Anybody want a Thunderbolt power supply?
Yes, at times I used a two stage linear regulator. The first stage had excellent low freq rejection and the final stage too care of the high freq stuff.
Some times a full linear supply is not a viable option due to power dissipation/size issues or the utter convenience of using a switching wall wart.
Precisely the reason to avoid switchers entirely and use linear-only
voltage regulators to power noise-sensitive circuits. As I mentioned
before, I had to use two stages of well-designed linear regulation to
make any switching supply acceptable (at a time-nuts level) for use with
a Tbolt.
I'm being Devil's Advocate here because I certainly realise switchers do
generate high frequency noise. But wasn't the intention of them to make
filtering easier, with smaller filter components, exactly because they
operate at higher frequencies ?
So why do they fail ? Is it cost-cutting to make them only just good enough
for typical uses ? Shouldn't it be possible to make the best possible
supply from a switcher, if only cost and weight weren't the first
considerations ?
On Wed, Aug 31, 2016 at 9:45 PM, Mark Sims holrum@hotmail.com wrote:
Yes, at times I used a two stage linear regulator. The first stage had
excellent low freq rejection and the final stage too care of the high freq
stuff.
Some times a full linear supply is not a viable option due to power
dissipation/size issues or the utter convenience of using a switching wall
wart.
Precisely the reason to avoid switchers entirely and use linear-only
voltage regulators to power noise-sensitive circuits. As I mentioned
before, I had to use two stages of well-designed linear regulation to
make any switching supply acceptable (at a time-nuts level) for use with
a Tbolt.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
On 8/31/16 1:52 PM, Adrian Godwin wrote:
I'm being Devil's Advocate here because I certainly realise switchers do
generate high frequency noise. But wasn't the intention of them to make
filtering easier, with smaller filter components, exactly because they
operate at higher frequencies ?
So why do they fail ? Is it cost-cutting to make them only just good enough
for typical uses ? Shouldn't it be possible to make the best possible
supply from a switcher, if only cost and weight weren't the first
considerations ?
Sure.. you can do a bunch of LC low pass sections and knock it down, but
building a wideband low pass filter with good ultimate rejection is
also challenging.
In a system I'm actually sitting next to, we have a switcher followed by
a 60dB rejection lumped LC followed by the power distribution, followed
by a 60 dB rejection lumped LC followed by a linear regulator.
When you're at this kind of level, layout and mechanical arrangement is
important, because the switching noise (which is also on the input) can
couple "around" your other circuits.
The other challenge is that those filters have resistive loss - if you
want good regulation, how do you get your "sense" voltage back to the
regulator without that path being the path for the noise - so you'd need
to put LP filters on the sense line.
And of course, the L's need to be shielded.
And you put it in nesting boxes made of steel
A linear regulator is a LOT easier.
If you aren't power dissipation constrained, then it's often the easiest
way to get to where you want to be.
Mark wrote:
Some times a full linear supply is not a viable option due to power dissipation/size issues or the utter convenience of using a switching wall wart.
In the context of the present discussion -- powering a Tbolt for
time-nuts use -- the first consideration would just be laughable and the
second would be nothing but terminal laziness.
Best regards,
Charles
OTOH, how many time-nuts have any interest in paying for a power supply that's up to time-nuts standards? It's really not easy to bring a small product to market at a small price. Even if you completely discount the personal effort of design, construction, and marketing, there's the issue of packaging. Without a package, it's just an amateur effort not worth considering. With a package, such as a Hammond box, the price moves into new territory and nobody's interested.
Bob
From: Charles Steinmetz <csteinmetz@yandex.com>
To: time-nuts@febo.com
Sent: Wednesday, August 31, 2016 4:24 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply?
Mark wrote:
Some times a full linear supply is not a viable option due to power dissipation/size issues or the utter convenience of using a switching wall wart.
In the context of the present discussion -- powering a Tbolt for
time-nuts use -- the first consideration would just be laughable and the
second would be nothing but terminal laziness.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Bob wrote:
OTOH, how many time-nuts have any interest in paying for a power supply that's up to time-nuts standards? It's really not easy to bring a small product to market at a small price. Even if you completely discount the personal effort of design, construction, and marketing, there's the issue of packaging. Without a package, it's just an amateur effort not worth considering. With a package, such as a Hammond box, the price moves into new territory and nobody's interested.
So the answer is to bring crap to market because nobody will pay for
something that actually does the job?
IMO, the answer is to accept that the small, "little gizmo" providers
simply cannot fulfill this need efficiently. I provided one solution,
using a surplus device from a large supplier and fifteen minutes of
soldering-iron time. Even if you buy a box for it, it won't cost much
more than the $25 the OP proposed (and maybe not as much -- the ones
I've made have cost less than $25 each). (And note that the OP did not
propose a complete, mains-to-Tbolt solution. The proposed solution
assumed an existing mains-to-12v supply.)
That is part (the essential part, IMO) of the "little gizmo" provider's
business model -- find niche markets where things made at that scale
provide better performance than the alternatives. There are lots of
areas where this can be done, but also very many more where it cannot.
The "little gizmo" provider is well-advised to learn how to tell the one
from the other.
Best regards,
Charles
Charles,
said: "So the answer is to bring crap to market because nobody will pay for something that actually does the job?"
I don't mean to cause offense, but is everything you don't like crap? The reality is that whatever the market will bear is what determines what comes to market. If you can find high quality goods on ebay that can be modified to fit your needs, then you win. There is a substantial market that either cannot do those mods or would rather spend their time elsewhere. So, what they're willing to pay is going to determine what's available for sale.
As an example, my cost for the Hammond box I use with my GPSDO, with finished end panels, is just under $60. From that viewpoint, I shouldn't bother to make it, because a surplus unit can always be found for a cheaper price, as long as I'm willing to accept whatever unknown baggage (no schematics, unobtainium parts, no software, etc) comes with that surplus unit.
Bob
-----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Charles Steinmetz <csteinmetz@yandex.com>
To: time-nuts@febo.com
Sent: Wednesday, August 31, 2016 5:02 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply?
Bob wrote:
OTOH, how many time-nuts have any interest in paying for a power supply that's up to time-nuts standards? It's really not easy to bring a small product to market at a small price. Even if you completely discount the personal effort of design, construction, and marketing, there's the issue of packaging. Without a package, it's just an amateur effort not worth considering. With a package, such as a Hammond box, the price moves into new territory and nobody's interested.
So the answer is to bring crap to market because nobody will pay for
something that actually does the job?
IMO, the answer is to accept that the small, "little gizmo" providers
simply cannot fulfill this need efficiently. I provided one solution,
using a surplus device from a large supplier and fifteen minutes of
soldering-iron time. Even if you buy a box for it, it won't cost much
more than the $25 the OP proposed (and maybe not as much -- the ones
I've made have cost less than $25 each). (And note that the OP did not
propose a complete, mains-to-Tbolt solution. The proposed solution
assumed an existing mains-to-12v supply.)
That is part (the essential part, IMO) of the "little gizmo" provider's
business model -- find niche markets where things made at that scale
provide better performance than the alternatives. There are lots of
areas where this can be done, but also very many more where it cannot.
The "little gizmo" provider is well-advised to learn how to tell the one
from the other.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi
The fact is that commercial linear supplies are still out there for pretty cheap prices. The price of a usable switcher is a very small fraction of the price of a Tbolt. Noise on the switcher is a big deal. Not everybody seems to care about low phase noise on the 10 MHz. Switcher frequency supply noise has very little impact on the PPS output.
Bob
On Aug 31, 2016, at 5:29 PM, Bob Stewart bob@evoria.net wrote:
OTOH, how many time-nuts have any interest in paying for a power supply that's up to time-nuts standards? It's really not easy to bring a small product to market at a small price. Even if you completely discount the personal effort of design, construction, and marketing, there's the issue of packaging. Without a package, it's just an amateur effort not worth considering. With a package, such as a Hammond box, the price moves into new territory and nobody's interested.
Bob
From: Charles Steinmetz <csteinmetz@yandex.com>
To: time-nuts@febo.com
Sent: Wednesday, August 31, 2016 4:24 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply?
Mark wrote:
Some times a full linear supply is not a viable option due to power dissipation/size issues or the utter convenience of using a switching wall wart.
In the context of the present discussion -- powering a Tbolt for
time-nuts use -- the first consideration would just be laughable and the
second would be nothing but terminal laziness.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Wow, given all the responses about the cleanliness of the power into a Thunderbolt, I would be even more interested in a power supply that did not leave the "last mile" up to me. I would be more interested in a "pretty clean" power supply that I could just plug in and go. Any thoughts of me actually wiring the last bit of it make me break out in a cold sweat and come face to face with my (established, and sadly slow-to-expand) limitations.
Maybe I'm the only one that would be interested in such a solution? I hope not, but I can see that there is a lot to consider about such a thing.
Cheers!
-Randal
(at CubeCentral)
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Bob Stewart
Sent: Wednesday, 31 August, 2016 15:29
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply?
OTOH, how many time-nuts have any interest in paying for a power supply that's up to time-nuts standards? It's really not easy to bring a small product to market at a small price. Even if you completely discount the personal effort of design, construction, and marketing, there's the issue of packaging. Without a package, it's just an amateur effort not worth considering. With a package, such as a Hammond box, the price moves into new territory and nobody's interested.
Bob
From: Charles Steinmetz <csteinmetz@yandex.com>
To: time-nuts@febo.com
Sent: Wednesday, August 31, 2016 4:24 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply?
Mark wrote:
Some times a full linear supply is not a viable option due to power dissipation/size issues or the utter convenience of using a switching wall wart.
In the context of the present discussion -- powering a Tbolt for time-nuts use -- the first consideration would just be laughable and the second would be nothing but terminal laziness.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
there are peoples and societies for whom the most important parameter is
the price of the goods, and there are also some societies for them the
most important is the proffit
73
Alex
On 8/31/2016 3:13 PM, Bob Stewart wrote:
Charles,
said: "So the answer is to bring crap to market because nobody will pay for something that actually does the job?"
I don't mean to cause offense, but is everything you don't like crap? The reality is that whatever the market will bear is what determines what comes to market. If you can find high quality goods on ebay that can be modified to fit your needs, then you win. There is a substantial market that either cannot do those mods or would rather spend their time elsewhere. So, what they're willing to pay is going to determine what's available for sale.
As an example, my cost for the Hammond box I use with my GPSDO, with finished end panels, is just under $60. From that viewpoint, I shouldn't bother to make it, because a surplus unit can always be found for a cheaper price, as long as I'm willing to accept whatever unknown baggage (no schematics, unobtainium parts, no software, etc) comes with that surplus unit.
Bob
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Charles Steinmetz <csteinmetz@yandex.com>
To: time-nuts@febo.com
Sent: Wednesday, August 31, 2016 5:02 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply?
Bob wrote:
OTOH, how many time-nuts have any interest in paying for a power supply that's up to time-nuts standards? It's really not easy to bring a small product to market at a small price. Even if you completely discount the personal effort of design, construction, and marketing, there's the issue of packaging. Without a package, it's just an amateur effort not worth considering. With a package, such as a Hammond box, the price moves into new territory and nobody's interested.
So the answer is to bring crap to market because nobody will pay for
something that actually does the job?
IMO, the answer is to accept that the small, "little gizmo" providers
simply cannot fulfill this need efficiently. I provided one solution,
using a surplus device from a large supplier and fifteen minutes of
soldering-iron time. Even if you buy a box for it, it won't cost much
more than the $25 the OP proposed (and maybe not as much -- the ones
I've made have cost less than $25 each). (And note that the OP did not
propose a complete, mains-to-Tbolt solution. The proposed solution
assumed an existing mains-to-12v supply.)
That is part (the essential part, IMO) of the "little gizmo" provider's
business model -- find niche markets where things made at that scale
provide better performance than the alternatives. There are lots of
areas where this can be done, but also very many more where it cannot.
The "little gizmo" provider is well-advised to learn how to tell the one
from the other.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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