ROBUST ELECTRONIC DESIGN
Electronic Equipment
John R. Barnes KS4GL, PE, NCE, NCT, ESDC Eng, ESDC Tech, PSE, Master EMC
Design Engineer, SM IEEE
December 19, 2010
jrbarnes@iglou.com
Companies and organizations develop equipment for their internal use,
typically to:
- Help develop products.
- Exercise prototypes to prove that they meet the company's standards and
applicable national/ international standards.
- Stress-test prototypes to prove that they have sufficient design margin,
for economical manufacturing and reliable operation in the field.
- Manufacture/test/repair the products or critical subassemblies.
- Diagnose problems in the field.
The design requirements for equipment tend to be moving targets, constantly
evolving as the associated product(s) are tweaked, enhanced, and redesigned:
- Progressing through development.
- Accumulating manufacturing experience.
- Receiving feedback from users and Field Service.
Because we usually build only one or a few copies of each piece of equipment,
we can afford to build in some extra capabilities up front to cover the
uncertainties associated with the project. For accurate measurements we want
the equipment to be at least 3 to 10 times as accurate as the parameters we
are trying to measure. A well-integrated development environment with
powerful debugging tools can greatly reduce programming time, even if the
resulting code is somewhat inefficient. To keep from slowing down development
by running into artificial limits, we usually want to provide for:
- 10 to 20% more input/output points than we expect to need.
- Twice as much code, data, and stack memory as we expect to need.
- Twice the processor speed as we expect to need.
The safety requirements for equipment are usually based on the company's/
organization's internal standards and voluntary industry standards. Since we
control the equipment, who uses it, and when/ where/ how it is used, we can
provide safe working conditions by a combination of:
- The inherent design of the equipment and process.
- Guards over dangerous subsystems.
- Warning labels.
- Operator training.
- Personal protective equipment.
- Special tools.
- Proper operating and maintenance procedures.
- Controlling the environment around the equipment, including power
quality, taking precautions against electrostatic discharge (ESD), and
keeping interfering devices well away from the equipment.
We can get by with fairly skimpy parts/ materials specifications for
equipment, because we usually buy enough for the life of the program in one
lot. Similarly, the manufacturing/ test documentation for equipment may be
sparce, perhaps some sketches and an engineering notebook, because most of
the assembly and debugging will be done under the direct supervision of the
equipment designer. Repair and service documentation should be fairly
complete, because the equipment designer may not be available when they are
needed.
Because of the small quantities needed, we will usually be limited to
off-the-shelf power supplies or product power supplies for equipment. Moving
equipment to another country may require redoing some of the primary wiring:
- Changing line cords.
- Changing input connections to power supplies.
- Adding a step-up/step-down power transformer.
Flexibility tends to be more important than an "optimum" design, letting us
develop electronic equipment quickly while holding down the engineering and
programming costs. In many cases we will adapt/ enhance a previous design
instead of doing a new design from scratch. We also tend to be very
conservative in our design and selection of subsystems, parts, and materials,
to minimize the risks associated with the project. In general, we want to
limit our custom development of equipment to:
- Adapters to mate general-purpose equipment to our product(s).
- Special requirements that can't be met by off-the-shelf equipment.
dBi Corporation was a
one-man ISO 17025-accredited electromagnetic compatibility (EMC),
electromagnetic interference (EMI), and electrostatic discharge (ESD) test
house (testing laboratory) based in Lexington, Kentucky. dBi was
founded in 1995 in Winchester, Kentucky by Donald R. Bush, shortly after he
retired from 30 years service with IBM Lexington's/ Lexmark's EMC Lab. John
R. Barnes bought dBi in 2002 after Don's death, and moved the company
to Lexington, Kentucky. John closed dBi at 11:59pm EDT on September
30, 2013, because ObamaCrap has increased our operating expenses to the point
that we can no longer afford to remain in business.
We'd like to thank all of the clients who chose us to test their products from
1995 to 2013. Below is a brief summary of dBi's accomplishments during
the 18 years we were in business.
From 1995 to 2001, under Don Bush's ownership and operation, dBi:
- Did the official approval testing of 141 products developed by 20
client companies.
- Did the official FCC/ Industry Canada (IC) Verification and Declaration
of Conformity (DoC) testing of 92 products.
- Did the official FCC/IC Certification testing of 15 products.
- Did the official CE Marking testing of 100 products.
From 2002 to 2013, under John Barnes' ownership and operation, dBi:
- Tested 389 products and 2 testers developed by 44 client companies.
- Did the official approval testing of 357 products and 2 testers, getting
all but 5 of them to meet all of the FCC, Industry Canada
(IC), CE Marking, C-Tick, and Regulatory Compliance Mark (RCM) standards
and requirements for their desired market areas.
- Did the official FCC/IC Verification and Declaration of Conformity (DoC)
testing of 296 products.
- Did the official FCC/IC Certification testing of 24 products.
- Did the official CE Marking testing of 271 products and 2 testers.
- Did the official e-Mark testing of 3 products.
- Did the official Australia/New Zealand Verification testing of 170
products.
- Served as an expert witness on electronics in three lawsuits.
Last revised December 19, 2010.
