Blog - Category Archives: Engineering Notes
Darrel Baker

“How much does it cost to build one of these?” It depends… When an aerospace customer needs a new printed circuit assembly built for a legacy system, invariably their first question is “how much will it cost?” Building a new assembly can be relatively straightforward—or impossible—to accomplish. It depends. Is it build-to-print? Assuming the engineering dataset is complete, and you can wrestle it to the ground, build-to-print can be cost-effective. Reverse engineering, or reproducing the engineering data set and getting regulatory acceptance, is by far the costlier path. Here I’ll address some of the challenges of build-to-print for legacy circuits.     New Old Stock. The first consideration is whether the components called out in the drawing package are still available. And make sure the available stock is actually new, … Read More +

Richard Lundin

I had a conversation with a potential client several months ago about doing a redesign of their newly introduced product. Since they were not reengaging the initial design firm, I asked why. Their reasoning in short was that the product did not behave as they expected it to under changing conditions external to their product, and thought the design firm should have designed for that. I asked what the product specification called for under those circumstances and was asked “what is a product specification?” That answer said it all; the process went wrong at the beginning. That’s not to say that starting with a napkin sketch won’t work, but a clear and detailed product specification is the mainstay of a successful product design. It saves development time, money, and can … Read More +

Barbara Stilwell Baker

Mixed-discipline teams are key to complex product development. I wrote about this more than twenty years ago, and it’s still true today. In my behind-the-scenes role at Stilwell Baker, I don’t often go to customer’s sites. But recently I had the opportunity to join the field trial for a new prototype we’re developing. This project is what we call a “rescue.” Our customer’s previous attempt to develop this product (with another company) failed because they didn’t have the diverse expertise necessary for a complex design. This is a great project for Stilwell Baker because of the diverse skill sets and deep technical knowledge required to resolve the design issues. The high voltage and digital control circuitry required a complex blend of hardware, firmware, and mechanical engineering all working concurrently in support … Read More +

  Happy New Year! We are starting 2013 in our new Lake Oswego facility and the engineers are enjoying the lab. It’s a large space, designed specifically for use as a development lab, and best of all, it’s located close to the engineers’ desks. Two thermal chambers help us quickly identify and fix potential product issues at extreme hot or cold temperatures. The chambers have 7.7 and 12.3 cubic feet internal space, and the computer programmable controllers safely run them in our temperature test range from -60 degree C to +125 degree C (-76 degree F to +260 degree F). We have already detected two design issues at below -20oC that have resulted in design improvements, thereby preventing field failures. The lab has plenty of standard tools, but my favorite … Read More +

Picoamps at kilohertz anybody? I spent a good chunk of my career working for a major automatic test equipment (ATE) manufacturer, mostly designing and testing analog instrumentation. One module found on most cards in an ATE system is a parametric measurement unit (PMU), which measures DC parameters – voltage or current – on a pin of a device under test (DUT) in response to the complementary stimulus – current or voltage.  Because time = cost during IC testing, as in so many industrial arenas, “DC” must be taken with a grain of salt.  These measurements are the slowest single measurements made on a pin, so there is always pressure from the market to make them as fast as possible. Still, a few milliseconds is not uncommon. On the other hand, … Read More +

Down a Rathole?

Many people in the high tech industry have heard the expression down a rathole, but which rathole? Many groups use this phrase, but with very different meanings. The literal description of a rathole is a place where rats dig a hole through ground, wood, plaster, or even concrete to get into their nests, which are often dirty, small, and cluttered. This leads to the use of the phrase to describe a person’s living quarters which are dirty, small, and cluttered: like a bachelor’s apartment.   In the oil drilling industry, a rathole is a vertical shaft drilled near the main well hole, or a hold in the floor of the drilling platform used for temporary storage of the Kelly (the hardware that connects the hoisting cables and the rotating drill … Read More +

Hey, buddy, wanna buy an H-bridge?

Have we got a deal for you! Bridges have come a long way from the old tree fallen across the creek, with man-made bridges getting people safely over all kinds of obstacles. Bridges connect cities and states separated by rivers (like Portland-Vancouver), enable simple and safe commerce and family travel, provide habitat for trolls, and are just plain fun to ride across on your bike. Bridges can be expensive or cost effective, beautiful and elegant, or clunky/bulky and ugly, safe or wobbly. Everything depends on the designer and the builder. Bridges are also an important circuit topology in electrical/electronic circuits.  The wide variety of bridge circuits include: the Wheatstone bridge used in sensors and measurement tools the diode bridge rectifier widely used in power supplies converting AC current to DC … Read More +