Yes, the physical/thermal stress wear and tear depends on the device
response relative to the ripple frequency. TECs aren't the only things
with these issues - even modern high power LEDs used for illumination
are known to last longest when run from "pure" DC, for a given average
power level.
Hi
Depends very much on what sort of environment it’s in ….
Bob
> On Dec 21, 2020, at 9:03 PM, Dana Whitlow wrote:
>
> A properly-tuned PID system does not cycle!
>
> Dana
>
>
> On Mon, Dec 21, 2020 at 6:49 PM Bob kb8tq wrote:
>
>> Hi
>>
>> Finding a data sheet on a TEC that goes past *v
On 12/21/20 5:59 PM, Gerhard Hoffmann wrote:
Both agree that ripple > 1 KHz is harmless. But then the current
delivered
to the TEC is quite large usually - and It's a different question if
you want such
large and dirty currents on your table or in your device.
Yes.. we were testing a sens
A properly-tuned PID system does not cycle!
Dana
On Mon, Dec 21, 2020 at 6:49 PM Bob kb8tq wrote:
> Hi
>
> Finding a data sheet on a TEC that goes past *very* basic stuff is
> essentially
> impossible. The bottom line is that the people who make them very much
> want to sell them to you. Findi
Am 22.12.20 um 00:43 schrieb Hal Murray:
[Old mail, context is TECs] bruce.griffi...@xtra.co.nz said:
If the drive current ripple is too high fatigue failure from cyclic
thermomechanical stress can be significant.
Do good data sheets say anything about that? Is there a frequency term
in there
Original source about TEC lifetime reduction when the TEC ripple cureent is
high:
https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1991-02.pdf
Page 74
I suspect that someone there may have been bitten by the short TEC life
experienced without the LC filter.
Although they used relatively small TEC
Hi
Finding a data sheet on a TEC that goes past *very* basic stuff is essentially
impossible. The bottom line is that the people who make them very much
want to sell them to you. Finding information in those data sheets that suggest
problems … not so much.
The problem is (mainly) physical. The
[Old mail, context is TECs]
bruce.griffi...@xtra.co.nz said:
> If the drive current ripple is too high fatigue failure from cyclic
> thermomechanical stress can be significant.
Do good data sheets say anything about that?
Is there a frequency term in there? Can I use PWM, which is as much ripp
On Monday, November 23, 2020 7:33:49 AM EST 李 wrote:
> When the Rb clock is working, it needs a high temperature, isn't heat
> dissipation breaking the heat balance?Increased power consumption？
It needs a *stable* temperature. It has a heater to provide regulation. The
thing about a heater for st
Hi
The physics package is not really that different than an OCXO. It needs to hit
this or that temperature. You
derate the parts that go into the “hot zone” in order to hit a “reasonable"
MTBF. Indeed, some manufacturers
seem to do a better job in this regard than others.
The parts on the re
I see, I've always wondered if the internal electronics are specially made
because the modules are really too hot.
Assuming a temperature increase of 10 degrees and the operating life is reduced
by half, the module life should not be long.
| |
李
|
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邮箱bd...@126.com
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签名由 网易邮箱大师 定制
On 11/23/20
Hi
There are two “zones” in the typical Rb physics package. They both need to be
heated. Unfortunately they need
to be heated to *different* temperatures. This makes for an interesting design.
Insulate things to well and the one
that is supposed to be at a slightly lower temperature is heated up
When the Rb clock is working, it needs a high temperature, isn't heat
dissipation breaking the heat balance?Increased power consumption？
| |
李
|
|
邮箱bd...@126.com
|
签名由 网易邮箱大师 定制
On 10/23/2020 20:56, Bob kb8tq wrote:
Hi
I must admit, the longevity of the compressor based setup in the typic
From: ed breya <mailto:e...@telight.com>
To: mailto:time-nuts@lists.febo.com
Subject: Re: [time-nuts] SMPS or conventional?
"Regarding TEC life, ..."
A really good reference to TECs, especially factors affecting lifetime is here -
https://tetech
Bob kb8tq writes:
> I must admit, the longevity of the compressor based setup in the typical
> kitchen
> fridge continues to amaze me. :).
Thank Mads Clausen for that:
https://www.secop.com/fileadmin/user_upload/files/danfoss_compressor_business_book_english.pdf
--
Poul-H
Hi
I must admit, the longevity of the compressor based setup in the typical
kitchen
fridge continues to amaze me. :).
===
TEC’s have a fairly limited “pumping range”. It is not uncommon to discover you
need to stack them to get this or that job done. We wound up with a stack of
5 to get o
> TEC’s are indeed prone to wear out. That said, so is a compressor …..
The mechanism is almost entirely mechanical and running a TEC at a
stable current almost 100% mitigates it.
The surefire way to force the wearout is to reverse the current
direction a lot.
Whatever you use to contr
I suspect that one of the main issues these days is the quality of
the module - there is a lot of unbranded stuff out there of unknown
quality.
Cooling a rubidium is probably a relatively easy life for a peltier
since there are limited temperature changes, but I would still make
sure that I h
If the drive current ripple is too high fatigue failure from cyclic
thermomechanical stress can be significant.
Bruce
> On 23 October 2020 at 10:37 ed breya wrote:
>
>
> Regarding TEC life, in my experience, what wrecks them the most is
> cooling applications where the cold side is below the
Regarding TEC life, in my experience, what wrecks them the most is
cooling applications where the cold side is below the dew point, and
water condenses out onto and into the TEC Peltier array. This eventually
rots the elements from corrosion and electrolysis, until something craps
out. If the T
Hi
The magnetic field sensitivity is dependent on a lot of things.
Strangely enough, the higher the C field, the more sensitive
the physics package is ( yes, that’s weird …). All Rb’s incorporate
shielding to reduce the external field impact. Since the shielding
is rarely perfect, there are asym
Hi
TEC’s are indeed prone to wear out. That said, so is a compressor …..
Bob
> On Oct 22, 2020, at 12:36 AM, Hal Murray wrote:
>
>> like with TEC heat/cool capability
>
> What's the typical MTBF of TEC coolers? How much does it depend on how much
> power you put through them?
>
> --
> The
Hi,
The magnetic field issue has bothered me a little too, but I don't
know whether it has a practical effect. Maybe putting a fan in a
plastic or aluminium box close to the Rb might show something - unless
someone already knows the effects.
I have a compass on the bench beside the LPRO, an
> like with TEC heat/cool capability
What's the typical MTBF of TEC coolers? How much does it depend on how much
power you put through them?
--
These are my opinions. I hate spam.
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubsc
Regarding linear versus SMPS, I always prefer linear where possible. As
others have said, for assessing a SMPS, try it and see. If it does the
job sufficiently without too much noise, then go with it.
Regarding Rb cooling, I don't know about the newer, smaller ones - I
only have three big old
Hello Time-Nuts,
Though this thread started out asking about power supplies, it seems
to have morphed into a Rb cooling discussion as well.
I undertook a similar PRS-10 project a while back. Since the PRS-10
uses an SC cut crystal and has decent phase noise for a small rubidium
I went the linear
Hi
The only issue with the “controlled fan” approach is that you
have a variable magnetic field as a result. That and the vibration
both can impact the stability of the Rb. Some means of isolating
the fan from the immediate vicinity of the Rb sounds like a good idea.
Bob
> On Oct 21, 2020, at 9
Hi
> On Oct 21, 2020, at 8:40 AM, Wannes Sels wrote:
>
> There are conflicting requirements regarding temperature in Rb's:
>
> - For best performance, the rubidium and quartz oscillators must be kept at
> a high and stable temperature.
> - For reliability, the supporting electronics must be kep
Hi
The devices all *worked* just fine, even without any heatsink
at all. There was no performance impact to the (lack of) heatsink
in a normal lab environment.
Small in this case is mounting the device to a heatsink that is the
size of the “hot” side and maybe a half inch of fins. Fins always g
I am thinking in an black aluminium finned heatsink, the size of the
base plate, and a fan, controlled by an electronic thermostat (sensor
direct coupled to the heatsink). Is that ok?
Em 21/10/2020 09:40, Wannes Sels escreveu:
There are conflicting requirements regarding temperature in Rb's:
I prefer the use of non-switching power supplies, in part because I am
forced to use
indoor receiving antennas not very far from my equipment setup. However,
one of my
Rb standards, an used L-Pro which I bought from another ham, came with a
SMPS
and I've never noted any particular problem. So, my
> Planning to build my "reference box" with a rubidium & a gpsdo.
I went through this power supply decision making process with my first
OCXO and Rb standards. In the end my conclusions are "if you can't
measure it then don't worry about it". You can see how that leads to a
side hobby of noise
IN the Datum User’s Guide for the LPRO there is a set of data for MTBF.
Ambient TemperatureMTBF Hours
20 381000
25 351000
30 32
40 253000
50 189000
60 134000
This sh
There are conflicting requirements regarding temperature in Rb's:
- For best performance, the rubidium and quartz oscillators must be kept at
a high and stable temperature.
- For reliability, the supporting electronics must be kept at a lower
temperature.
The heater takes care of the high tempera
> I spent a lot of years buying Rbâs and putting them on small heatsinks. I
> always was disappointed in their reliability. That continued to be the case
> up to the point that the baseplate tempâs got into the 40C region. In my
> case, that took a fan â¦.
How well did it work if the heat
Hi
I spent a lot of years buying Rb’s and putting them on small heatsinks.
I always was disappointed in their reliability. That continued to be the
case up to the point that the baseplate temp’s got into the 40C region.
In my case, that took a fan ….
Bob
> On Oct 20, 2020, at 7:32 PM, Bill Not
Hi Bob
In a previous tread, someone said that cooling PRS-10 will only make the
unit consume more energy, since it has to maintain the lamp hot.
Is this wrong?
Before I read the previous tread, I was thinking of electronic
thermostat/fan but...
Em 20/10/2020 10:34, Bob kb8tq escreveu:
Hi
N
Hi
> On Oct 20, 2020, at 10:45 AM, Luiz Alberto Saba wrote:
>
> Hi Bob
>
> In a previous tread, someone said that cooling PRS-10 will only make the unit
> consume more energy, since it has to maintain the lamp hot.
> Is this wrong?
You need to read the entire thread. Cooling a Telecom Rb to a
Hi
What will the output of the box be used for? If low phase noise is an objective,
then one needs to be pretty careful about power supply noise. If low phase noise
is not a “need” in this case, then (good) switchers can be used for everything.
What’s a “good” switcher? You want one that is reli
Hi guys
Planning to build my "reference box" with a rubidium & a gpsdo.
SMPS will do a good job or the transformer+bridge+capacitor+regulator is
best suited for this application?
In the "test phase" I've used a switched ps for the rubidium and a
conventional for the gpsdo.
Thanks
Luiz Albert
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