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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 9th Dec 2023, 1:04 am   #41
Craig Sawyers
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Default Re: Au Revoir NE5534

Quote:
Originally Posted by Radio Wrangler View Post
Quote:
Originally Posted by knobtwiddler View Post
one member claimed that the part 'doesn't have a guaranteed noise spec'. What on earth does that mean?
Thermal and semiconductor noise is random, and therefore unpredictable.... So he was after something that Douglas Adams' philosophers demanded: "We demand rigidly defined areas of doubt and uncertainty!"

Any measurement of the averaged power of noise over a finite time leaves you with the uncertainty of whether you happened to hit a loud patch or a quiet patch and repetitions of the measurement will show scatter which diminishes as the averaging time is increased. Certainty takes infinite time, and once you've made one of those measurements, there is no time left in which to use the result

David
Indeed. The fact that the noise spectral density plots for the OPA210 go down to 0.1Hz is impressive. There is serious difficulty in going down that far. Jim Williams describes a system for measuring noise in the 0.1Hz to 10Hz range in his Linear Technology apps note 124 https://www.analog.com/media/en/tech...tes/an124f.pdf . He calls for a 1300uF 30V wet slug tantalum (currently £400), necessary for leakage reasons (less than 5nA), guard rings all over, dual FETs etc etc

Craig
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Old 9th Dec 2023, 2:07 am   #42
Radio Wrangler
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Default Re: Au Revoir NE5534

In the final analysis, there is no certainty. Everything we can have in finite time has to be processed noise. If we're lucky enough and foxy enough, we might still get something sufficiently well processed for our purposes.

Deep thoughts, to chuck in another Adams reference. As a mere oily rag-carrying engineer, I'd like to know what the specified tolerance on that '42' is.

David
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Old 9th Dec 2023, 2:31 am   #43
G.Castle
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Default Re: Au Revoir NE5534

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Originally Posted by Radio Wrangler View Post
In the final analysis, there is no certainty. Everything we can have in finite time has to be processed noise. If we're lucky enough and foxy enough, we might still get something sufficiently well processed for our purposes.

Deep thoughts, to chuck in another Adams reference. As a mere oily rag-carrying engineer, I'd like to know what the specified tolerance on that '42' is.

David
I'll calculate it:

Ask again in 7.5 million years, I should have your answer by then.
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