When a solution is the solution, or: when an old dog meets an old dummy (load)

2/7/2010 8:14 AM EST

But sometimes, when you think you have seen it all, you haven't. I came across a fascinating article n the January 2010 of Power Electronics Technology, entitled "Testing Power Converters Using a Liquid-Rheostat Dummy Load". This article is not academic-theoretical or merely speculative: it has full analysis, rationale, construction details, performance graphs, and reference information on how to build and use an electrochemical cell as a dummy load. This is clearly a case where A solution is THE solution, so to speak. Apparently, this type of dummy load is not new at all (and how often do we even see the word "rheostat" in our electronics world?).

The other thing I found interesting was that the load in the story was not for some extreme power raring. Instead, it was for a 3.3 V, 40 W (continuous) output, which is a fairly modest power level. The conventional alternatives, according to the author, were too costly for his modest budget, and also would have required a complicated switching arrangement to set different test-loading levels, which would add undesired inductance and additional cost.

I'm not saying the liquid rheostat is the answer to you problems, But it's an interesting alternative, and interesting in itself as a creative solution (there's that word again!) to a specific test challenge.

Note: the two modest equations in the article did not show up in the online version–I saw the article in that ancient medium of print, where they did appear–so here they are:

R = (ρ × L)/A

R = d/(δ × A)

Enjoy getting out of your dummy "comfort" zone!♦