I'm not the leader here. I leave being "Der Fuehrer" to others. I am confident that the SNR will soon improve. Snowflakes melt away on the kitchen window.
Now, given this project is of zero interest to you, as it doesn't align with your prejudices and you have been told multiple times it will not pander to them either, maybe I can thank you for your contribution to SNR improvements?
Thor
I haven't looked at super caps in forever, I didn't realize they've come this far.
Jocko used to talk about 1/f noise for digital, clocks, D/A chips. This is the regulator he put together and used. I've done this in a number of circuits and have been happy with it. I don't have the gear to measure like he did so I can't comment.
Are you able to conduct an post measurements?
Mike
Jocko used to talk about 1/f noise for digital, clocks, D/A chips. This is the regulator he put together and used. I've done this in a number of circuits and have been happy with it. I don't have the gear to measure like he did so I can't comment.
Are you able to conduct an post measurements?
Mike
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Yes, me too. I had occasion and would suggest that latest generation low ESR super capacitors are a game changer for a lot in audio.
Yes. I still don't think he is right, but hey.
I have used similar in commercial products. More modern Op-Amp's can often dispense with the pass transistor.
I no longer have access to an AP, an QA box is best I can do. I cannot really measure noise with a charged super capacitor and a few ohm, I can directly at the linear lab power supply.
There are some papers where peeps measure ESR and noise as indicators of lifespan in heavy duty cycle use and I extrapolated from there. And yes, EOL supercap's are more noisy. But the noise frequency is so low, as is the level, its challenging for folks with much better equipment parks than little old me and measure over hours at a time.
Lil olde me figures that's "good enough for government work and audio".
How do you think a clock running from a 3,000,000uF/75mOhm capacitor that is fed DC via 2mH/4R DCR from a 317 regulators will do (given other local bypassing of course)?
This (~ 200nV |/Hz @ 200Hz - plus noise from a 317 has minimal 1/LF rise, it actually calculates from measurements to 150nV|/Hz):
filtered with this:
Less noise than a 5534 for sure. And nobody stops using something lower noise as regulator. Or bigger supercapacitors. It just takes longer to charge.
If I use two of my preferred 25F/2.7V capacitors the general graph looks the same, but we see ~ 12dB noise improvement over the above, -46dB @ 3Hz...
Here is what I use (the factory is in Thailand):
https://www.mouser.com/datasheet/2/129/du_e_p262-1889763.pdf
And yes, the specifications are pessimistic.
Past that, noise conversion of PSU noise into crystal oscillator phase noise is material, but much less than often assumed:
This is from a paper testing a discrete pierce oscillator at 10MHz. Seems 3,000nV|/Hz PSU noise (3uV |/Hz or 1mV of white wideband noise) still get's -146dBc flatband. Mind you, I struggle to recall an oscillator that clocked in at -140dBs at 10Hz offset. I'm happy if I see -90dBc. Maybe Jocko's magic crystal did better?
Thor
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Jocko never had any thing magic that I know of but he did sort. A lot. I have a couple crystals he sent me that are better than anything I've found elsewhere. Again, just sorted for the best.
Your numbers are the best I've seen.
Mike
Your numbers are the best I've seen.
Mike
Yeah, I mean he had a special (long discontinued) affordable crystal that even unsorted was pretty good and sorted even better.
Wow.
A Magic Crystal!
And you won't adam'n'eve it, from Magic Crystal Limited no less.
With an appropriate pricetag of only 350 Bux each and an MOQ of 5 (unless inflation and tariffs strike of course).
That that's a mere 700 Bux for a set of 2, if you can find use for the other 4 sets.
Ho Lee Chit!
I suspect for 16 Bit PCM 90dBc @ 10Hz may be tolerable. That's a Kyocera XO (blue line) that sells for 1.25 USD in singles:
A bit better than 90dB @ 10Hz.
Thor