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Broadly speaking test instruments often do similar things that some consumer devices do as well, but 1) with greater precision, accuracy and stability 2) over a

Broadly speaking test instruments often do similar things that some consumer devices do as well, but 1) with greater precision, accuracy and stability 2) over a much wider range of parameters. For example, a spectrum analyzer is similar to a radio receiver, but the SA usually covers a much larger rage (typically 9 kHz - 1.8, 5, 12 GHz), the SA can handle a huge range of input powers (typically something like -1xx to +20 dBm), and it can accurately measure power levels at all frequencies, has a variety of filters and analysis functions and so on. The RF section of some of these is actually mostly made of standard COTS parts - input assembly (these use very high grade connectors because of the repeatability requirements), programmable precision attenuator, mixer module, YIG LO etc. -- except all of these are high precision, RF devices, which simply cost a lot of money. The 80/20 rule applies as well. Well, maybe more like 60/40. An SDR can get you most of the stuff a proper SA can do for a fraction of the price (and can do some things an used SA from the 80s or 90s cannot do). A very good audio interface can serve as an audio analyzer, given the right software. A common pattern is that you can get the capabilities to do something, but not the accuracy of a real test instrument.

gmueckl 7y ago
One aspect that drives cost is that high precision circuits often need a few parts that have tighter tolerances than the typical 5% or 1% that are usually good enough for 99% of use cases. And these parts are a lot more expensive.
- joshvm 7y ago
  It's worth mentioning that often parts aren't manufactured to be high precision variants. That would be extremely expensive. What happens instead is the parts get measured and "binned" by how close to spec they are. In a large enough sample, statistically a few parts (even with an inaccurate process) will be perfect. The best ones are sold as A grade, etc. This is pretty common for thinfs like resistors, but even CPUs and RAM are binned by their overclock performance as there's some randomness in production.
  - stan_rogers 7y ago
    When I were a wee lad, we used to machine passive components to value (sometimes the "whole thing", sometimes a companion trim piece). There's no economy of scale to be had there, and binning won't help all that much because it's the installed value that matters, not the loose part value.

gmueckl 7y ago

One aspect that drives cost is that high precision circuits often need a few parts that have tighter tolerances than the typical 5% or 1% that are usually good enough for 99% of use cases. And these parts are a lot more expensive.

joshvm 7y ago
It's worth mentioning that often parts aren't manufactured to be high precision variants. That would be extremely expensive. What happens instead is the parts get measured and "binned" by how close to spec they are. In a large enough sample, statistically a few parts (even with an inaccurate process) will be perfect. The best ones are sold as A grade, etc. This is pretty common for thinfs like resistors, but even CPUs and RAM are binned by their overclock performance as there's some randomness in production.
- stan_rogers 7y ago
  When I were a wee lad, we used to machine passive components to value (sometimes the "whole thing", sometimes a companion trim piece). There's no economy of scale to be had there, and binning won't help all that much because it's the installed value that matters, not the loose part value.