Basic Circuits, Part Deux

When calculating power exhausted through a resistive element, remember … power varies directly with the square of the voltage and inversely with the resistance.

Therefore, if your resistance has a tolerance of ±5%, your input voltage can only have a tolerance of ±sqroot(5) if you’re going to meet that power output required in your specification.

The “We’re in tolerance! No, you’re not!” discussion went back-and-forth before about five minutes before I made that minor note.

You see, that MSMS education taught me something.

Mrs. Perry would be proud!

Also, isn’t it a bit weird for the same quality group that will sign off on product testing to be the individuals actually running the test? It’s a matter of integrity tied up in checks-and-balances.

[Somewhere in West Tennessee, my dad probably just choked on his water, reading that.]

I love this job!


  1. Cough . . . Glub . . . Sputter . . .

    As you often say, “It’s all Physics.”

    What disturbs me, as it does you, is the same folks performing the critical tests and then verifying they are correct.

  2. You mean it’s not good for the same engineer to design the product, decide what needs to be tested, test it, and decide if the results actually are good????

    If only we could get someone hired into my group to provide more of a division of the responsibility in our product development.

    For us, the requirements are supposed to be given to us by marketing (never happens). After that, we the design engineers design and implement. We then also are expected to write the test procedure to verify our design (this is the part where we can’t someone hired in). Then the tests are run and documented. (I can usually find a tech to at least half-way run my tests for me)

    One of these days the CS world will get with the times and we’re start designing and testing things to the same sort of standards that hardware is (you know, using some tolerances)

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