Category Archives: Electronics

Cool Tools: Dino-Lite AM4113T USB Digital Microscope


The Dino-Lite Pro AM4113T 1.3MP Handheld Digital Microscope is a surprisingly handy tool for inspecting all sorts of fine details at home and on the road. The small size and light weight are ideal for travel. I keep this microscope along with several other tools in my “go box” of electronics supplies for overseas travel.

Dino-Lite offers a wide variety of digital microscopes with a similar basic design to the AM4113T but varying resolution and other features.  This particular model is not cheap ($399), but the extra resolution and features of the “Premier” series scopes are handy.  If you don’t need these features, there are several lower cost options available, including the lower resolution AM311S (which I have not used myself but gets generally positive reviews).

Here’s a sample image from the AM4113T (converted to jpg but otherwise unmodified):

A108 - 20150401_200212

The included Dino Capture software is surprisingly usable and allows you to take instant snapshots and videos and make a number of measurements and annotations directly within the tool (only supported on the more expensive Premier series).  This is super handy for field work.  For example, here’s a measurement of the angle of a USB connector relative to a PCB edge.



The USB 2.0 interface is fast and responsive which makes the critically important live preview (there is no viewfinder) a pleasure to use. There is a handy touch-activated sensor on the side of the scope for quick snapshots. (Pro-tip: mark which direction is “up” with a sharpie or you’ll get dizzy trying to orient the cylindrical scope every time you use it.)

Compared to more inexpensive USB microscopes, like the Andonstar OT-V1, the Dino-Lite offers significantly better image quality, one touch snapshots, a better focus mechanism, and better, more uniform illumination.

One disappointment is the very obvious rolling shutter, which is particularly annoying when the microscope is being used to make measurements without a stand. At this price point, I would have expected a sensor with a global shutter. Despite this limitation, the Dino-Lite AM4113T is still a very useful tool and has already helped me make some critical measurements in the field.

Cool Tools: Adafruit Edition

SMT/SMD Resistor and Capacitor Books

Adafruit Resistor Book
This 0805 SMD resistor and capacitor book is just like the ones sold on eBay and just as useful. 0603’s are here.

Blank books and pages are here.

65 Piece Ratchet Screwdriver and Tool Bit Set


This 65 piece ratcheting screwdriver set is a bit nicer than comparable offerings from Dealextreme and includes bits for many of the obscure screws you are likely to encounter when disassembling all sorts of electronic equipment and devices.

Bus Pirate

Bus Pirate

I’ve used the Bus Pirate to troubleshoot tricky I2C bus problems and to develop automated testing of complex touchscreen control electronics. This is a small fraction of its capabilities. This is a handy item to have in your electronics toolbox. Has Python support!

Modular Snap Boxes


These snap boxes are available in several sizes and colors (including an ESD safe variant) and are great for storing loose components and fasteners.

Cool Tools: Elecfreaks SMD Prototyping Shield

elecfreaks_smd_protoThese SMD prototyping shields from Elecfreaks are pretty useful for building and testing discrete circuits made with mostly 2 and 3-terminal surface mount devices. I’ve used them quite a bit over the past year to prototype power supply and switching circuits (mostly SOT-23s). I like to cut them into small pieces with a large metal shear and stick them to larger PCBs (the ones I’m testing/modifying) with thick double-stick foam tape.


Cool Tools: Metcal MX-5211 Soldering Station

Metcal MX-6211
This is it! This Metcal soldering station will make you put away your Weller or Hakko and never look back! The dual simultaneous iron feature means you no longer need to buy two Metcal base units in order to solder SMT components with both hands! At over $800, these cost more than most hobbyists can afford. But for electronics professionals, this is probably the best soldering iron money can buy today. Just think, a year ago I had to buy two stations like this to fully equip a single lab bench for two-handed soldering! seems to have the best price on these (free shipping for prime members!): Metcal MX-5211 Soldering and Rework System with 2 Hand-Pieces

Note: Tips are not included, but this iron uses the commonly available STTC tips that work with the older MX-500 series base units. Tips are not cheap, typically costing $15-$30 ea, but they will last for years of daily use if properly cared for.

I recommend the 700 series tips (STTC-1xx) for general leaded and lead-free soldering, although the tip life on the 600 series tips (STTC-0xx) is better and the lower temperature is fine for leaded solder and light duty use.

Here are some of my favorite STTC series tips:

  • STTC-125 – General purpose 1/32″ chisel, get this tip first!
  • STTC-117 – Beefy 5mm chisel tip. Like most of the fat chisels and conical tips, this will heat up heavy gauge wire scarily fast. Good for soldering heavy PSU or motor controller wires and ground planes. STTC-125P is also good for smaller stuff like SMD PSU caps and multi-pin connector grounds.
  • STTC-140 – Long reach angled fine point tip, great for general SMT work 0603 and below. I equipped my station with one of these and an STTC-125 and I rarely need to change tips.

Here’s a helpful selection guide that also shows just how many different tip styles are available.

If you just need one iron, the Metcal MX-5210 is cheaper and can be upgraded later.

Cool Tools: Flux!

I’m a believer in using the right flux for the job, and as such I keep a variety of electronics fluxes on my bench. Here are some of my favorites.

MG Chemicals 835


MG Chemicals 835 is an electronics-grade activated rosin (RA) flux that is useful for a wide variety of soldering applications. The high activity rosin formula is helpful for soldering corroded copper wires and oxidized components or tarnished copper clad. It’s readily available at most electronics stores, inexpensive, and versatile. The biggest downside of this flux is that since it contains a very high solids content (50%), it tends to leave gummy rosin residue on everything it touches (including your fingers). This flux is also available in a flux pen. The RA designation implies that all flux residue should be thoroughly removed after soldering to prevent long term corrosion and electrical leakage.

Kester 186

Kester 186 (datasheet) flux is a lower solids content RMA flux (36%) and IMHO the ideal compromise between activity and residue. If I had one flux on my bench, this would be it. Kester sells it in flux pens or by the gallon (and one gallon will last years in even the busiest prototyping lab) but fortunately you can buy smaller bottles on eBay. Kester claims the residue can be left on your PCB but I usually clean it off if long term reliability is a concern.

Kester 951

Kester 951 (datasheet)  is a low solids (2%)  rosin-free no-clean organic flux that is useful for situations where cleanup would be difficult or impractical and flux residue must be minimized. This flux is surprisingly readily available on eBay and seems to be very popular with the Xbox repair crowd. It is the lowest activity flux I have on hand and can be frustrating to use if the components to be soldered are anything but spotlessly clean. During soldering, this flux remains active for a matter of seconds before largely evaporating. I would avoid it unless you’re doing really fine work (eg. soldering close to bare die) where removing flux residue might damage bondwires or sensitive components.

 Flux Dispensers


These Plato flux dispensers are my favorite dispensing tool and are perfect for applying a precise drop of flux to just the right spot on a PCB, minimizing mess and cleanup. They are inexpensive, high quality, and easy to use. These are available from many distributors (Techni-Tool, Mouser, etc.), but I usually order from All-Spec because they typically have the best pricing. I prefer the Plato FD-21 (0.010″ needle) for thinner fluxes such as Kester 186 and the FD-2 (0.020″ needle) for thicker fluxes like MG Chemicals 835.