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Old 9th July 2012, 08:50 PM   #21
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Quote:
Originally Posted by qusp View Post
i'm aware of all the decades old comparisons jackinnj, what sort of a comparison is that? 7Ah vs Jung reg? most Jung regs are severely current limited vs LiFePO4, a single $12 cell is 3v3 @2500mAh we are talking about clocks here right? thats over 30hrs minimum right there and you can then charge it in less than 1hr show me what sort of super reg you can build for $12, show me its current rating
I think jackinnj's point is more that a super regulator can give you a lower output impedance and just as low noise than a battery. Therefore if properly configured and implemented the super reg will give you comparable performance, but will not require charging. Charging to me would be a major pain in the behind, I tried battery powered a few years ago and it frustrated me no end. The only way to get around that would be to include some charging system that kept the batteries topped off so I'd never end up with them going flat on me during a listening session - this obviously adds in cost. From my point of view the super reg just seems more convenient.

I don't know strictly how much current a super reg can provide, but it can be quite a lot. I easily pull 500mA+ out of mine, but if you use an LM317 as a pre reg, then it acts as protection vs over current and short circuit, so providing you keep the pass transistor suitably cool you can probably get ~1.5A out of one. I don't know why this is important though when the clock will only draw a few tens of mAs.
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Old 9th July 2012, 09:43 PM   #22
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Quote:
Originally Posted by qusp View Post
show me what sort of super reg you can build for $12, show me its current rating
With an LME49710 as the error amp, and a D44H11 pass transistor you're probably talking less than $10 for parts.

I've used the Jung regulator to about 600mA.

I'm not anti-battery (did I say I was) -- they have a smooth, non quirky aspect to the sound as a product of their use. They have great rejection of low frequency (under 50Hz) energy.

Guess I should look at a jitter histogram...
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Old 9th July 2012, 10:58 PM   #23
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Default Guys...

It appears that you are not reading the details of the posts. No one has ever established, to my knowledge, that any regulator will have a lower output z than a LiFePO4 battery. So far we have seen data only for older battery tech, which is not what qusp proposed.
Additionally, cost is not really a factor, but even if it was, one needs to consider the following costs for an AC based supply: transformer+diodes+smoothing caps+pre-regulator+local regulators of your choice. I am already using this set up, with a dedicated transformer for the oscillators power supply.
A battery requires: a single LiFePO4 cell for each oscillator, battery management, a charger, and a switch and jack for charging. I think the costs are going to be close enough not to worry about anyway, if anything the AC supply will be more.
For powering oscillators, high current output is not required, so ultimate current capability is not an issue. Low noise is crucial, and isolation from the rest of the DAC is crucial as well. Some seem to believe that very low output z is needed, (and I suspect that a LiFePO4 cell meets this need) but, Demian Martin does not seem to think so: see his dedicated oscillator regulator design in the Ian's FIFO thread. I have a lot of respect for Demian, such that I think he probably knows what he is talking about. Additionally, no regulator is going to have low impedance at MHz range clock frequencies anyway, right?

This thread is about powering oscillators, the merits of powering other circuits with batteries is OT here. I feel that qusp has presented an interesting alternative worth considering for powering oscillators.

Last edited by barrows; 9th July 2012 at 11:00 PM.
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Old 9th July 2012, 11:35 PM   #24
sandyK is offline sandyK  Australia
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Hi Barrows
FWIW, I use a +-15V LM317/LM337 supply with my highly modified MF X-DAC V3. It is further smoothed by a JLH PSU addon , which is as you are aware, is a variety of Super Regulator, but without a voltage drop.I then follow this by a +5v version of a similar topology to the PFM "Flea",which uses a highly filtered reference voltage derived from the higher voltage supply, then via an opamp. This supply then goes via the existing ferrite beads and ceramic bypass circuit to the oscillator module. I believe that it's the extremely low noise stable reference, that matters more than just a very low output impedance supply.
Just as changing from a Vanguard 1PPM oscillator module to a .3PPM Vanguard oscillator made a worthwhile audible improvement, so did powering the .3PPM from this opamp circuit give a similar improvement over the same highly filtered supply followed by a 7805. The further audible improvements were especially evident with high resolution material.
Regards
Alex
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Old 9th July 2012, 11:39 PM   #25
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Quote:
Originally Posted by barrows View Post
It appears that you are not reading the details of the posts.
I for one read the entire thread.

Quote:
Originally Posted by barrows View Post
No one has ever established, to my knowledge, that any regulator will have a lower output z than a LiFePO4 battery. So far we have seen data only for older battery tech, which is not what qusp proposed.
This is irrelevant because even on a theoretical level, both potentially will have an output impedance that is extremely low.

Quote:
Originally Posted by barrows View Post
Additionally, no regulator is going to have low impedance at MHz range clock frequencies anyway, right?
Neither is a battery, track/trace/wire inductance takes over, it's one of the reasons we use decoupling capacitors.

Quote:
Originally Posted by barrows View Post
This thread is about powering oscillators, the merits of powering other circuits with batteries is OT here. I feel that qusp has presented an interesting alternative worth considering for powering oscillators.
One advantage of the super regulator vs the battery is that you can use the regulators remote sensing ability to lower the seen impedance of the powered device beyond that of the traces/wires. This is one of the areas where the super regulator actually excels - powering a single device only.
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Old 9th July 2012, 11:46 PM   #26
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Default Exactly...

"Neither is a battery, track/trace/wire inductance takes over, it's one of the reasons we use decoupling capacitors."

Exactly my thinking, and why I do not think that super low z out should be the determining factor for an oscillator power supply. My suspicion is that low noise, and complete isolation from the rest of the DAC, are the desirable factors. Seems like a LiFePO4, decoupled by .1uF right at the point of load, could be a very good approach. Minimizing the lead lengths from the battery may be worthwhile as well.
Anyone know if there are any known resonance factors with batteries-leads-caps?
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Old 10th July 2012, 12:35 AM   #27
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Quote:
Originally Posted by barrows View Post
It appears that you are not reading the details of the posts. No one has ever established, to my knowledge, that any regulator will have a lower output z than a LiFePO4 battery.
The "6 Moons" review of the Red Wine battery supply said that Zo was 20milliOhms -- one has no idea how they accounted for the inductive portion.
I've read several papers by Chinese cell manufacturers and they specify Zo of 20 to 100milliOhms.

The Jung regulator measures Zo under a micro-Ohm -- this is because the bandwidth of the error amplifier is very high, and Zo is inversely related to bandwidth.

Send me an LiFePO4 and I will measure the Zo from 1Hz to 40MHz free of charge. I'll even send the battery back.
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Old 10th July 2012, 12:31 PM   #28
marce is offline marce  United Kingdom
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Barrows has hit the nial on the head, PSU choice is secondary to porper decoupling and preferably power planes with interplane capacitance. Though 1uf is not a decoupler but a reservoir cap, ebven a 0.1uf ceramic in a 0402 package is only good for 12MHz. The initial charge come from capacitance within the device, then the board interplane capacitance, then the small decouplers, these are then filled up by the reservoir caps and finaly the PSU fills themup. This is the MAIN function of decoupling capacitors to provide the charge required for a circuit to switch. With todays fast rise time devices, power planes are a must, and planear capacitance is critical and becomes more so the higher the frequency. For clocks I would recomend some very small COG caps(pFs) with 0.1uF X7R's as intermediate reservoir caps, then some 10uF X7R then a few larger elecs or tants.
Using some software similar to this:
http://www.algozen.com/DS_CADSTAR_LT...2011_10_05.pdf is an eye opener, and generaly shows how bad rules of thumb we have all worked to for years are.
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Old 10th July 2012, 03:29 PM   #29
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marce. I am using Crystek CCHD oscillators. If one happens to look inside one of these, it is clear that Crystek has supplied final decoupling internally. Must be time to look at the app notes from Crystek on using these parts. I suspect that .1 uF at the power pin may be totally adequate considering the additional onboard decoupling/filtering.
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Old 10th July 2012, 03:45 PM   #30
marce is offline marce  United Kingdom
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Yes, this is happening more often (Virtex 5s + have 0201 decouplers on the interposters) as people are realising that standard decoupling does not work like we think. Just spent an exciting week in Munich looking at this and SIV (signal integrity) software and discussing power delivery systems and decoupling. it was all digital and Rf based.
My recomendation for the COG comes from some high rel designs (mil) where we did extensive EMC and signal integrity testing. We were using oscillators, and the best results for both signal integrity and EMC were with a very small COG next to the pins, with X7Rs further out. Note that it was only on oscillators that the COG's were beneficial, elsehwere better results were achieved using X7R caps as we could get smaller packages (0201's have half the inductance of 0402's). Using 0402 devices you can halve the inductance by using via in pad, though this can be rather costly for DIY as you have to have them filled and capped.
The excellent RF operation of small value COGs is benefitial for clock decoupling, the smallest package you can find.
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