Years ago, a customer needed a transformer for a battery-driven muscle stimulator. The transformer stepped up the voltage from the battery and drive circuitry and then presented it to adhesive pads on the skin where the current would cause the underlying muscle to contract.
The “defined” muscle load was 1k ohms and we were asked to create a transformer with as high an output as possible. This appears to be a classic case of impedance matching to transfer the most power, but the difficulties stemmed from the fact that the battery, PCB traces, and transistor impedances were unknown and were likely to remain so. How would we optimize the transformer for maximum power transfer with an unknown source impedance?
Ah, but we did know the exact parameters of the transformer, so I suggested that we test the circuit with a varying output load. By determining the optimum output impedance for maximum power transfer and applying the transformer parameters we could empirically determine the total aggregate source impedance. Once the source was known, tweaking the transformer to give the maximum output into a 1k ohm load was simple (relatively speaking). Sometimes you need to fall back to the very basics of power transfer to see the big picture.
Jim Mettler is the engineering manager at Triad Magnetics. His career has spanned 27 years of magnetics design in applications from doorbells to satellites and everything inbetween.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 5
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This radio show will show what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
12 
