Net Work June 2024

This month the use of USB-type chargers is considered, including an explanation of Power Delivery (PD) rapid charging, GaN-based chargers and other features to look out for.

^ A typical high power USB charging lead showing A-type and USB-C type plugs

It’s now almost 30 years since the universal serial bus first appeared in home desktop computers. The ubiquitous ‘flat’ style USB A-type plug would eventually appear in all manner of consumer electronics, not just personal computers. The original boxy-shaped B-type plug was soon superseded by the USB Mini, Micro and finally the rounded-rectangle USB-C type connector that is in widespread use today.  A typical USB A-type to USB-C charger lead is shown (above). Currently, rechargeable devices mostly use a USB-C type port for charging up, though the older USB Micro jack still puts in an appearance.

Some USB chargers offer almost every power port ever made, and things get more complicated still when you learn that many USB-C ports can now act both as power inputs (for charging up powerbanks) and outputs (to power other devices) – the 20,000mAh power bank shown has a mystery USB-C on the side offering high-power bidirectional charging, but you’d never know without checking the user manual.

The latest USB 4 standard sees data transfer rates of up to 40 Gbps and, looking ahead, readers can expect to see all manner of confusion arising from the use of USB-C and USB 4 cables. As computer manufacturer Lenovo reminds us, they are not interchangeable, and you can read more on this at https://www.lenovo.com/gb/en/glossary/what-is-usb-4-vs-usb-c

^ The non-descript USB-C port on the side of this powerbank provides bidirectional rapid charging. You’d never know unless you RTFM!

Express power delivery

A basic ‘dumb’ 5V switched mode supply might be limited to, say, 2 amps or less, and charging up modern high-power devices can take an inordinately long time. USB chargers rated at 5V, 2-2.4 amps (P= IV, so 10-12W) also find their way into 13A mains wall outlets and power strips.  Basic 5V A-type ports even appear in bedside lights, offering overnight phone charging. I use silicone rubber port covers, available from AliExpress for next to nothing, to stop debris falling in or shorting out the USB outlet. One problem is, there’s nothing to stops kids from poking things like paper clips in them.

^ This mains wall socket from Seeswitches.co.uk has built-in USB A-type and USB-C charging ports.

^ USB charging ports even appear in some bedside lights. I use silicone rubber dust covers (AliExpress, Temu) to stop anything falling in.

To meet the need for faster charging times and higher power, Power Delivery (PD) standards offer fast charging through a USB-C port, as PD-compatible products can interact to raise the voltage and current, thereby reducing the charging time. With power levels exceeding 100W and reaching 240W, uprated USB cables with appropriate current ratings become necessary to get the most from the system. Some fast-charge leads have a built-in LED (below)

^ This neat USB charging lead is rated at 3.1A and has an LED charging indicator

^ A USB monitor on an A-type powerbank port showing ‘PD’ in action – delivering 9V from a ‘5V’ PD socket in this example.

^ This tiny USB-C inline monitor fits onto a USB-C lead so you can keep an eye on charging progress.

^ Shown in use charging a smartphone, with power (watts) and ‘PD’ displayed.

PD can be observed in action using digital monitors that are cheaply available online. A larger USB monitor is shown above that fits an A-type socket and displays the output on 7-segment displays.  I also show a tiny add-on USB-C inline monitor against a 50p piece for comparison, which shows wattage and a ‘PD’ icon when charging a phone and power delivery is operating.  These cost just a few pounds from Temu or AliExpress.

A detailed summary of USB PD protocols can be found on Wikipedia at https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery.  Quick Charge or ‘QC’ is an alternative fast-charging protocol used on some devices, and other proprietary systems are also available. With so many factors to think about, it’s easy to see the appeal of wireless charging instead of grappling with fragile cables, and these contactless charging pads are increasingly commonplace at home and in the car.

GaN is the answer

^ This Ugreen USB PD-compatible charger uses GaN semiconductors for compact size and greater efficiency.
This one has just a USB-C port, but the mains pins fold in for portability when travelling.

The latest crop of mains chargers now caters for fast charging and I was attracted to a compact ‘Nexode Mini 30W’ (maximum) type made by Ugreen. It has fold-away mains pins – a good idea when travelling – and the specification is typical of rapid chargers, switching intelligently between 5V, 9V, 15V and 20V and supporting PD3.0, QC3 and other protocols.

This compactness of this charger is down to the use of GaN (Gallium Nitride) power semiconductors rather than silicon. It’s claimed that GaN is as reliable as silicon, and as GaN is more efficient and can operate at higher temperatures, a greater power density means less heatsinking and cooling are needed, so a smaller but more powerful charger can be manufactured. When choosing a mains charger, a GaN type would make a good choice today and would likely be future-proof too.

GaN semiconductors are utilised in industrial power electronics, and more background can be found on the Texas Instruments website at https://www.ti.com/technologies/gallium-nitride.html.   The physics and merits of GaN power devices themselves are detailed in an academic paper GaN-based power device: physics, reliability and perspectives hosted on the HAL (Hyper Articles en Ligne) Open Science website at https://hal.science/hal-03421528/document.

Power crazed

The UK has spent £13 billion on a faltering smart meter programme to monitor electricity demand, with four million of them still not working properly, if at all. (A smart meter fault-finding checker is listed at https://smartmetercheck.citizensadvice.org.uk.)  Britain is also trying to swerve a looming energy crunch by building more gas-fired power stations, and proposals made by energy company RWE to build a new Combined Cycle Gas Turbine (CCGT) plant  – one that reclaims ‘waste’ heat to drive a steam turbine and generate more electricity – would include piping waste carbon dioxide into abandoned undersea gas caverns, in a race to achieve ‘net zero’. The plans wouldn’t be signed off by the Dept. for Energy Security and Net Zero (yes, there is such a thing) until the year 2027, RWE states, meaning that the new power station would be about half a decade away and new gas pipelines and transmission towers (pylons) would also be needed.

This stopgap measure wouldn’t be so bad except that, in the same locality, 1.5GW of modern gas-fired power stations were bulldozed in recent years simply because they couldn’t make any money. Appallingly, this included Killingholme “A”, a power station I adopted courtesy of National Power when the station was quite new, when researching my mini-series ‘From Pipelines to Pylons’ in the August and September 1999 issues of Everyday Practical Electronics. You can see the damage being inflicted at https://youtu.be/3k8SjEqVf0Q; a larger 0.9GW neighbouring CCGT station lies demolished behind.

Other news

Amazon US is discontinuing its cashier-less ‘Just Walk Out’ shopping technology used in Amazon Fresh stores in America (see Net Work, May 2021). A very good insight into the amazing technology is presented at https://www.aboutamazon.com/news/retail/how-does-amazon-just-walk-out-work.

^ Artist’s concept design of NASA’s Lunar Terrain Vehicle (Image: NASA)

NASA has short-listed three bidders tasked with designing the next generation lunar terrain vehicle. The rover would be used by astronauts as part of the Artemis programme and would enable them to explore the South Pole and perform scientific experiments further afield than they could on foot. In between manned missions, the rover could be driven autonomously, with the winning contractor being allowed to perform commercial tasks, controlling the unmanned rover remotely from Earth. A movie trailer is offered by NASA at https://youtu.be/zTHJ9zb8J2s

If you’ve ever needed data on legacy components such as old chips or transistors, or old computer software, one site worth keeping in mind is bitsavers.org, a resource containing 7.5 million pages of data maintained in an old-school file-area fashion for speed and ease of mirroring. One such mirror is hosted by the University of Kent, at http://www.mirrorservice.org/sites/www.bitsavers.org/ where archives of software, component data, test equipment and more will be found.  There is even an FTP server for good measure.

Indexes for legacy volumes of Everyday Electronics and Practical Electronics

Lastly this month, my thanks go long-time reader Chris Moore who wrote in to say:

“You may recall that, about 10 years ago, I produced an index for the first 15 years of “Everyday Electronics” (which was the longest unbroken run of the magazine that I had at the time). I have now completed this index and also produced an index for “Practical Electronics”. I have placed these in my Google drive at https://tinyurl.com/4ru6fbe6 .

Please take a look at these and, if you see fit, publish the details in your “Net Work” column in the next available issue of PE. Any comments you have on these items would be welcomed. Thank you, Chris Moore”

This is a remarkable piece of work and the result of diligent and painstaking work which I am sure will be a valuable resource for our long-term regular readers, congratulations Chris on your achievement and thank you for sharing them with us!

That’s all for this month’s Net Work – you’ll find more details in this month’s issue of Practical Electronics.