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.

Food Desiccator using Positive Thermal Coefficient heaters (revision 7)

28 December 2019

A delicacy called “Biltong” which makes use of different spices to “Jerky”

This is one of the best ways that one can start to make a difference to the planet, almost immediately!!! This is about focussing on living more sustainably. We have to eat, but we often buy much more than we can consume and throw away what begins to turn in our refrigerators. This is nothing short of wasteful, we are all guilty of this. More importantly, these desiccated food sources are actually all very delicious, think of: dried fruit, beef jerky, beef biltong and dried tomato on pizza. My favourites are biltong and dried banana…

The “heart” of the desiccator is the fan and associated PTC, “gentle”, self-regulating heater:

The side view which is the preferred position for resting on an old, upside down, plate saucer (preferably something ceramic) is shown below:

The bottom view (showing the fan unit) is shown below, this fan must face a 50cm diameter “air-port”:

Parts list

The items to get from your local hardware wholesaler, are as follows:

1) From Bunnings (AUS), Builder’s Warehouse (RSA), Home Depot (USA), etc. Get a good grade plastic container (relatively thick side-wall) that has a clip locking lid. This is important as the fan/heater creates positive pressure and needs to be sealed by these side clips. The dimensions are indicative and not crucial if you plastic container (box) is not exactly the same in size. Height – 0.5 m, Width – 0.5 m, Length – 1.02)

2) Get a “chocolate block electrical connector”, 230-240V, 10 Amp connector from the electrical aisle. These look like this:

“Chocolate block, electrical connector’

3) My “secret sauce” controller, ESP32 Controller, (optional) if you want Bluetooth control from your mobile phone and monitoring of the internal desiccator temperature and humidity. Send me an email request for such a unit from the contact page on This is not essential and only a ‘nice to have’. It will set you back about $USD 55 excluding shipping.

4) An old computer cord, preferably where somebody has stripped the insulation off the computer socket end, or ask the people at the Hardware store to make it look as in the picture below:

Note different countries have different plugs and colour codes for live/active, neutral and the ground or earth conductor

5) Shade cloth about 1-meter square will do, aluminium fly-screen is even better if you can get it:

6) A glue-gun to glue the shade cloth over the “air ports”. It is also possible to use duct tape to hold the screens over the “air-ports”.

7) Dowel rods cut to 550mm lengths by the hardware store, but at least 50mm longer than the width of the plastic box. eBay offers sets of 21mm diameter, dowel rods.

8) Four self-tapping screws to attach the fan/heater over one of the ports. 14g or 1.6mm will do.

Conversion between different self-taper screws in different countries

9) A 1mm drill to drill the “air ports” and pilot holes for the self-taper screws.

10) A pack of hangers, actually paper-clips where you twist the ends to make an accentuated s-shape


1) Drill about 150 holes from the inside out in about a 50 cm diameter grouping. Do this in four places with one such an “air port” in the lid of the plastic box
2) Ensure that one “air-port” is covered by the fan of the heater/fan. The best way to do this is to take a piece of paper and mark the flange holes thereon using a pen. Place the unit onto an old plate and using a screwdriver mark the top left hole of the flange against the box.
3) Use the template in 2), mark the pilot holes for the heater/fan.
4) Make an “air-port” around these four holes but mark the key four anchoring holes with a marker
5) Cut the shade cloth large enough to cover the “air-ports”.
6) Using the glue-gun cover the “air-ports” with shade cloth by gluing the shade cloth to cover the 50 holes produced in 1)
7) Attach the heater/fan using the self-taper screws

8) Make a 22mm hole to pass the red/black and green cables from the heater unit to outside the box

9) Seal up the hole with the glue gun

10) Connect red to red or brown, yellow to black or blue and green/yellow to green/yellow earth using the “chocolate connector block”

11) Have an electrically qualified person check the connector and then wrap it in electrical insulation tape

12) Measure from the top of the plastic box a line about 10cm from the rim on both sides, mark it with a line. At 50cm spacings from the side one side of the plastic box, mark an X. Drill 22mm holes on these Xs for both sides of the plastic box.

13) Push the dowels into these holes until the protrusion are the same on both sides then glue the insides of the penetrations with the glue gun, this holds them in place.

14) The dowels will allow you to attach meat and fruit etc. to the dowels hanging in the box

15) Avoid hanging anything over the heater/fan, this will foul it over time making it less effective.

16) Google “Crown Biltong spice” and buy a packet of this spice, follow the instructions thereon for venison, lamb and beef. Hang the meat on the dowels using paperclips.

17) For fruit make a 20% mixture of lemon juice and water and dip these fruit slices therein before hanging up with paperclips.

18) Hang meat or fruit and check daily by hand squeezing the food until it feels hard with a semi-soft centre or when the “secret sauce” controllers report 40% humidity in the box, it will be sealed.

19) After 3-5 days depending on local climate, enjoy your sustainable, desiccated food!!

If you can find a basket that fits into the box it is much easier than dowels

A version with two fans and heaters can be seen in the following link:

Store in a brown paper packet and if you allow the centre to remain soft you can cut it with a serrated knife.

It is good to protect the whole setup with voltage and current appropriate fuses. In my case the LittleFuse Inc units are rated for 230V and I use a 3 amp fuse:

230V 5Amp Little Fuse Inc.

I posted a YouTube video to talk you through the build here:

Build video here

Alternatively, The ‘secret sauce’ controller is a controller that can switch the heat source every few seconds, giving better control in making your dried foods. It also allows all interactions via Bluetooth from your mobile phone and if you connect to your local Wifi will show progress on a webpage, how cool is that! It also uses RF to control a plug socket so no electrical connections required. This is the state-of-the-art. If you want to buy a plug and controller it costs $100. Leave a comment we will get your details for an order. You are really going to love it! 👍🌟🥩🌟👍

Power Bill Shock!

29 October 2019 (first created)

I am sure many of you have opened your monthly electricity bill only to feel a little bit of panic rising as your mind tries to comprehend the number before you. In my case it was the eye-watering $601.3, which was laid before me.

If you are anything like me, your mind raced to figure out what happened, right!?…Did we perhaps leave something on for a while, like a heater, the oven or a few split-system air conditioners? The heating appliances are typically the biggest energy consumers and air conditioners (in aggregate, if you have more than one split-system) can also result in some hefty numbers, especially if these are used days on end.

On my September bill the energy consumption was nearly double what it was as compared to the two coldest months in our city which are June and July. The green box, that I have marked up on my bill, shows those two presumably high consumption months and the red box shows the actual high consumption months.

These values in my bill are daily averages and gave me the insight that we ran a daily average consumption of a whopping 85.04kWh for September, …ouch!!. If you take the average daily cost and divide it by the average daily consumption, the numbers in the purple box, you may observe what the energy company charges me, per kWh of electrical energy. In this case this calculates to a rate of about 25.3c per unit for September. Not cheap by any stretch of the imagination and one of the main reasons that Australia has some of the highest roof-top PV penetration levels worldwide.

As I rent the house I live in, solar Rooftop PV isn’t an option for me. The house has solar pool heating whereby water is pumped to black heat receivers on the roof of the house.

The greater sense of dread comes from a feeling of: “Is this is our new bill going forward”? The first thing to do is check the meter reading (on my energy meter I have to read each digit from its corresponding dial for the various unit denominations: 10,000s, 1000s, 100s, 10 and 1 units, see the meter dials on the meter in the photograph below) and then confirm that the energy retailer has the correct numbers.

Then check the rate and see that this hasn’t changed from the previous months by recalculating the purple number from the previous month’s bills. This way you know that the rate hasn’t changed which may be responsible for this bill shock.

I my case, by analysing the bill I discovered that the problem was actually due to the readings being higher than the estimate that the energy company used. They seem to take the average over the last three months if they don’t have a meter reading.

When our consumption rose in winter, the 4 month accumulated correction of an additional 50kWh per month was not included in their estimate and when my wife phoned through the actual September meter reading, they made the correction. This added 200kWh to that month’s bill.

At least I knew that the bill wasn’t going to remain double but that it would still be higher than I anticipated. The important thing was to also phone through the next bill or else that would affect the retailers’ estimate and they would be holding my hard-earned coin.

This event did get me thinking that I need to have a bit more control of what is going on with my energy (electrical) bill.

I decided that I need to keep an eye on the pattern (or ‘load profile’ as it is more formally known as) in order to understand how, when, what is using power in my home.

This makes economic sense but as power generation from coal generates, just under 1kg of CO2, it is also good for the environment for me to do this.

You can use these handy little plug-in meters (as below) and make up and inventory of the average of each appliance. This helps you to keep stock of the usage.

I however decided that I want more information and a trend line which I can view anywhere and possibly also analyse using tools like those available from Thingspeak/Mathworks:

I also wanted to separate my house from my pool pump as I am able to set that timer and maybe optimise the energy that the pump uses within the context of the water quality. I thus searched for an energy meter that I could build and found a few. (See my blog post on how I monitor water quality:

I opted for one based on a Atmel/MicroChip ATM90E32S chip on a printed circuit board (PCB) from a company called and which could communicate using the ubiquitous Wifi chip, the Espressif ESP32.

I also wanted two clamp-on current transformers (CT), one for the house supply and one for the pool supply, which this board allowed for.

The meter would need to derive its voltage reference and power from a plug-back power supply transforming the 230V supply down to 9V ac.

The clamp-on CTs simply clamp around the conductors on the back of the distribution board.

(Note: It is advised to get an electrician to connect these and put a plug socket into the board for you. I was lucky as my board already had a plug socket for electric lawnmowers).

The component elements that I used are shown below, and I put them all in a nice water-proof enclosure with leads for the plug-back and the CTS external to the enclosure.

The Wifi radio cannot transmit its signal through the steel box so I had to mount this box below the distribution board, out of the sun.

As you will read further on in this post, I found the signal strength with this external mounting of the power meter, inadequate for the reliable Wifi data transfers to the cloud service.

I also got a free cloud account from and set up the Wifi chip to send data to the cloud so that I can look at the load-profiles.

Notice the two times that the kettle was put on to make coffee. By taking a few minutes in the morning and evening to look at these load profiles I can see the overall power trend and can compare this to how the pool filter pump affects the overall numbers (which is currently my single largest power consumer, since it is early summer and there is no need for indoor space heating or space cooling).

If I turn an air-conditioner on I can see the step increase in power in the next 5 minute average value and then know the impact of when I turn things on and off. I now have a very clear picture of what is happening at my house and hopefully should avoid any further bill shocks.

If you want one of these units let me know by dropping me an email at the email on the Contacts page.

Now I can watch my consumption and turns things ON or OFF to see their impact on the profile.

Key lessons learnt

  1. HTTP posts to the Thingspeak IoT platform are not as reliable as using the MQTT protocol to send data from the energy meter. The latter also uses less power.
  2. The use of a microprocessor combined Wifi device should make use of an external antenna which should be mounted through the power distribution box using a rubber grommet. This improves the signal quality of the communication between the home router and the energy meter. The device reports an RSSI of between -50 and -55dB which may be considered as a “good” signal.
  3. I have been able to reduce my energy bill by $100 a month by learning what the filtration and solar heating (water pumped to the roof of the house) requirements of my pool are without over filtering or heating the water!
External antenna improves the reliability of the connection with the home router
“Good” signal strength with the homes’ Wifi router

It’s is always good to see what is out in the market. I came across this system from Smappee which looks good but will cost about double what my CircuitSetup system costs. It does have one great feature which is the ability to discern the different home appliances from one measurement.

Water Quality, for pools and ponds

29 October 2019

We bought 9 Comet (a type of goldfish) and put them in a water plant filled oasis, at least that is what we thought until 6 of them didn’t survive three weeks.

To make matters worse the three remaining fish developed a disease called Ich.

A bit of research and I knew that I need to not only have plants to remove nasties from the water but that I also need to keep the dissolved oxygen high (using a pump and a bit of a waterfall), pH within a tight band and watch the temperature of the water to prevent these events from recurring again.

I built a lovely little Wifi-enabled pH and Temperature sensor and was sending the data to a website.

I then decided that it needs a battery pack and so modified it to accept such a pack and charging from a standard USB lead. I now also use it to check my pool water. I also added oxidation and reduction potential, also called “ORP” as a bit of research tells me this is a good indication of water quality!

The ESP32 integrated micro-processor and Wifi are inside an old underwater camera case. The three key values are shown on the display.
A BNC-type connector serves to connect both the blue pH and the black ORP sensors which are stored in their buffer solution caps strapped to the box (the internal battery is charged using the USB socket shown)

I am a huge fan of Thingspeak and the MQTT API for sending data to their cloud IoT ecosystem. For those so inclined, it allows for some rich data analysis and visualisations as Mathworks are the holding company thereof. Mathworks of MATLAB simulation fame. I don’t use their coding framework, as it is proprietary and prefer Python for coding data science scripts. Open source is better in my opinion as the help from community members is far greater than closed communities like those who can afford to buy and then use MATLAB.

Energy Management, but how?

First published: 11 June 2018 then updated 27 June 2020

    Most countries have energy labeling, but so what!?

    It took me a bill shock event to get me to really think about what to do. Of course managing your energy is good for the pocket but it is also good for the environment. You might ask how can anybody with a Ph.D, in this very field, get caught out like this? The answers is simply based on a few considerations:

    🚦When you do something for a living you don’t necessarily want to have much to do with that field in your spare time, not so?

    🚦When the bills are all within  tens-of-dollars of each other, each month, you tend to “take your eyes off of the ball”, as it were 🤓. I guess I have so many things competing for my energy and attention that I generally do not fix anything until it’s broke. Unfortunately, not monitoring you energy bill already qualifies as “being broke” 🤓

    🚦The “bill-shock” is something that you get days or weeks after something within your house changes, this with respect to you energy consumption. It is what I call an “after the fact” event, this the criticality of having a phone app that warns you when your bill goes over some preset threshold in kWh/day. I now have this but it took this energy cost-spike to start “practising what I preach” 🤓

    I have a Ph.D in strategic management around energy management, so have sacrificed significant free time in the study, research and development of strategic frameworks to help all people save money, become more sustainable by saving on utilities bills.

    Watch my video to see one methodology that may be used:

    PowerWin entering energy uses into a spreadsheet used by the model
    PowerWin Logo

    The Bill shock! post describes how you can monitor your bill and calculate your daily energy consumption in kWh.

    At a very fundamental level just knowing that each kWh costs a certain number of cents and being aware of how many cents you are using per day, is a very good start. In Australia, in Victoria, smart meters have been mandated for a while so to get that daily energy consumption from your retailer is really easy. In NSW, where I live, it is only mandated for new builds.

    As explained in my Bill Shock! post, I rent the property that I live at so I couldn’t make a permanent installation. I did get owner permission to make a little hole in the distribution panel for the antenna of my smart meter, so that it could reach my Wifi router.

    I monitor the following trend line, especially when running my solar heating and filtration system for the pool (wattsC(W)) or the reverse cycle air-conditioning for heating in winter. The total house load profile including the pool system is labelled wattsA(W), this on the y-axis of that chart. This keeps me, well enough, informed as to my costs on a real-time basis. In my case every kWh represents a 25c ‘assualt’ on my wallet.

    “Some have studied their fields over countless years, thus you can trust them more than those trying to make a quick sale…”

    Hootie the animatronic owl

    3 June 2018 and updated 27 June 2020

    Conceived as a scarecrow, albeit in owl and not human form, Hootie changes randomly between pre-recorded, real owl calls, flapping its wing tips and turning its head which holds a 10mW laser beam. Birds hate the laser beam. Watch the video, which shows birds (actually flying rats) offered yummy food and yet even the most brazen of them scatters when the head turns and they are exposed to his imposing laser beam. Its main use is to keep other birds from defecating on garden furniture (what my wife originally wanted it for) around homes or more significantly, preventing them from pooping on PV solar panels thereby shading them from the sun and reducing the energy that they produce. I keep seeing other applications like keeping seagulls off of boats.

    Boat owners could benefit from owning a Hootie to keep seagulls off of their canvas biminis.

    I had a glitch with Hootie because I didn’t keep up with technology in power converters. I used the 7805 voltage regulator and yet the cost of buck converters have dropped in price, a far superior way to derive the 5V from the 12V is to use the LM2596S buck converter. The 7805 degraded over time until it was struggling to produce the required current to charge the battery of the powered speaker and supply the Bluno controller with Bluetooth. I rewired the system and tested Hootie from the phone APP as follows:

    Rewiring with bigger wires
    The APP used to test the code running on Hootie via bluetooth
    The updated LM2569S

    The technology from these folks was developed long after my first incarnation of Hootie, perhaps that got their idea from me. I like to think so 😁

    Good on them for commercializing what I discovered by trail-and-error:

    AVIX Autonomic the automated laser bird repellent