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 of GPT is when things become so widespread that we see their applications all around us then they are General Purpose Technologies. In addition, my other criteria is when the economies of scale have brought their prices down to such an extent that these technologies become 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 230V(EU/AUS)/120V(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 charged 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. We all love light and color which LEDs are exceptionally good at producing.

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 even included the CR2032 batteries, 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.

The control of LEDs has also advanced and by mixing the intensity of red, green and blue, any color can be obtained from these three colour LED devices. Check out this rather inexpensive “Disco ball” which listens to the music and then responds with a fantastic display of color light.

Awesome “Disco Ball” using controlled LEDs

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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:

https://youtu.be/wUmTNQVoLPo

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.