On 11/2/19 2:28 AM, Jim Brown wrote:
On 11/1/2019 6:40 PM, Roger Parsons via TowerTalk wrote:
I would imagine that processing has improved since then, but this must
still be to some extent true.
You have a vivid imagination. :) I have measured data to prove that.
Also see N6RK's post. As luck would have it, I gave a talk to a Silicon
Valley club tonight on a very different topic, but afterwards fielded
questions about chokes from several engineers who had worked in
manufacturing. When I described my work described in an earlier post
about dealing with component tolerances, they nodded their heads in
agreement.
My first gig after college was at Motorola, which is where I first
learned that a circuit design has to work with every part that gets
plugged in to the circuit board, which means that the design has to work
with components with tolerances that you can and did buy.
I haven't checked the catalogs, but I'll bet that the tolerances for
parts intended for general purpose choking and transformers are wider
than those intended for building inductors. If a transformer core has a
higher mu than expected, it still works just fine as a transformer,
barring issues with loss and/or self resonance. Likewise, for something
being used as a lossy choke (as opposed to a resonant choke) you just
care that the loss is high enough - if it's twice as high as you
expected that's all the better.
On the other hand, if you're buying inductors for filters or for
switching power supplies, the core material has to be pretty consistent.
Since there *is* some crossover among applications for cores, you could
wind up using a poor tolerance core and having it work in a high
tolerance application, as a prototype.
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