Silicon ChipPractically Speaking - February 2020 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Subscriptions: PE Subscription
  4. Publisher's Letter
  5. Feature: The Fox Report by Barry Fox
  6. Feature: Techno Talk by Mark Nelson
  7. Feature: Net Work by Alan Winstanley
  8. Project: Audio DSP by Design by Phil Prosser , Words by Nicholas Vinen
  9. Project: Motion-Triggered 12V Switch by Nicholas Vinen
  10. Project: USB Keyboard and Mouse Adaptor for Micros by Tim Blythman
  11. Project: Stamp-sized digital audio player by Jim Rowe
  12. Project: Colour Maximite Computer
  13. Feature: Circuit Surgery by Ian Bell
  14. Feature: Practically Speaking by Mike Hibbett
  15. Feature: Using Stepper Motors by Paul Cooper
  16. Feature: Max’s Cool Beans by Max the Magnificent
  17. Feature: AUDIO OUT by Jake Rothman
  18. Feature: Make it with Micromite by Phil Boyce
  19. Feature: Electronic Building Blocks by Julian Edgar
  20. PCB Order Form
  21. Advertising Index

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Articles in this series:
  • Techno Talk (February 2020)
  • Techno Talk (February 2020)
  • Techno Talk (March 2020)
  • Techno Talk (March 2020)
  • (April 2020)
  • (April 2020)
  • Techno Talk (May 2020)
  • Techno Talk (May 2020)
  • Techno Talk (June 2020)
  • Techno Talk (June 2020)
  • Techno Talk (July 2020)
  • Techno Talk (July 2020)
  • Techno Talk (August 2020)
  • Techno Talk (August 2020)
  • Techno Talk (September 2020)
  • Techno Talk (September 2020)
  • Techno Talk (October 2020)
  • Techno Talk (October 2020)
  • (November 2020)
  • (November 2020)
  • Techno Talk (December 2020)
  • Techno Talk (December 2020)
  • Techno Talk (January 2021)
  • Techno Talk (January 2021)
  • Techno Talk (February 2021)
  • Techno Talk (February 2021)
  • Techno Talk (March 2021)
  • Techno Talk (March 2021)
  • Techno Talk (April 2021)
  • Techno Talk (April 2021)
  • Techno Talk (May 2021)
  • Techno Talk (May 2021)
  • Techno Talk (June 2021)
  • Techno Talk (June 2021)
  • Techno Talk (July 2021)
  • Techno Talk (July 2021)
  • Techno Talk (August 2021)
  • Techno Talk (August 2021)
  • Techno Talk (September 2021)
  • Techno Talk (September 2021)
  • Techno Talk (October 2021)
  • Techno Talk (October 2021)
  • Techno Talk (November 2021)
  • Techno Talk (November 2021)
  • Techno Talk (December 2021)
  • Techno Talk (December 2021)
  • Communing with nature (January 2022)
  • Communing with nature (January 2022)
  • Should we be worried? (February 2022)
  • Should we be worried? (February 2022)
  • How resilient is your lifeline? (March 2022)
  • How resilient is your lifeline? (March 2022)
  • Go eco, get ethical! (April 2022)
  • Go eco, get ethical! (April 2022)
  • From nano to bio (May 2022)
  • From nano to bio (May 2022)
  • Positivity follows the gloom (June 2022)
  • Positivity follows the gloom (June 2022)
  • Mixed menu (July 2022)
  • Mixed menu (July 2022)
  • Time for a total rethink? (August 2022)
  • Time for a total rethink? (August 2022)
  • What’s in a name? (September 2022)
  • What’s in a name? (September 2022)
  • Forget leaves on the line! (October 2022)
  • Forget leaves on the line! (October 2022)
  • Giant Boost for Batteries (December 2022)
  • Giant Boost for Batteries (December 2022)
  • Raudive Voices Revisited (January 2023)
  • Raudive Voices Revisited (January 2023)
  • A thousand words (February 2023)
  • A thousand words (February 2023)
  • It’s handover time (March 2023)
  • It’s handover time (March 2023)
  • AI, Robots, Horticulture and Agriculture (April 2023)
  • AI, Robots, Horticulture and Agriculture (April 2023)
  • Prophecy can be perplexing (May 2023)
  • Prophecy can be perplexing (May 2023)
  • Technology comes in different shapes and sizes (June 2023)
  • Technology comes in different shapes and sizes (June 2023)
  • AI and robots – what could possibly go wrong? (July 2023)
  • AI and robots – what could possibly go wrong? (July 2023)
  • How long until we’re all out of work? (August 2023)
  • How long until we’re all out of work? (August 2023)
  • We both have truths, are mine the same as yours? (September 2023)
  • We both have truths, are mine the same as yours? (September 2023)
  • Holy Spheres, Batman! (October 2023)
  • Holy Spheres, Batman! (October 2023)
  • Where’s my pneumatic car? (November 2023)
  • Where’s my pneumatic car? (November 2023)
  • Good grief! (December 2023)
  • Good grief! (December 2023)
  • Cheeky chiplets (January 2024)
  • Cheeky chiplets (January 2024)
  • Cheeky chiplets (February 2024)
  • Cheeky chiplets (February 2024)
  • The Wibbly-Wobbly World of Quantum (March 2024)
  • The Wibbly-Wobbly World of Quantum (March 2024)
  • Techno Talk - Wait! What? Really? (April 2024)
  • Techno Talk - Wait! What? Really? (April 2024)
  • Techno Talk - One step closer to a dystopian abyss? (May 2024)
  • Techno Talk - One step closer to a dystopian abyss? (May 2024)
  • Techno Talk - Program that! (June 2024)
  • Techno Talk - Program that! (June 2024)
  • Techno Talk (July 2024)
  • Techno Talk (July 2024)
  • Techno Talk - That makes so much sense! (August 2024)
  • Techno Talk - That makes so much sense! (August 2024)
  • Techno Talk - I don’t want to be a Norbert... (September 2024)
  • Techno Talk - I don’t want to be a Norbert... (September 2024)
  • Techno Talk - Sticking the landing (October 2024)
  • Techno Talk - Sticking the landing (October 2024)
  • Techno Talk (November 2024)
  • Techno Talk (November 2024)
  • Techno Talk (December 2024)
  • Techno Talk (December 2024)
  • Techno Talk (January 2025)
  • Techno Talk (January 2025)
  • Techno Talk (February 2025)
  • Techno Talk (February 2025)
  • Techno Talk (March 2025)
  • Techno Talk (March 2025)
  • Techno Talk (April 2025)
  • Techno Talk (April 2025)
  • Techno Talk (May 2025)
  • Techno Talk (May 2025)
  • Techno Talk (June 2025)
  • Techno Talk (June 2025)
  • Techno Talk (July 2025)
  • Techno Talk (July 2025)
Practically Speaking Hands-on techniques for turning ideas into projects – by Mike Hibbett PCB digital microscope C omponents are getting smaller and none of us are getting younger, which means diminishing eyesight makes assembling electronic circuits increasingly difficult. In fact, even if you have youthful 20-20 vision, some SMD (surface-mount device) assembly has become almost impossible without aids. In the 1980s, a typical surface-mount device measured 2.0 × 1.25 mm. As a young engineer, these components were no problem to solder before the first cup of coffee, but 30 years later and after a lifetime of caffeine and day-long sessions in front of a computer screen, reading glasses are not enough. Glasses are great for reading books and restaurant menus, but the fine motor control and clarity of vision required to place solder and position an iron tip precisely on these tiny components becomes increasingly challenging. The solution is the inclusion of some form of desktop visual magnification. All professional PCB assembly houses use visual magnification tools in manual re-work and repair stations (mainly we suspect because the people employed in this work are more experienced, and therefore a little older!) We were lucky to obtain an old Nikon Stereo PCB inspection microscope many years ago, and it probably cost over a thousand pounds when new in the 1970s. Its construction quality is fabulous and will probably continue to serve the next generation. It’s a joy to work with and we have spent days at a time soldering boards while peering through it. These vintage microscopes are, however, very expensive when bought new, and good ones are hard to come by second hand. The author’s microscope (shown in Fig.1) is over 40-years old and ones of a similar age still sell for over £200. So what are the options for people keen to obtain some assistance? What to use? There is a wide range of options available on the market within a reasonable price bracket and, depending on your needs, a perfectly adequate solution can be found for home use. Generally performance is linked to cost, and performance in this case means: n Comfort in use n Optical quality n Magnification range n Image capture to PC n Physical build quality First, let’s talk about options to avoid. Lowcost ‘watchmaker’ glasses found on eBay are useless. They have a fixed magnification, and you have to have your face very close to the work surface, and hold your head still. Expect to burn your nose while soldering. Handheld lenses, popular and effective for reading books are cheap but require you to hold them – ‘losing’ one hand, and making soldering impossible. Budget optics A 10cm magnifying lens attached to a ‘helping hands’ stand like that in Fig.2 is a fair solution and prices start around £10, but of course they only give a single level of magnification. These are a reasonable starting point and we have one in our lab, mainly for soldering wires to connectors. They are of limited value for working with small surface-mount components, but at such a low cost are well worth adding to your collection of tools. At this price point it’s also worth adding a ×3 magnification ‘eye loupe’, as seen in Fig.2 next to the helping hands. Basic digital microscopes Cheap digital PCB microscopes – essentially a webcam on a stand – have become the modern solution to the problem. The image is displayed on a computer screen that you place in front of your work area, or on a small LCD display mounted on the stand itself. Avoid the latter – these small LCD displays cannot provide the clarity required. Again, performance is linked (Left) Fig.1. The author’s high-quality Nikon PCB microscope; and (right) Fig.2. Helping hands magnifier and loupe – useful but basic. 52 Practical Electronics | February | 2020 to cost. The cheap ones have short focal lengths, which makes putting the soldering iron under them difficult or impossible. There are other options available: large, desk-mounted lenses on angle-poise stands, some with integrated light sources, but again you are limited by a single magnification factor, and also there are no options for capturing images to a file. Despite the limitations, these will also be expensive, and not suited to kitchentable development. Instrument review For us, a primary requirement for the microscope was the ability to save the image to a file, specifically for publication within this magazine. With this in mind we set a budget of around £100 pounds (but not below £80) – we wanted to avoid the obviously cheap end of the market. It’s difficult picking the good solutions from the bad by looking at an advert on the Internet. Prices range from £50 or so to several hundred – but since we were ‘taking a risk’, we chose to go with one that looked right, at a reasonable price – £120 delivered in this case. We searched through Amazon, eBay and Banggood. Our choice came from Banggood (Item ID 1377420 at: http://bit.ly/pe-feb20-ps). We have made several purchases through Banggood before; the quality can be variable, but it is a stable and safe platform to make purchases on. As safe as any other Internet purchase, that is! The instrument is called, ‘HAYEAR 14 Million Pixels Full HD Color Screen Digital Magnifier Microscope 1 / 2.3 Inch Electron Digital Microscope Image Sensor With Bracket’. Let’s be clear, this is not an ‘electron microscope’, digital or otherwise! This may be a translation error – perhaps they meant ‘Electronic Digital Microscope’? It’s advertised as a 14-million-pixel device, but this is sly marketing – it’s a 2.1-megapixel camera; the saved image is simply scaled up in size by software. Sadly, no great surprise – that’s the standard of honesty we have become accustomed to when purchasing on the Internet. Delivery was a little quicker than the worst-case delivery stated, so pretty typical for Far-East shipments. The packaging was excellent, and it appears to be a nice solid unit with capabilities beyond those of a simple webcam on a stand. This was a good start. You can see the device in action in Fig.3 A variety of cables are included: USB to supply power to the two LED lights in the base; another USB for camera power and image upload to a PC; and an HDMI cable for direct connection to a display. As the device has a micro SD-Media card for image storage we set the device up for the latter configuration. A USB Practical Electronics | February | 2020 Fig.3. The digital microscope in use; the image is displayed on a large PC monitor. power supply was provided, but it was for a US power socket, so we discarded it and used our own mobile phone charger power brick. The addition of two light sources on flexible mounts is great; you can easily adjust both to find those hard-to-spot hidden dry joints. A variable resistor provides light intensity control, although with a poor range of setting – still, good enough. The 2.1 megapixel image quality is excellent, and the camera does a fine job of displaying components and solder joints. Good for PCB work A key advantage of this microscope is the gap between the workspace and the camera; it’s perfectly acceptable for soldering. It took about an hour to get comfortable looking at the computer screen (ie, away from the work surface), and for short periods of time it is excellent. If we have to spend hours soldering components, then the Nikon remains the preferred option – it’s more comfortable to use, very simple to set up (ie, no setup) and is of a build quality that means it will be in use for decades. The build quality of the Banggood device is mixed. The electronics, camera and lights are fine. The rack and pinion provided to raise and lower the camera, less so. They are metal parts, but of cheap quality and they frequently stick going up, which indicates this is not going to last for many years. That’s not a big concern; this device is ten-times cheaper than the Nikon microscope, and it offers many modern features. The system is modular, so you can move the camera and lighting to another platform at a later date if required. The final interesting inclusion is a remote control. The handset repeats the functions on the camera, with the main features being to take a photo to an SD media card, or adjust the zoom level. The zoom feature is useful, but it’s no magic bullet for adjusting image quality. For that, you need to adjust the camera height manually. From the highest point to the lowest, the basic optical zoom factor ranged from ×3 to ×10 magnification. That’s perfectly acceptable, and software-controlled zoom can triple that. In conclusion, was this worth buying? The answer is, it depends. If you need to move on from a set of ‘helping hands’, then you must decide if you need to take photographs of your board . If not, buy an old, second-hand PCB microscope for around £150. If a photograph and visual clarity for building projects is important, then this is a great purchase. It’s certainly a valuable addition to our lab, and you can expect all future Pic n’ Mix images of PCBs to come from it! 53