows computers on the same sub net mask. The IP address and RPI credentials are used to access the NAS from a Windows computer. Also install CX File Explorer on your phone and then the NAS is accessible on you Android smartphone, a very cool feature.


I then simply used that same RPI which acts as the NAS, to also run the Plex server which is accessible behind the NAT by typing the IP address and port number which defaults to 32400. The Plex server is accessible with any webbrowser by any device on the same subnet as the Plex server. You can also set-up Plex server to port forward and thus serve you anywhere in the world using your login credentials. I have a double NAT, which means two routers between the RPI and the Internet Service Provider (ISP), so that is a tricky proposition to get external access for me. It can be done but one has to bridge the first router through to the second one, which I don’t want to do.

In the above photo you will see a powered hub and a RPI. The RPI gets its power from the battery bank and I will make a connection for the powered USB hub also to take its power therefrom so that it acts as a UPS, in the future.

Plex server instructions are summarised below:

Plex Install: https://pimylifeup.com/raspberry-pi-plex-server/

Set a Static IP for the RPI: https://thepihut.com/blogs/raspberry-pi-tutorials/how-to-give-your-raspberry-pi-a-static-ip-address-update

Install a Torrent Web App called Deluge: https://pimylifeup.com/raspberry-pi-deluge/

You also need to type in the following command:

sudo chmod -r 755 “your USB HARD DRIVE Path ie: /sda/pi”

This is required or the
Plex server won’t be able to read you usb drive.

If you don’t have a UPS and have a power failure and the RPI cannot see the RAID array follow these instructions:


Do I need to use vinegar when making biltong?

Hennie Coetzee’s biltong machine

This is a question which comes up quite often when people are making biltong.

The truth is it does give the biltong a ‘funny taste’ and in my experience is quite unnecessary, provided you follow two critical steps.

1) You need to leave the meat in the fridge in the biltong spices for about 48 hours so that a curing process takes place. The meat draws in the preserving salts and spices.

2) This step is very important as mould can form on the biltong if you haven’t used vinegar in the curing process. It is imperative that you monitor the humidity within the biltong Machine for the first 18 hours, this biltong machine should have enough heat generated within it, in order to keep the internal humidity levels at 100%. This represents a situation where the air is saturated with moisture that is being drawn out of the meat . This process rapidly seals the outside of the meat thereby preventing any mould etc. I use the DHT22 sensor to monitor the internal humidity, within the biltong Machine. The fan/s effectively vent this moist air out of the box, which is continuously being drawn out of the meat by the heat source.

I believe the vinegar was used prior to the invention of refrigeration, by the Voortrekkers in South Africa, in order to allow the curing of the meat to occur without any nasties coming into play. With the advent of a low temperature environment in the cooling compartment of the refrigerator, this acidifying process is no longer required for the curing. The heat source is thus a must to quickly seal the outside of the cured meat. I hope this will give you confidence to try out a new way of enjoying an old South African favorite – Biltong.

A friend of mine’s biltong machine. He uses an incandescent lamp (60 watts) as his heat source. The bulb was removed to show the fan. Credit: Hennie Coetzee

Dolphin robotic cleaner which needs a “robotic finger” to operate

2 February 2020

I started with a much simpler robotic finger, basically to save me the pain of opening my pool pump box, every single day and then pushing the cleaner button OFF and then ON again. You can however get as sophisticated as you want with this exciting technology…

I rent a house which has an absolutely brilliant robotic cleaner called a ‘Dolphin’. It works well except you have to switch it OFF, wait 20 seconds and then switch it ON again for it to operate.

Apparently the next model up has a bluetooth interface for many hundreds of dollars more. If I want that option, after the fact, I would have to replace the whole cleaner…not great news!!

I thus set-about making a “robotic finger” to mimic this action every day, at a set time.

I use the famous Raspberry Pi 3. The first version of the ‘Robotic finger’s was, ummm… unreliable mechanically, I thus redesigned it. It also has a camera which shows me that the pump is running and the LCD display of the Davis pH meter. The first version is shown below:

Output from pool cleaners' web interface on Jekyll
The RPI 3 takes a photo everyday of the Davis pH meter and the indication of the pump master controller and publishes this photo to a Jekyll website

The ‘Robotic finger’ work-bench tested as follows:

“Automation” is what robots do best, things that are either too complex or to mundane for humans. I love this simple robot which takes blood pressure, SPO2, pulse rate (PR) and temperature from your finger and displays these parameters on an OLED screen!

Pulse, blood-pressure, SPO2 and temperature, “robot”
It comes in different colours for those whom think the black unit is too bland!

Variations of the Beef Jerky Maker

2 February 2020

Biltong is usually not allowed to get as dry as Beef Jerky and uses different spices

There are many ways to make a food desiccator. My preferred way is to use my fan with heater mounted on it as, shown in this post:


I have also made one using two microwave oven fans and a microwave oven lamp, for the heat source. This one uses the Wemos Lolin32 with OLED display…which reports temperature, humidity and heat index as well as the low and high set-points of the temperature control band. The photos are as below:

Basket with shade cloth for drying fruit are laying meat down
Aluminium drip trays fitted to the bottom and a fan drawing in air from either end (venting out of the lid)
Wemos Lolin32 doing service in controlling the heat source between the two set-points (temperature and humidity from a DHT22 sensor)

The ‘Boake-Yak’, a solar-powered kayak

19 Feb 2017

I received a trolling motor which produced 45 lbs-ft of thrust and decided that it will make a great project to mount on to my wife’s kayak. This effectively creates an electric-kayak.

When I completed the project using a galvanised pole that mounts the trolling motor out to one side of the kayak, I made the following tongue-in-cheek video:


The last laugh was however on me as on its maiden voyage the trolling motor caused a moment and tipped me into the river. The battery was destroyed and I also lost some fishing gear. I then had to rethink this idea and came up with the idea of producing some outriggers to make the “Boake-yak” as my friends dubbed it, much more stable.

Electrical conduit connection for outriggers
The electric kayak, dubbed the “Boake-Yak” by my friends

Repairing appliances

My father was an appliance repair technician (before he retired in 1991) and it always fascinated me to see how he stripped, repaired and then reassembled microwave ovens, washing machines etc.

My inspiration to learn how to save money by fixing things myself – my beloved Dad!

I think it is also better for the environment to try and repair as much as possible. Manufacturers, however, don’t like giving out the circuit diagrams as they prefer to sell you a new appliance than for you to try and repair it, but here I show that: “there are ways and means to do it”.

By way of a bit of background, my wife bought a vacuum cleaner and after a few months, it no longer worked. I watched a few YouTube videos of how people disassembled them. I then was lucky enough to have a working unit on hand for comparison purposes. The appliance in question was the Dyson V6 portable vacuum cleaner.

Two battery vacuum cleaners, side-by-side for comparison

The comparison helps to visually see whether anything is broken and also to swap parts between the units. This allows one to follow a ‘process of elimination’ to find the defective part. In my case, I isolated the problem to the battery pack and more specifically, the charger board on the battery pack. I found that it doesn’t charge the batteries and two batteries had actually had their internal protective elements operate.

Testing each battery so see whether I get ~3.7V

I matched the two failed batteries, re-soldered the battery interconnections and then when that was done plugged the charger in. The red LED flashes for a few seconds and then goes off. This told me that the charger had an issue. I bought a new pack on-line fitted it and it is been working flawlessly ever since!

I will strip the battery pack for the good batteries and use them on other IoT projects.

A couple of lessons here:

1) If you can find a working comparison unit, it accelerates the fault-finding process.

2) YouTube is very useful for giving disassembly instructions and also describes some of the more common issues with that particular model. The ‘pulsating drive issue’ is commonly encountered when the filters are blocked on my unit, as an example.

3) If the red charger light flashes for a few seconds (visible from two plastic holes in the battery pack) and then no longer flashes, the problem is with the charger and battery management system (BMS), which is quite a challenge to repair. Search eBay for the size of the battery (in milli-amps) and this exercise will save you time and effort to replace it. I wouldn’t recommend opening it as it quite a challenge.

The battery charger and management system light (red LED) if this doesn’t stay lit during charging then it’s time for a new battery pack.