Electronics

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Electronics Bench
Electronics Bench

Our electronics area contains various test equipment, tools and supplies to help repair and build various electrical/electronic items. We have a four channel digital oscilloscope, a dual 30V 2A bench PSU, two Fluke digital multimeters + various cheap ones, two temperature controlled soldering stations, and desoldering/rework stations as well. See our Facilities page for a more comprehensive list.

Analog Electronics

We have a number of S66D six transistor AM (medium wave) radio kits available that are a good introduction to through-hole kit construction. They aren't great radios but when carefully constructed and properly aligned, typically work as well as most comparable '70s commercial Transistor Radio designs. Unfortunately the kit instruction leaflet is in Chinese but we do have the English instructions to refer to during construction. Also, here's an English language blog post of an Australian biomedical engineer & maker, building the same kit.

Micro controllers

Collectively, we have experience with:

We have a few microcontroller development boards available for self-education, project prototyping and other temporary use, including a mostly complete Funduino kit (ATmega328P Arduino Uno clone) with various sensors.

General

and experience with:

  • PCB design
  • DIY PCB making
    • Toner transfer method
    • Etching
    • Tinning
    • Solder mask (UV Exposure)
    • SMD stencil etching
however it is hard to justify making PCBs 'in house' due to the low cost, quick turnaround, and superior quality of the various far East PCB prototyping services. We do not have PCB making equipment at RML.
  • Soldering techniques

Tutorials and links

Soldering

Over forty years ago PACE released a series of training films to the electronics industry. More recently PACE re-released them on Youtube.

  • PACE Rework and Repair (Lessons 1-8) - You've found the fault, but the PCB itself is damaged or you are unsure how to tackle replacing a component. Watch this series and learn how far the professionals can go to save a high-value board!

Youtuber Dave Jones (EEVblog) has done several soldering tutorial videos.

  • EEVblog #181 - Dead Bug Prototype Soldering - How to solder a small 3 axis accelerometer LGA surface mount chip “dead bug” style onto a microcontroller prototyping board
  • EEVblog #346 - MLF/QFN SMD Reflow Soldering - How to use solder paste and a hot air gun to reflow solder a surface mount SMD 0.5mm pitch 3mm x 3mm MLF (QFN) chip
  • EEVblog #434 - SMD Thermal Pad & Drag Soldering Tutorial - Another method for hand soldering a surface mount SMD chip with a thermal pad, using both liquid and gel flux. Also drag soldering a TSSOP
  • EEVblog #688 - How To Rework Solder SMD Chips - Replacing a blown SSOP surface mount chip with ChipQuik, solder wick, and drag soldering
  • EEVblog #782 – The Dangers Of Reflow Soldering - Reflow soldering in a DIY oven can be tricky business for connectors and other parts, particularly ones designed only for through-hole soldering.
  • EEVblog #1064 - Soldering Irons OLD vs NEW - What are the differences between the “old” style soldering iron tips like used on the low cost Hakko and Weller et.al low cost irons, and the more expensive integrated tip type?
    • EEVblog #1065 – Soldering Iron Power Delivery Explained - Follow-up to previous video, + the differences between applied power, tip design, sensor design, control loop design, and power delivery to a ground plane.
  • EEVblog #1113 - Is a $5 USB Soldering Iron Useful?


  • NASA Workmanship Standards - A 'must read' if that soldered (or crimped) joint is mission or safety critical. Most of us will never need to apply them in full, but its good to know what 'best practice' is

Building Prototype Circuits

Test Equipment

Oscilloscope

Wire

Beware of counterfeit wire!

Fake copper wire has become an increasing problem in recent years. Here's what BASEC have to say about the issue: https://www.basec.org.uk/resources/counterfeit-cable/

As makers and electronics technicians, we are most likely to encounter fake copper wire in smaller gauges. The three most common types of fake copper wire we are likely to encounter are:

  • Insulated wire and cable with significantly smaller copper conductor CSA (cross section area) than the minimum required for that wire gauge, which results in a higher resistance, with the possibility of overheating and even fire if you pass high currents through it. You'll spot this as soon as you strip the end of the wire, but it can catch you out if re-using mains leads with moulded on UK plug to C13 ends.
  • CCS (copper clad steel) wire. Its far stiffer than copper wire of the same CSA, has much higher resistance, poorer fatigue resistance, and will damage wire cutters not rated for cutting mild steel wire. However at least its easy to spot as it is noticeably magnetic, and a small strong magnet will be attracted to it even through the insulation and outer jacket of cables. CCS wire may be legitimately used as the centre conductor of some types of high frequency coaxial cable, as the RF current only flows in the copper layer due to the skin effect, so the steel core doesn't matter electrically, and the higher tensile strength of steel is desirable. *PLEASE* don't use the electronics bench good small side cutters on CCS wire!
  • CCA (copper coated aluminium). It has higher resistance and much poorer fatigue resistance. This one is much harder to spot, especially if tin plated. For larger diameters of solid wire, you can see the freshly cut end is silvery rather than copper coloured, (or you can deeply scrape the side with a knife and see the same) and the weight per unit length will be lower than comparable copper wire. The easiest way of detecting smaller diameter CCA is by doing a flame test. Strip about 3 to 5 cm, untwist stranded wire and hold it in a lighter flame - small diameter copper wire will withstand the flame with brief exposure up to red heat resulting in only moderate discolouration and oxidisation. whereas CCA will rapidly 'flop' where the flame heats it and discolour severely: https://www.youtube.com/watch?v=rL5VUYe_uX8

Other wire info

  • Aluminium magnet wire is legitimately used in low cost appliance motors and power transformers, usually in low duty cycle applications. Its difficult to make a reliable electrical connection to it, near-impossible to solder, and the original termination is likely to be a crimp or spot weld. It tends to fail at the terminations in notably damp environments due to electrolytic corrosion.
  • Stranded electrical wire (with plain bundled strands i.e. not rope laid) has a CSA of approximately 90% of that of solid wire of the same overall conductor diameter due to the tiny voids between its close packed strands. For an accurate CSA measurement, it is not sufficient to calculate it from the overall diameter, as that is increased by twist, and also by possible gaps in the surface layer of strands, so you have to use a micrometer to measure the diameter of sufficient undamaged individual strands to get a good average, calculate the CSA of an individual strand, then multiply by the strand count. This is a PITA and is best avoided unless you need to verify that a wire meets specification.

Repair links

  • Sci.Electronics.Repair FAQ - "This site features Samuel M. Goldwasser's latest and greatest "Notes on the Troubleshooting and Repair of..." series of comprehensive repair guides for consumer electronics equipment and other household devices. There is also a great deal of other information of interest to the electronics hobbyist, experimenter, technician, engineer, and possibly even the dentist and poet. Included are the now quite comprehensive and massive "Sam's Laser FAQ", many new schematics, and links to over 1,000 technology related sites. In addition, there are a variety of documents from other sources on electronics troubleshooting, repair, and other related topics."

Electronics Forums

EEVblog Forum - run by electronics Youtuber Dave Jones - A good place to ask any electronics related questions, with a far wider pool of friendly experts than we can muster at RML

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