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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
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Old 14th June 2018, 12:09 PM   #431
iancanada is offline iancanada  Canada
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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
Quote:
Originally Posted by TioFrancotirador View Post
@iancanada
Ian,

How about the following scenario:
What is your typical listening session time? Hours?
What is the acceptable time for your DAC to power up? Minutes?
What if you have Super Capacitor PSU for your DAC that would charge quickly (minutes) but only from time to time and then discharge for hours …

Would two BIG 3000F Maxwell cells meet those requirements? Those two could be charged with dozen of Amperes in minutes and discharge with hundreds of miliAmpers in hours with assumption to allow some small voltage drop ~0.5V. In such case discharge to charge ratio is around ~1:60 (one minute charging to one hour of discharging in this case). I assume voltage drop here from 5.4V to 4.9V, but could be lower down to acceptable local LDOs input levels.

No switching here. The use case here is like with Power Bank, but with quick automatic charging only from time to time. Most of the time (98% ?) the DAC would be powered with SuperCaps. Short charging periods could be indicated with some LED, so you would know when to plug the ears

For me something like this seems to be far easier to build, if one accepts those short charging periods.

What do you think guys?
Thanks TioFrancotirador, it's a very good point.

Still need relays to turn on/off the charger. The key difference would be switching every 10 minutes or turning on/off every one hour if you don't want to stop music.

But this arises me another idea: Design the charger with smart, to charge the ultracapacitor only during silence time between music, and keep ultracapacitor disconnected from charger while music is playing.

Please let me know what do you think.

Regards,
Ian
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Old 14th June 2018, 12:29 PM   #432
TioFrancotirador is offline TioFrancotirador  Poland
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Quote:
Originally Posted by iancanada View Post
Thanks TioFrancotirador, it's a very good point.

Still need relays to turn on/off the charger. The key difference would be switching every 10 minutes or turning on/off every one hour if you don't want to stop music.

But this arises me another idea: Design the charger with smart, to charge the ultracapacitor only during silence time between music, and keep ultracapacitor disconnected from charger while music is playing.

Please let me know what do you think.

Regards,
Ian
Well I thought in this case switching could be done not at capacitors level where relay could be welded because of high amperage, but at 230V, where amperage is lower. Kind of plug and unplug mechanism or maybe at DC/DC converter level at least. Unless not amperage, but wattage matters here so it does not matter

Your idea about DAC informing charger to work on: mute, no PCM nor DSD signal or simply no music is also interesting … however this narrows down usage of such PSU to only unit capable of sending such information … needs more thought on this one …
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Old 14th June 2018, 12:46 PM   #433
iancanada is offline iancanada  Canada
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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
Quote:
Originally Posted by TioFrancotirador View Post
Well I thought in this case switching could be done not at capacitors level where relay could be welded because of high amperage, but at 230V, where amperage is lower. Kind of plug and unplug mechanism or maybe at DC/DC converter level at least. Unless not amperage, but wattage matters here so it does not matter

Your idea about DAC informing charger to work on: mute, no PCM nor DSD signal or simply no music is also interesting … however this narrows down usage of such PSU to only unit capable of sending such information … needs more thought on this one …
We don't need to worry about relay contacts at all, I have tons of way to protect them from welded.

The only thing need to be focused is how to get the best sound quality form the performance of the ultracapacitor power supply.

I like the idea for using big ultracapacitor (>3000F) to eliminate the bank switching, but how to charge it has to be very smart.

Regards,
Ian

Last edited by iancanada; 14th June 2018 at 12:50 PM.
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Old 14th June 2018, 01:05 PM   #434
TioFrancotirador is offline TioFrancotirador  Poland
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Quote:
Originally Posted by iancanada View Post
We don't need to worry about relay contacts at all, I have tons of way to protect them from welded.

The only thing need to be focused is how to get the best sound quality form the performance of the ultracapacitor power supply.

I like the idea for using big ultracapacitor (>3000F) to eliminate the bank switching, but how to charge it has to be very smart.

Regards,
Ian
So maybe hybrid solution, switching between BIG Caps (6000F) 98% of time and some linear or switching 5V regulator for the rest 2% of time with some information to the user whether is on battery or on regulator.
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Old 14th June 2018, 01:28 PM   #435
ofswitched is offline ofswitched  Taiwan
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Quote:
Originally Posted by iancanada View Post
We don't need to worry about relay contacts at all, I have tons of way to protect them from welded.

The only thing need to be focused is how to get the best sound quality form the performance of the ultracapacitor power supply.

I like the idea for using big ultracapacitor (>3000F) to eliminate the bank switching, but how to charge it has to be very smart.

Regards,
Ian
Ultracapacitor is very sensitive to voltage changes, you will still need LDOs to achieve a stable voltage.
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Old 14th June 2018, 08:09 PM   #436
markusA is offline markusA  Sweden
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Default ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi

How about going for a simple solution? Switch between regular psu and “silent running” for quality listening?
I use my Pi for more than just serious listening and for watching tv shows or movies, it’s not overly critical to have super clean power.
This way you could also toggle the power while you go and make coffee, using the down time for charging.

P.S. In my case it’ll probably be more like 1.5A continuous draw since my RPi has a hdd hooked up.
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Last edited by markusA; 14th June 2018 at 08:12 PM.
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Old 15th June 2018, 12:40 PM   #437
Abartels1965 is offline Abartels1965  Netherlands
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Guys,

I have used my principle in my dac/streamer 3/4 year and was very pleased with it.
Switching between the banks is not a problem at all, and charging is VERY simple when using DC-DC converter which converts 19V laptop adapter to the needed hosts voltage. Since it does CC first, then CV, and it stops charging when ready, even with 100F you can listen about half an hour, so switching once half an hour.

Don't make too big a deal of it, it's just that I had to preset runtime with a timer for switching the banks because of no voltage sensing circuit, that is the thing I would want to add at my system.

About best sound quality:

Choose relays with the lowest contact resistance, I chose relays with bifurcated contacts, with two sets of contacts which I use in parallel, so half the resistance of the initial (50mOhm) contact resistance.

I would still prefer mosfets, not only because of mechanical silence, but for low RDS-ON ( resistance). and I can't imagine that Collector Emitter can't galvanic isolated from each other, not sure how to switch GND with mosfet though….

I have 50 relays switching every 30 minutes, it is not a huge clicking sound, but my listening distance is 7 meters. I can imagine if listening distance is 3 meters switching noise can be a pita.....

Just my 5 cents....


Alex
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Old 15th June 2018, 12:43 PM   #438
Abartels1965 is offline Abartels1965  Netherlands
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I wanted to show schematics picture, but it doesn't work, not sure why….

Please open the link at the bottom of this message, it's the fourth picture!
Sorry for the bad drawing, but it explains….


Cheers,


Alex
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Last edited by Abartels1965; 15th June 2018 at 12:46 PM.
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Old 15th June 2018, 12:53 PM   #439
Abartels1965 is offline Abartels1965  Netherlands
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Quote:
Originally Posted by ofswitched View Post
Ultracapacitor is very sensitive to voltage changes, you will still need LDOs to achieve a stable voltage.

All you need is a DC-DC CC/CV charging circuit, with finetuning V and A option.
I showed in previous posts what kind of converter I use. Simple $4 converters.
One needed for every voltage needed.

Of course, CC/CV charger has LDO on board.....


Just charge the ultracap with preset voltage of CC/CV converter.

@Ian

Not sure if you want to incorporate a CC/CV charger on board, would be nice, but not neccessary though.
You could design a pcb with microcontroller controlled voltage sensing circuit with input terminals leading to CC/CV charger, and terminals for connecting the ultracaps, and of course terminals for output voltage.

Another thing not to forget:

The PCB needs a ON/OFF switch option which disconnects ALL ultracaps from output. In my case this was not possible, thus, each time when starting up dac i had down-time because ultracaps were drained, or at least one bank, and possibly the other for lets say 95%, depending on the time when switched off.
The problem was, when switching once in 30 minutes, I had to wait at least 30 minutes before switching to charged bank.....
That is something to keep in mind when designing!

Cheers guys!
Alex
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Last edited by Abartels1965; 15th June 2018 at 12:59 PM.
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Old 15th June 2018, 02:30 PM   #440
iancanada is offline iancanada  Canada
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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
Quote:
Originally Posted by Abartels1965 View Post
All you need is a DC-DC CC/CV charging circuit, with finetuning V and A option.
I showed in previous posts what kind of converter I use. Simple $4 converters.
One needed for every voltage needed.

Of course, CC/CV charger has LDO on board.....


Just charge the ultracap with preset voltage of CC/CV converter.

@Ian

Not sure if you want to incorporate a CC/CV charger on board, would be nice, but not neccessary though.
You could design a pcb with microcontroller controlled voltage sensing circuit with input terminals leading to CC/CV charger, and terminals for connecting the ultracaps, and of course terminals for output voltage.

Another thing not to forget:

The PCB needs a ON/OFF switch option which disconnects ALL ultracaps from output. In my case this was not possible, thus, each time when starting up dac i had down-time because ultracaps were drained, or at least one bank, and possibly the other for lets say 95%, depending on the time when switched off.
The problem was, when switching once in 30 minutes, I had to wait at least 30 minutes before switching to charged bank.....
That is something to keep in mind when designing!

Cheers guys!
Alex
I think what you need is a micro processor based ultracapacitor PSU controller with isolated voltage sensing and isolated ON/OFF control signal.

Have to have a display to show the status, also some consideration of protecting relays from damaging by the inrush current...


Regards,
Ian
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