[jarpatus]

Quote:

Originally Posted by rjkdivin /img/forum/go_quote.gif Kranious, Regulated 5v wallwarts with the small tip are hard to find. I used the Jameco 164101 retipped with the Jameco 71192 plug.....if you do this, pay close attention to the polarity. The 164101 is a 500mW unit.

Why not to power it thorugh USB? Even if you will not use this anyway near computers, you probably could buy some kind of USB charger with little money? Ok, those PSU's are probably switching rather than linear, but does it actually matter?

At least in europe all major cellular phone manufacturers did agree on standard data+charger connector which they will be using for their new phones. Connector is Micro-USB. Is this true in US (and Asia and...) to? Because then one could use Micro-USB connector in gamma instead of original Mini-USB (are connectors pin & dimensions compatible?) and have no problem finding stand alone charger.

Ps. Oh why they had to choose micro-USB instead of mini? I mean, I have dozens of mini-USB cables, but none micro...

 

[m1abrams]

Quote:

Originally Posted by jarpatus /img/forum/go_quote.gif Why not to power it thorugh USB? Even if you will not use this anyway near computers, you probably could buy some kind of USB charger with little money? Ok, those PSU's are probably switching rather than linear, but does it actually matter? At least in europe all major cellular phone manufacturers did agree on standard data+charger connector which they will be using for their new phones. Connector is Micro-USB. Is this true in US (and Asia and...) to? Because then one could use Micro-USB connector in gamma instead of original Mini-USB (are connectors pin & dimensions compatible?) and have no problem finding stand alone charger. Ps. Oh why they had to choose micro-USB instead of mini? I mean, I have dozens of mini-USB cables, but none micro...

Because the mini was deprecated.

 

[Horio]

I'm wanting to build the σ25/σ24 to power the y2 (to perhaps enclose with a CKK3 or M^3), and I'm having a heck of a time finding the proper transformer for the (AMB recommends a 2.8VA with 9V secondary). Mouser and Digikey don't seem to stock these. Mouser stocks a 2.3VA but I'm not sure that will cut it. This is my first time doing a DIY power supply, so I'm a bit of a newb. Any advice or suggested alternatives is greatly appreciated.

 

[m1abrams]

Quote:

Originally Posted by Horio /img/forum/go_quote.gif I'm wanting to build the σ25/σ24 to power the y2 (to perhaps enclose with a CKK3 or M^3), and I'm having a heck of a time finding the proper transformer for the (AMB recommends a 2.8VA with 9V secondary). Mouser and Digikey don't seem to stock these. Mouser stocks a 2.3VA but I'm not sure that will cut it. This is my first time doing a DIY power supply, so I'm a bit of a newb. Any advice or suggested alternatives is greatly appreciated.

Digi-Key - 567-1040-5-ND (Manufacturer - BV030-7597.0)

 

[Horio]

I saw that too, but I was hoping for something with a ship date earlier than April 13th.

Maybe I'll just have to bite the bullet.

Quote:

Originally Posted by m1abrams /img/forum/go_quote.gif Digi-Key - 567-1040-5-ND (Manufacturer - BV030-7597.0)

 

[jarpatus]

Quote:

Originally Posted by m1abrams /img/forum/go_quote.gif Because the mini was deprecated.

Checked the wikipedia and you are correct, it was deprecated in 2007. So why do I still have mini connectors in every single device I have bought after 2007... Oh well, industry is slow to change.

Amb, did you know, you are using deprecated connector in gamma-1

Edit: Corrected micro -> mini

 

[amb]

Many Motorola, Blackberry (and others) cell phones use Mini-USB connectors for charging as well as for data. So a charger for such phones could be used, but they are usually switch-mode rather than linear, and could be rather noisy.

 

[kranius]

well I think I'm gonna stick to sigma 11

overkill sounds nice to me eh

 

[K3cT]

Quote:

Originally Posted by Horio /img/forum/go_quote.gif I'm wanting to build the σ25/σ24 to power the y2 (to perhaps enclose with a CKK3 or M^3), and I'm having a heck of a time finding the proper transformer for the (AMB recommends a 2.8VA with 9V secondary). Mouser and Digikey don't seem to stock these. Mouser stocks a 2.3VA but I'm not sure that will cut it. This is my first time doing a DIY power supply, so I'm a bit of a newb. Any advice or suggested alternatives is greatly appreciated.

You can use a normal toroidal transformer and skip the σ24.

 

[thoppa]

Hi,

I'm going to make a σ11 for the y2 to use as a desktop dac because it is the lowest noise psu I know of, and I'm sure the op amp will perform better with sweeter juice. The op amp only has the minimum decoupling so I don't agree that the σ11 is a 'waste'. I've also read that switching noise can increase jitter.

I'm also using a y2 as a portable dac, running off usb power. I am thinking about how to clean up the usb power at the input using a pi filter or something similar, in addition to the onboard ferrites. I got a couple of chokes (100uH and 140uH) and I'm wondering what cap to put between them, or just use one and put a cap each side. Does anyone have any experience with doing this kind of power filter ?

I think I want to have a pole frequency of around 30Khz, so with a 140uH coil, I'll need two .22uF....will this work ?
F = 1 / (6.3*((LC)^0.5))

Thanks,

Tom

 

[linuxworks]

tom, why do you assume you need to 'preclean' the y1/y2 ?

the onboard regs are the limiting factor; so a 7805 or 317 is 'all you need'.

s11 is fine. very very low noise. but its so low, its lower than the onboard regs. you are 'wasting' it, in a way. s11 puts out a lot of heat. I consider that wasteful since 90% (WAG) of it goes unused.

if you really want to 'upgrade' the PSU, then swap out the onboards and find some lower noise solution for those. THAT would be an effective upgrade. but playing around 'before' the y2 seems mostly pointless to me.

 

[ShinyFalcon]

Since you're playing with "desktop size," how about bypassing the 4.5V analog regulator with the σ11 (and at the same time having the σ11 power the 3.3V regulators)? Will you have two y2's to play with? If it's just one this idea may be difficult to implement but possible.

666th

 

[thoppa]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif tom, why do you assume you need to 'preclean' the y1/y2 ? the onboard regs are the limiting factor; so a 7805 or 317 is 'all you need'. s11 is fine. very very low noise. but its so low, its lower than the onboard regs. you are 'wasting' it, in a way. s11 puts out a lot of heat. I consider that wasteful since 90% (WAG) of it goes unused. if you really want to 'upgrade' the PSU, then swap out the onboards and find some lower noise solution for those. THAT would be an effective upgrade. but playing around 'before' the y2 seems mostly pointless to me.

Hi,

I've seen on a scope that regulators perform well at low frequencies but not so good at high frequency, so they don't do much to remove the original switching noise. Hence the 'need' for a filter for the usb-powered y2. The board uses quite a few ferrites already to filter noise, but I'd like to do 'more'.

I didn't even think about the onboard regs for the desktop y2 - I'll definitely look into bypassing or replacing them. Thanks for that !

I still don't see the waste - this dac uses puny amounts of current so the psu will only need small heatsinks - it'll only be burning off 1 watt or so. If you mean efficiency, well, yeah, it'll be less than 50% .....

Tom

 

[thoppa]

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif Since you're playing with "desktop size," how about bypassing the 4.5V analog regulator with the σ11 (and at the same time having the σ11 power the 3.3V regulators)? Will you have two y2's to play with? If it's just one this idea may be difficult to implement but possible. 666th

yes, very good point. I can set the psu to 4.75V (what is the maximum / minumum voltage ? )and replace the 3.3V regs with lower noise ones.

I intend to use a 5V 1ppm xo so I'll find out what the voltage requirements are for that too. Of course, I'll need to re-route power cos the xo uses 3.3V in the design.

 

[amb]

σ11's output voltage should not be set lower than 5V. Otherwise the devices will get too close to the edge of their linear region and the PSU would fall out of regulation. OTOH, the "4.5V" analog supply can be 5V so you could use σ11 to drive it directly.

The LP2985AIM5-3.3 regulator's noise spec is ~30µV, 300Hz-50KHz. The TPS79333DBVR is ~35µV, 200Hz-100KHz. While these are not nearly as quiet as a σ11 at 5V, they are pretty good by any standard.

The LP2985's ripple rejection is rated 40-something dB at 1KHz (no other frequencies listed) whereas TPS79333's ripple rejection is much better at ~70dB in the audio band, dropping to the 40-something dB range at 100KHz.

Given this, there should be some benefit to using a σ11 upstream of the 3.3V regulators to form a two-stage regulator. The 3.3V regulators will add a very small amount of noise, but the σ11 should help filter out much of the USB power noise.

My own testing of USB-power vs. σ25 external PSU on both γ1 and γ2 showed a measurable reduction in noise floor "hash". My computer's USB power is relatively clean, and I can't hear any of the noise even though I see it in the spectrum analyzer. FWIW, a few people have reported hearing noise with certain computers, and cured it by changing to either σ25 or σ11 external power.