Products > Test Equipment
Cheap and Small Dynamic Signal Analyzer?
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gigavolt:

--- Quote from: electrolust on August 19, 2020, 01:25:17 am ---NanoDSA!

--- End quote ---

 ;D my thoughts exactly.  I'm surprised nobody has tried to do it yet, but I suppose that the combination of low frequency and low noise makes it difficult.
Berni:

--- Quote from: gigavolt on August 19, 2020, 09:54:05 pm ---
--- Quote from: electrolust on August 19, 2020, 01:25:17 am ---NanoDSA!

--- End quote ---
;D my thoughts exactly.  I'm surprised nobody has tried to do it yet, but I suppose that the combination of low frequency and low noise makes it difficult.

--- End quote ---

Guess more of a problem is that very few people actually want one. They are perfectly happy with there existing Rigol scope.

The low frequency and noise is not that much of a problem, you just pick a really nice opamp for the AFE. More of a difficulty is getting a spurious free response over the whole range. The noise floor is so low that even the tinyest of signals show up as a spike. This means a great deal of care must be taken in the shielding and PCB design to avoid any power supply noise or digital signals from getting in there and showing up. For example in my diy sound card design i had a LDO become just slightly unstable, not enough to cause obvious problems or a huge sine wave on the output when when poked with a scope, but it was singing enough to produce a small spike in the FFT, was quite a hunt to find where it was coming from.
KE5FX:

--- Quote from: Berni on August 20, 2020, 05:11:17 am --- For example in my diy sound card design i had a LDO become just slightly unstable, not enough to cause obvious problems or a huge sine wave on the output when when poked with a scope, but it was singing enough to produce a small spike in the FFT, was quite a hunt to find where it was coming from.

--- End quote ---

Let me guess, the part number contained the digits "1117"?
Berni:

--- Quote from: KE5FX on August 20, 2020, 06:39:51 am ---Let me guess, the part number contained the digits "1117"?

--- End quote ---

Forgot what it was exactly but it was some fancy pants high PSRR LDO whos job was to prevent crap from getting into the sensitive front end. So yeah... you had ONE job.

As for 1117.. yeah i don't even need a scope anymore to tell when one of those damn things becomes a oscillator. Last time i started wondering why my board is making a whistling sound even when there are no switching regulators on it. Turns out it was oscillating so wildly that the ceramic capacitors around it started signing loud enough to be noticed even in a not so quiet room.
2N3055:

--- Quote from: Berni on August 20, 2020, 07:23:01 am ---
--- Quote from: KE5FX on August 20, 2020, 06:39:51 am ---Let me guess, the part number contained the digits "1117"?

--- End quote ---

Forgot what it was exactly but it was some fancy pants high PSRR LDO whos job was to prevent crap from getting into the sensitive front end. So yeah... you had ONE job.

As for 1117.. yeah i don't even need a scope anymore to tell when one of those damn things becomes a oscillator. Last time i started wondering why my board is making a whistling sound even when there are no switching regulators on it. Turns out it was oscillating so wildly that the ceramic capacitors around it started signing loud enough to be noticed even in a not so quiet room.

--- End quote ---

"The singing regulator", new Broadway show..... LOL...
Yep, I avoid them too...
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