Chapter 12 Exercise: Visual Inspection of Commercial Products

a video streaming and recording device with the covers removed

This lab gives students a chance to apply things they've learned about designing for EMC to actual products.

Preparation: Students should read Chapter 12 of the book, including the suggested steps for performing a system-level design review. The products reviewed in this lab can be computing devices including laptops, printers, routers, and appliances. It is best to choose products that can be disassembled to expose the circuit boards and internal connections. It is not necessary for the product to be powered up or functional.

Equipment Required:

  • a selection of 3-5 commercial electronic products
  • ohm meter
  • magnifying glass

Procedure:

Step 1: For each product, students working in groups of 2 or 3 are asked to identify: 

  • the EMC ground structure
  • the location of relevant test ports/antennas
  • any design features whose sole purpose is for meeting an EMC requirement.

Step 2: Students working in groups of 2 or 3 are asked to answer the following questions.

  • What conducted emissions requirements is this product required to meet? What design steps were taken to meet this requirement?
  • What radiated emissions requirements is this product required to meet? What design steps were taken to meet this requirement? Could anything have been done better? If it were failing radiated emissions, what would be the likely reason?
  • What radiated immunity requirements is this product required to meet? What design steps were taken to meet this requirement? If it were failing radiated immunity, what would be the likely reason?
  • What transient immunity requirements is this product required to meet? What design steps were taken to meet this requirement?
  • What ESD immunity requirements is this product required to meet? Where are the likely ESD entry and exit points? Are there any obvious design steps that were taken to meet ESD requirements?
  • Does it have an earth ground? Was anything done in the product design for the purposes of ensuring safety?

Step 3: Students should answer the question, "If you had reviewed this design before anything had been built or tested, what design changes would you have recommended?"

Notes: 

It is good to have a variety of products from different industries, including products with and without a metal chassis and with and without an AC power connection.

After the labs have been turned in, it's helpful to have a class discussion of the various features identified by different groups.