Testing

Injection of audio frequency ripple on equipment input power conductors has a long history, going back to 1953 (MIL‑I‑6181B) in the United States military, and at least as far back as 1961 in commercial aviation (RTCA/DO‑108). Audio frequency injection has been accomplished by inserting the secondary windings of a coupling (isolation) transformer in series with the power conductor to the test sample. While various transformers had been used prior to the 1960s, one has become standard since 1963. That Model is the Solar Electronics Model 6220, designed in 1962 and accepted by the United States Air Force in 1963 as being superior to previously used injection transformers. [1]

Rising above the tidal marshes of Southern New Jersey stands a red and white antenna tower shadowing a World War II era radio shack. The marsh was a simple mosquito nursery in the 40s when the first modest building—a cinder block foundation and stick-framed walls— was erected as part of a string of radio stations that formed a wartime network on the East Coast. German subs prowled the waters just off the shore of Cape May which hosted just a few houses and one general store with peeling gray paint and sway-back roofline.

ENERGY STAR has created a completely new system of requirements and procedures for qualifying energy-efficient products. Navigating the new routes to qualification can be a challenge, given the multiplicity of newly defined requirements for testing, certification and verification. What are Recognized Laboratories, Certification Bodies and Accreditation Bodies? What roles do they play in the process? Can manufacturers still perform their own product testing for qualification? This article will chart the landscape and describe how to choose the fastest and most economical route through EPA’s Enhanced Testing and Verification Program.

Spectrum analyzers and scanning receivers are widely used in EMI laboratories today. Their use for measuring both narrowband and broadband signals requires specific understanding of certain instrument and signal characteristics in order to correctly interpret the displayed results. This article explains methods for the discrimination between narrowband and broadband signals and provides guidance for the proper operation of test instrumentation.

There are numerous reasons for the use of an external test laboratory by organizations developing, manufacturing or marketing electric or electronic products. These reasons may include lack of or limited testing capability, scheduling conflicts within the organization, etc. Whatever the case may be, the proper selection of an external third party test laboratory is critical since the test results may be used to demonstrate product compliance or to verify changes to a product design.

Many sources recently have reported that electrical failures to components previously classified as EOS (Electrical Overstress) are instead the result of ESD (Electrostatic Discharge) failures due to charged-board events (CBE) [1,2]. A charged printed circuit board assembly stores substantially more charge than a discrete device as its capacitance is larger. A subsequent discharge of the board assembly results in increased current for that event - versus that of the discrete component. Consequently, a device’s CDM (charged device model) rating is lowered when mounted in a printed circuit board (PCB). In an attempt to get a feel for just how much it is lowered, we conducted CDM stress tests on components in discrete form, and again after insertion into larger and larger sized pc boards. We found that the CDM ratings are lowered dramatically!

Electromagnetic disturbances can greatly influence the performance of equipment and the functional safety of systems. Consider the current problems we hear in the news with unintended acceleration in some vehicles. While this complication’s true cause may never be determined, analysts have theorized that electromagnetic disturbances could play a large role. Due to the amount of electronics and ever changing technologies found in today’s automobiles, unintended acceleration is only one of many examples of unwanted anomalies that could occur due to an EMC issue. Automakers are faced everyday with the risk and associated liability that could come with a problem such as this once the vehicle is on the street with the consumer. That risk is why the automakers over time have had to develop specific test standards that relate to the EMC concerns of their vehicles and enforce their suppliers to meet them by way of specific test plans. The automotive industry is just one example of how EMC can relate to the functional safety of a product as guided by IEC TS 61000-1-2: 2008.

In earlier articles in this publication we have discussed the charged device model (CDM) testing of small devices. In the first article we demonstrated that the peak current for small devices does not become vanishingly small.¹ The commonly held belief of vanishing current for small devices was shown to be an artifact of measuring the current with the 1 GHz oscilloscope² specified in the JEDEC CDM standard.⁶ The second article explained various ways to make CDM testing of small devices more reliable with the use of small surrogate packages, or the use of templates to hold the device during testing.³ In this article we will show how insight can be gained into the CDM testing of small devices using a simple three capacitor circuit model.^{4, 5}

The 21st century as we know it, truly reflects the age of technology. Every aspect of life today is encompassed by the use of some sort of microprocessor based electronics intended to simplify tasks, to improve processes, and improve efficiency. Electronics are used to communicate with loved ones, manage finances, fly aircraft, even save lives. As greater advances in technology are achieved, electronics are found controlling more important safety critical functions at an exponential rate. Although electronics have provided us with obvious benefits, the increasing reliability on electronics has elevated our vulnerability to the effects electromagnetic pulses.

Wireless alliances like Wi-Fi and ZigBee certify wireless devices for interoperability which to the end user provide a confidence level of smooth operation between these devices from different manufacturers. For instance this level of interoperability is necessary (but not sufficient) to ensure communications on WLAN Wi-Fi segments containing an Access Point (AP) and a number of wireless client cards. The same concept applies to ZigBee networks where interoperability gives a confidence level for ensuring operation of devices such as a light bulb and a switch, an RF4CE remote control and paired TV, DVD player or set top box, but also insufficient to assure seamless operation of the network over time and under variable environmental conditions especially in demand-response time critical scenarios.