Re: [time-nuts] How did they distribute time in the old days?

[Tim Shoppa]

As recently as 1987, there was poor to no absolute time synchronization at
the world's underground neutrino detectors. When light and neutrino fronts
from supernova SN1987A arrived, the best they were able to put absolute
timestamps on neutrino events was about 1 minute.

Even after the neutrino arrivals they may have been able to back-correct
timestamps on the Kamiokande data to within milliseconds, but a power
failure a few days after SN1987A detection prevented this.

The timescales that the Kamiokande and IMB neutrino detectors were
originally designed to measure? Circa 10 to the 31st years!

Today the realtime neutrino detectors are tied together into a network to
look for neutrino bursts in realtime, and even determine direction to point
optical telescopes. The neutrino burst for a SN1987A type event precedes
the optical detectability by a few hours.

Tim N3QE

On Wednesday, October 14, 2015, Hal Murray  wrote:

>
> hol...@hotmail.com said:
> > Somewhat time-nut related...  the project main application needed
> > millisecond consistent (not necessarily accurate) time stamps on a
> > world-wide network.  That was in the pre-gps, pre-fiber, pre-historic
> > before-times.  I don't think that they ever quite got there.
>
> World wide seismology took off in the early 1970s as background for nuclear
> underground non-testing treaties.  Both the US and the USSR had to be sure
> they could detect the opponents tests and distinguish tests from
> earthquakes.
>  We had seismic stations scattered around the globe.
>
> Does anybody know how they distributed time back then and/or how accurately
> they could do it?
>
> Google says the speed of sound in rock is 6-8 km/s so 10 ms error would be
> 100 meters.  That seems like a reasonable ballpark.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] How did they distribute time in the old days?

[Alan Melia]

Well I dont know if it was used for that but the16kHz VLF station at Rugby 
call-sign GBR was rebuilt in 1967 and the output tank circuit stiffened to 
provide better phase stability specifically foe international time standard 
comparison. The transmitter was used for initial comparisons between NPL and 
NBS (later NIST) time standards. It was also the starting point for the 
Omega nav system. Prior to that accurate time data was passed over twisted 
pairs in UK and probably Europe.


Alan
G3NYK
- Original Message - 
From: "Hal Murray" 
To: "Discussion of precise time and frequency measurement" 


Cc: 
Sent: Wednesday, October 14, 2015 6:12 AM
Subject: [time-nuts] How did they distribute time in the old days?




hol...@hotmail.com said:

Somewhat time-nut related...  the project main application needed
millisecond consistent (not necessarily accurate) time stamps on a
world-wide network.  That was in the pre-gps, pre-fiber, pre-historic
before-times.  I don't think that they ever quite got there.


World wide seismology took off in the early 1970s as background for 
nuclear

underground non-testing treaties.  Both the US and the USSR had to be sure
they could detect the opponents tests and distinguish tests from 
earthquakes.

We had seismic stations scattered around the globe.

Does anybody know how they distributed time back then and/or how 
accurately

they could do it?

Google says the speed of sound in rock is 6-8 km/s so 10 ms error would be
100 meters.  That seems like a reasonable ballpark.



--
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Re: [time-nuts] UPS for my time rack

[Dave Martindale]

How did you find the units that will act as a UPS, without buying
everything on the market and testing them?

I just checked all of those bricks in our house, and none will do it.
There are a couple of PNY units that do not provide output power until a
button is pressed, and don't charge until input power is connected while in
idle mode.  Then there are Tp-Link and Mophie units that switch on the
output automatically when a load is connected (or perhaps the output is
just always powered), but which disable the output and switch to charge
mode when input power is provided.  None of them seem able to pass through
5V power without discharging.

- Dave

On Tue, Oct 13, 2015 at 2:07 PM, Tom Van Baak  wrote:

>
> Recently, as some of my gear works from 5 VDC, those ~2600 mAh mobile
> phone USB backup power bricks make an excellent mini-UPS. The ideal models
> are those without LEDs or on/off buttons so they discharge and charge/float
> seamlessly without manual intervention, even if fully drained.
>
> Multiple units can be placed in series for additional, if slightly
> inefficient, capacity. A good self-test is:
>
> http://leapsecond.com/images/perpetual-USB-power.jpg
>
> /tvb
>
>
>
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Re: [time-nuts] UPS for my time rack

[Poul-Henning Kamp]

In message <20151013225202.1e70a...@aluminium.mobile.teply.info>, Florian Teply
 writes:

>DC-DC converters with very
>good efficiency exist for quite some time now.

The one I just put in my HP5065A does 60W with 90+% efficiency
in a 2x1x.5 inch package:

http://phk.freebsd.dk/hacks/HP5065A/20150930_dcdc/index.html

>Umm, around here, at least for ham radio operators, it seems many
>standardize now on PowerPole connectors for 12V DC.

They're quite neat, but I wish there were something a little less
heavy-duty for the 1-2 Amp range.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] How did they distribute time in the old days?

[Howard Davidson]

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1964-07.pdf


On 10/13/2015 10:12 PM, Hal Murray wrote:

hol...@hotmail.com said:

Somewhat time-nut related...  the project main application needed
millisecond consistent (not necessarily accurate) time stamps on a
world-wide network.  That was in the pre-gps, pre-fiber, pre-historic
before-times.  I don't think that they ever quite got there.

World wide seismology took off in the early 1970s as background for nuclear
underground non-testing treaties.  Both the US and the USSR had to be sure
they could detect the opponents tests and distinguish tests from earthquakes.
  We had seismic stations scattered around the globe.

Does anybody know how they distributed time back then and/or how accurately
they could do it?

Google says the speed of sound in rock is 6-8 km/s so 10 ms error would be
100 meters.  That seems like a reasonable ballpark.





--
Howard L. Davidson
hl...@att.net

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Re: [time-nuts] How did they distribute time in the old days?

[Will]

Hi,

They used  (late 1970's) WWV or WWVH to sync up the time.  There was
fancy system that used a neon on a rotating disc rather like an early
depth sounder. Neon flashed with seconds beep. There was a way of
rotating the field that drove the disk to advance/delay the system to
set it fairly accurately.

Cheers,
Will

On 14/10/15 18:12, Hal Murray wrote:
> hol...@hotmail.com said:
>> Somewhat time-nut related...  the project main application needed
>> millisecond consistent (not necessarily accurate) time stamps on a
>> world-wide network.  That was in the pre-gps, pre-fiber, pre-historic
>> before-times.  I don't think that they ever quite got there. 
> World wide seismology took off in the early 1970s as background for nuclear 
> underground non-testing treaties.  Both the US and the USSR had to be sure 
> they could detect the opponents tests and distinguish tests from earthquakes. 
>  We had seismic stations scattered around the globe.
>
> Does anybody know how they distributed time back then and/or how accurately 
> they could do it?
>
> Google says the speed of sound in rock is 6-8 km/s so 10 ms error would be 
> 100 meters.  That seems like a reasonable ballpark.
>
>
>

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[time-nuts] Magellan GPS OEM 10 CHANNEL looking for pinout or any documentation

[Mariusz Pożoga]

I have few old Magellan GPS OEM 10 CHANNEL gps receiver. I wont use them
as source of pps on some passive radar. I'm looking for pinout or any
manual. If anyone has any information I would be grateful.
Best Regards
Mariusz Pozoga.

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Re: [time-nuts] UPS for my time rack

[Eric Scace]

I’ve used Anderson PowerPoles in mixed voltage environments successfully. A 
visual indication can be obtained by using other colors for the connector 
shell; e.g., red for +13 Vdc and blue for +25 Vdc…

One can also re-orient one of the connectors in each pair by 90º or 180º to 
create a physical incompatibility. This takes some care as the cable ends are 
no longer interchangeable, but it does provide protection against connecting to 
the wrong voltage.

— Eric K3NA

> On 2015 Oct 13, at 16:52 , Florian Teply  wrote:
> 
> Am Tue, 13 Oct 2015 18:54:58 +
> schrieb "Poul-Henning Kamp" :
> 
> […snip…]
> Umm, around here, at least for ham radio operators, it seems many
> standardize now on PowerPole connectors for 12V DC. They are pretty
> affordable, running at below 2 Euro for a single pair. Sure, it's not
> as cheap as an USB connector, but they are designed to handle
> significant currents (15, 30, 45 amps which are freely interchangeable,
> versions rated for 75 or 120 amps exist also).
> 
> Now of course if you want to mix voltage levels, things might become a
> bit more complicated, as most 12V equipment doesn't like to be supplied
> with 24 volts, so it might actually not be the brightest idea to use
> identical connectors in such circumstances. Don't ask how I know... ;-)
> 
> Of course, short circuit currents are the same as before, so properly
> rated fuses and/or circuit breakers are a must, but that would be
> recommended for mains powered equipment as well.
> 
> Best regards,
> Florian


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Re: [time-nuts] How did they distribute time in the old days?

[billriches]

Not milisecond time distribution but time related!

In the early half of the 1900s Western Union was in the time business.  They
would rent businesses such as banks, office buildings, etc  clocks for a few
dollars a month.  These were pendulum wall clocks that had 2 #6 dry cell
batteries inside that would wind them every hour or so. The clocks were
connected to the WU telegraph line and for a minute before and after  the
top of the hour all traffic on the circuit would stop.  Exactly at the top
of the hour they would push a pulse of 50 ? volts or so over the line and it
would reset the clock to the top of the hour.

Eventually WU decided to get out of the time business and stopped the
service and they said all the customers could keep their clocks.  It was
said that at the end of that day many clocks were seen going home with some
of the workers!

I purchased one of these clocks about 15 years ago from a North New Jersey
junk dealer who had obtained several hundred of them.  My clock has a 1929
scratch mark inside and
is still ticking away. These clocks were made by the Self Winding Clock
Company and more information can be seen in the book "American Clocks Volume
2 " by Tran Duy Ly (page 177).  It loses or gains about a minute a month
depending on the moon phase or sunspots.  You can see a pic of the clock on
qrz.com under my call sign.

73,

Bill, WA2DVU
Cape May



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Re: [time-nuts] How did they distribute time in the old days?

[Nick Sayer via time-nuts]

> On Oct 14, 2015, at 4:42 AM, billriches  wrote:
> 
> Not milisecond time distribution but time related!
> 
> In the early half of the 1900s Western Union was in the time business.  They
> would rent businesses such as banks, office buildings, etc  clocks for a few
> dollars a month.  These were pendulum wall clocks that had 2 #6 dry cell
> batteries inside that would wind them every hour or so. The clocks were
> connected to the WU telegraph line and for a minute before and after  the
> top of the hour all traffic on the circuit would stop.  Exactly at the top
> of the hour they would push a pulse of 50 ? volts or so over the line and it
> would reset the clock to the top of the hour.

The WU standard time service goes back further than the turn of the 20th 
century. It started in 1870.

I’ve always wanted to get my hands on one of those clocks and come up with a 
circuit to recreate the synchronization signal for it, probably with a 
Raspberry Pi running ntpd and a big ol’ MOSFET. The problem is that at this 
point, those clocks are quite expensive once they’re reconditioned.

My understanding (perhaps incorrect) was that the sync pulse was once daily 
and, as you said, would cause the hands to “snap” to 12. The trailing edge of 
the pulse was synchronized and would release the clock to operate normally.

That they had something as accurate and widespread as it was so early is 
astonishing.
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Re: [time-nuts] UPS for my time rack

[Gary Woods]

On Wed, 14 Oct 2015 06:34:39 +, you wrote:

>They're quite neat, but I wish there were something a little less
>heavy-duty for the 1-2 Amp range.

For the small stuff, I use the little round plugs that come in a bunch of
sizes; I've tried to standardize my shack on 5.5X2.5mm for things like a
VLF upconverter and a little broadband amplifier mounted in a diecast box
(Who doesn't love Digi-Key?).  But I still put powerpoles with the smaller
contacts on the other end to run on the shack's 12V bus.

-- 
Gary Woods AKA K2AHC- PGP key on request, or at home.earthlink.net/~garygarlic
Zone 5/4 in upstate New York, 1420' elevation. NY WO G
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Re: [time-nuts] UPS for my time rack

[Neil Schroeder]

Depending on your actual power throughput needs- PTCs can be a challenge as
Bob mentions.  You will have a tough time meeting the power requirements of
a Thunderbolt with many you'll see.   Now efuses (think TPS24/25xxx)  or
mosfets with a controller (think LTC43xx) can be a good choice but don't
hesitate to use a real honest to god fuse that blows out and waits for you
to come replace it if that is what you would need

I personally do as suggested in the thread above to some degree- I do AC to
DC conversion once for all my time and frequency stuff then have batteries
local to important gear and (in older stuff) a diode(s) or (in newer stuff)
a real hotswap controller.  But whenever something is really important
there's whatever fuse is needed.

Finally if you are of the type to be adventuresome -
http://cds.linear.com/docs/en/datasheet/4110fb.pdf  or

- Google for Freescale's, ON Semi's or TI's *offline* UPS Reference
designs.  Yes they invert DC to AC, but you can drive the inverter gates
with a microcontoller's PWM output. meaning no matter how jagged your
utility's wave may be you can create a perfect, beautiful 50 or 60 Hz sine
of your own - devoid of most noise.

NS

On Wed, Oct 14, 2015 at 12:01 AM Bob Camp  wrote:

> Hi
>
> One option for the “fuse” part of the DC supply system are PTC resettable
> fuses. You *do* indeed need to be careful about voltage and current ratings
> on these gizmos. If the only objective is to “not have smoke” when there
> is a short,
> that can reduce the variables to a manageable level. If your wire will
> handle 20A for
> long enough to get the gizmo to limit and your load is typically < 5A
> there are
> parts you can find.
>
> A few cautions:
>
> The trip points are very temperature dependent. If you need to handle -20C
> in the winter
> and +40C in the summer, that will narrow things down quite a bit.
>
> Mounting matters quite a bit. If you go with SMD parts, be careful of
> traces that act as
> heatsinks. This is one case that the part needs to get hot.
>
> There are to many variables on most of the spec sheets to simply pick one
> and move on.
> The only good way to do it is to get several and run repeated tests on
> them Min carry current
> will occur at your highest temperature. Worst case trip will occur at your
> lowest temperature.
>
> Consider that the “carry current” may not be the real limitation.
> Resistance in the supply lead
> of an OCXO is a bad idea. This may limit your current well below the point
> that the fuse actually
> trips.
>
> This sounds like a pretty scary list. To some degree it is. These parts do
> have their place. That
> does not mean they work everywhere and anywhere.
>
> Bob
>
> > On Oct 13, 2015, at 2:54 PM, Poul-Henning Kamp 
> wrote:
> >
> > 
> > In message <4FD0F30EBAEF49609DF207E3EE61C15B@pc52>, "Tom Van Baak"
> writes:
> >
> >
> >> I used to rely on one massive UPS (along with natural gas generator)
> >> for my entire lab. Eventually I found it more reliable and convenient
> >> to have localized power backup. By local I mean backup for a single
> >> shelf, or even a single instrument.
> >
> > The big gain is avoiding the DC->AC conversions.
>
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[time-nuts] How did they distribute time in the old days?

[Hal Murray]

hol...@hotmail.com said:
> Somewhat time-nut related...  the project main application needed
> millisecond consistent (not necessarily accurate) time stamps on a
> world-wide network.  That was in the pre-gps, pre-fiber, pre-historic
> before-times.  I don't think that they ever quite got there. 

World wide seismology took off in the early 1970s as background for nuclear 
underground non-testing treaties.  Both the US and the USSR had to be sure 
they could detect the opponents tests and distinguish tests from earthquakes. 
 We had seismic stations scattered around the globe.

Does anybody know how they distributed time back then and/or how accurately 
they could do it?

Google says the speed of sound in rock is 6-8 km/s so 10 ms error would be 
100 meters.  That seems like a reasonable ballpark.



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] UPS, battery backup, and connectors

[Bob Martin]

A lot of ham radio operators, particularly those in involved in emergency 
services use Anderson Powerpole connectors. Easy to install, reliable, 
available. A standard configuration exists for 12 VDC emergency communications 
and mobile work.

bob k6rtm

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Re: [time-nuts] Magellan GPS OEM 10 Channel -- Looking for pinout or any documentation

[Gregory Beat]

What is the I/O Pin Configuration (number/layout) on this GPS receiver?
The earlier Magellan OEM boards used an 8-pin interface (as seen in G8 manual).
Does your Magellan GPS board have these markings (silk-screened on board)??
  MAGELLAN Systems Corporation 
  GPS OEM 10 channel 
  P/N 00-81014-000 
  Date code: 1994 
Magellan did produce a 10-channel receiver, ProMark X, used in some of their 
consumer and OEM aviation/marine products in mid-1990s.
Ashtech G8 GPS OEM Board Reference Manual (circa 1998)
ftp://space.augsburg.edu/processed/MACCS/BU/boston_documentation/manuals/g8.pdf
GG12 OEM Board Reference Manual (circa 2000)
http://ashgps.com/mirror/20130710/OEM,%20Sensor%20&%20ADU/gg12/Reference%20Material/630831%20GG12%20Rev%20A.pdf
A12, B12, & AC12 Reference Manual (circa 2005-2007)
ftp://ftp.ashtech.com/OEM_Sensor_ADU/Legacy%20products/A12,%20%20B12,%20%26%20AC12/Reference%20Material/A12,%20B12%20%26%20AC12%20RM%20rev%20E.pdf
w9gb

> I have few old Magellan OEM 10 Channel GPS receiver. I want use them
> as a source of PPS on some passive radar. I'm looking for pinout or any
> manual. If anyone has any information I would be grateful.
> Best Regards
> Mariusz Pozoga.

History (Smithsonian now has records)
http://amhistory.si.edu/archives/AC1214.html
Ed Tuck of the Boundary Fund, a venture capital firm specializing in 
technologies founded the Magellan Systems Corporation in 1986 and served as its 
director from 1986 to 1993. Tuck assembled the initial team of Norm Hunt, Larry 
Weill, Val Wong, and Sab Ifune to conduct a feasibility study in early 1986 to 
pursue commercial markets for products based on global positioning system (GPS) 
technology. 
Magellan introduced the first handheld commercial GPS receiver in 1989 and was 
the first company to make GPS devices affordable to consumers. Magellan 
introduced the first handheld commercial GPS receiver in 1989 and was the first 
company to make GPS devices affordable to consumers. The company successfully 
introduced GPS products into the marine, professional, military and automotive 
and general aviation markets.
Magellan was purchased by Orbital Sciences Corporation in 1994. 
In 2001, Thales Group purchased the Magellan division of Orbital Sciences, and 
the company became known as Thales Navigation. 
In 2006, a private equity firm, Shah Capital Partners, and other investors 
purchased Thales Navigation, and the company was officially renamed Magellan 
Navigation. Magellan (also known as MiTAC Digital Corporation) is a 
wholly-owned subsidiary of MiTAC International Corporation and promotes and 
sells products and services under the Magellan brand name. 
Magellan is headquartered in Santa Clara, California.
http://www.magellangps.com



Sent from iPad Air
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[time-nuts] How did they distribute time in the old days?

[Mark Sims]

A friend of mine built a clock that they used to time-sync a lot of those 
stations.  It was basically a nice OCXO built into an ammunition can.  They 
flew it to various stations around the world.   One particular trip to sync the 
stations in the mid-east was particularly interesting...  ammo cans,  wires, 
batteries, sketchy looking electronics with counting displays,  clueless 
security goons...  lotsa fun ensued.

> World wide seismology took off in the early 1970s as background for nuclear
> underground non-testing treaties.  Both the US and the USSR had to be sure
> they could detect the opponents tests and distinguish tests from earthquakes.
>   We had seismic stations scattered around the globe. 
>   
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[time-nuts] Why sunspots affect a pendulum?

[iovane--- via time-nuts]

In the other thread "How did they distribute time in the old days?" Bill wrote:
> It loses or gains about a minute a month
>depending on the moon phase or sunspots. 

Why should sunspots affect the rate of a pendulum clock? Sunspots are not 
related to gravity. What about?  Any other kind of clocks is affected by 
sunspots? Who knows? Is what Bill stated reliable? Any paper or website about?I 
would be interested in recorded pendulum clock drift data.
Antonio I8IOV
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Re: [time-nuts] How did they distribute time in the old days?

[Brooke Clarke]

Hi Nick:

One of my Self Winding Clock Co. (WU) clocks was taken down yesterday for 
painting.
When put up one of the Ken's Clock Synchronizers was installed and the hands moved to align with the heart shaped cam it 
uses, but it never worked.
The problem was it used a 4.5 Volt signal which can develop the current needed to pull the sync electromagnet the time 
constant is far too slow.
I'm going to add a high voltage circuit with series resistor to get the time constant down one or two orders of 
magnitude.  The key to this is a PCB I make that holds 5 each 9V batteries connected in series, so I'll use one, two or 
more of them to get the time constant down.

http://www.prc68.com/P/45VS.html

Before I had the 45 Volt Stick I was considering getting the needed high voltage by charging a cap a minute or two 
before the top of the hour and discharging it through a resistor.  Here's a video showing that would work.

http://www.prc68.com/I/SWCC.shtml#Experiments_Feb_2014_

Mail_Attachment --
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Nick Sayer via time-nuts wrote:

On Oct 14, 2015, at 4:42 AM, billriches  wrote:

Not milisecond time distribution but time related!

In the early half of the 1900s Western Union was in the time business.  They
would rent businesses such as banks, office buildings, etc  clocks for a few
dollars a month.  These were pendulum wall clocks that had 2 #6 dry cell
batteries inside that would wind them every hour or so. The clocks were
connected to the WU telegraph line and for a minute before and after  the
top of the hour all traffic on the circuit would stop.  Exactly at the top
of the hour they would push a pulse of 50 ? volts or so over the line and it
would reset the clock to the top of the hour.

The WU standard time service goes back further than the turn of the 20th 
century. It started in 1870.

I’ve always wanted to get my hands on one of those clocks and come up with a 
circuit to recreate the synchronization signal for it, probably with a 
Raspberry Pi running ntpd and a big ol’ MOSFET. The problem is that at this 
point, those clocks are quite expensive once they’re reconditioned.

My understanding (perhaps incorrect) was that the sync pulse was once daily 
and, as you said, would cause the hands to “snap” to 12. The trailing edge of 
the pulse was synchronized and would release the clock to operate normally.

That they had something as accurate and widespread as it was so early is 
astonishing.
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Re: [time-nuts] How did they distribute time in the old days?

[Bill Hawkins]

The book "Einstein's Clocks, Poincare's Maps" describes a pneumatic time
sync method for the public clocks on poles in the city of Paris, France
in the late 1800s. Pneumatic clocks were made and used in the US for a
while. Got one from the four letter auction site and dreamed of making a
pneumatic pulse generator synched to 10 MHz. Sadly, the diaphragm in the
pneumatic mechanism had rotted away, so I gave the clock to a friend who
could make it work, but didn't. One pulse advanced the clock one minute.
There was no auxiliary clockwork to keep it running between hourly sync
pulses.

I don't know of any mechanical clocks that sync once a day. IIRC,
Western Union had to send people to advance or retard the hour hand when
daylight savings time became common.

There is something about those clocks that makes a time nut want to
restore one.

Bill Hawkins


-Original Message-
From: Nick Sayer via time-nuts
Sent: Wednesday, October 14, 2015 11:42 AM

The WU standard time service goes back further than the turn of the 20th
century. It started in 1870.

I've always wanted to get my hands on one of those clocks and come up
with a circuit to recreate the synchronization signal for it, probably
with a Raspberry Pi running ntpd and a big ol' MOSFET. The problem is
that at this point, those clocks are quite expensive once they're
reconditioned.

My understanding (perhaps incorrect) was that the sync pulse was once
daily and, as you said, would cause the hands to "snap" to 12. The
trailing edge of the pulse was synchronized and would release the clock
to operate normally.

That they had something as accurate and widespread as it was so early is
astonishing.

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Re: [time-nuts] How did they distribute time in the old days?

[Jim Harman]

The Western Union clocks were still in use at broadcast stations in the
early 1970s. One problem was that the reset pulse and resulting jump in
time would come exactly on the hour, when you were trying to synchronize
with a network news broadcast that began at the network's version of 00:00.

ABC and I presume the other networks would send a tone 10 seconds before
their program started, By listening to the network on the "Cue" channel,
you would have a pretty good idea of when the news would start.

Another system in wide use around then and still somewhat today for
controlling the clocks in a large building was sold by Simplex. The
building would have a master clock (set manually by the custodian or
whoever) that pumped out tones at about 3 KHz over the power lines. These
signals would come out a couple of minutes before the hour, presumably to
avoid problems with events scheduled on the hour. The slave clocks were
designed to run a little fast, and would wait at 58:00 until they received
a tone to restart. I believe there was a special tone that would make the
clock run "fast forward," to deal with longer adjustments for power outages
and DST.

One drawback of this system is that the tones sometimes leak into audio
equipment, and in a quiet room they are often audible through the
fluorescent light ballasts.

On Wed, Oct 14, 2015 at 12:42 PM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

>
>
>
> The WU standard time service goes back further than the turn of the 20th
> century. It started in 1870.
>
> --

--Jim Harman
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Re: [time-nuts] How did they distribute time in the old days?

[bownes]

And to tie this back to the UPS thread, at university, the Simplex clock sync 
signal made our Vax 11/730 TOD clock run wy fast. 
I never figured out if it was using line frequency zero crossings for seconds 
or if it was leaking as DEC fixed it not long after it was installed. (And it 
was moved to a different phase of the power system than the clocks...)



> On Oct 14, 2015, at 15:55, Jim Harman  wrote:
> 
> The Western Union clocks were still in use at broadcast stations in the
> early 1970s. One problem was that the reset pulse and resulting jump in
> time would come exactly on the hour, when you were trying to synchronize
> with a network news broadcast that began at the network's version of 00:00.
> 
> ABC and I presume the other networks would send a tone 10 seconds before
> their program started, By listening to the network on the "Cue" channel,
> you would have a pretty good idea of when the news would start.
> 
> Another system in wide use around then and still somewhat today for
> controlling the clocks in a large building was sold by Simplex. The
> building would have a master clock (set manually by the custodian or
> whoever) that pumped out tones at about 3 KHz over the power lines. These
> signals would come out a couple of minutes before the hour, presumably to
> avoid problems with events scheduled on the hour. The slave clocks were
> designed to run a little fast, and would wait at 58:00 until they received
> a tone to restart. I believe there was a special tone that would make the
> clock run "fast forward," to deal with longer adjustments for power outages
> and DST.
> 
> One drawback of this system is that the tones sometimes leak into audio
> equipment, and in a quiet room they are often audible through the
> fluorescent light ballasts.
> 
> On Wed, Oct 14, 2015 at 12:42 PM, Nick Sayer via time-nuts <
> time-nuts@febo.com> wrote:
> 
>> 
>> 
>> 
>> The WU standard time service goes back further than the turn of the 20th
>> century. It started in 1870.
>> 
>> --
> 
> --Jim Harman
> ___
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Re: [time-nuts] How did they distribute time in the old days?

[Brian Inglis]

On 2015-10-14 10:42, Nick Sayer via time-nuts wrote:



On Oct 14, 2015, at 4:42 AM, billriches  wrote:

Not milisecond time distribution but time related!

In the early half of the 1900s Western Union was in the time business.  They
would rent businesses such as banks, office buildings, etc  clocks for a few
dollars a month.  These were pendulum wall clocks that had 2 #6 dry cell
batteries inside that would wind them every hour or so. The clocks were
connected to the WU telegraph line and for a minute before and after  the
top of the hour all traffic on the circuit would stop.  Exactly at the top
of the hour they would push a pulse of 50 ? volts or so over the line and it
would reset the clock to the top of the hour.


The WU standard time service goes back further than the turn of the 20th 
century. It started in 1870.

I’ve always wanted to get my hands on one of those clocks and come up with a 
circuit to recreate the synchronization signal for it, probably with a 
Raspberry Pi running ntpd and a big ol’ MOSFET. The problem is that at this 
point, those clocks are quite expensive once they’re reconditioned.

My understanding (perhaps incorrect) was that the sync pulse was once daily 
and, as you said, would cause the hands to “snap” to 12. The trailing edge of 
the pulse was synchronized and would release the clock to operate normally.

That they had something as accurate and widespread as it was so early is 
astonishing.


Ingenuity was never lacking - a few quotes from
https://archive.org/details/GreenwichTime - well researched and still
available in a later edition - includes many incidents which I found
humorous - the first ilustrating that TWTT long predated Cs clocks:

""Difference of longitude can be determined astronomically or geodesically (by
trigonometrical-survey methods) or, as we have seen, by the transport of
chronometers. One of the earliest examples of the use of this last method took
place during the geodetic operation to connect Paris and Greenwich
Observatories in 1784-8, instigated by Cassini de Thury and conducted on the
English side of the Channel by Major-General William Roy, FRS. In September
1785 Maskelyne sent his assistant Joseph Lindley by post-chaise and
cross-channel packet to Paris and back carrying eight of John Arnold's
chronometers, yielding a difference of longitude of 9 minutes 19.8 seconds,
only about a second too small and agreeing well with the existing astronomical
determinations and the geodetic result. 1 In 1825 a series of rockets was used
by John Herschel and Col. Sabine to connect Paris and Greenwich. The
chronometer method continued to be used for longitude determination of
observatories until the coming of the electric telegraph. For example, in 1843
more than sixty chronometers were sent sixteen times backwards and forwards
between Altona near Hamburg and Pulkowa near today's Leningrad, and the
following year forty chronometers went the same number of times between Altona
and Greenwich. Chronometers were sent across the Atlantic many times to
determine the longitude difference between Harvard and Liverpool Observatories,
from which the difference of longitude between Harvard and Greenwich was
accurately determined. In 1844 the longitude of Valentia Island and the west
coast of Ireland was found in this way, under Airy's superintendence."

"The use of the electric telegraph for this purpose was first suggested by the
American astronomer S. C. Walker and first used in the USA about 1849. As we
have seen, the telegraphic connections between Greenwich and the Continent were
suggested by Airy in 1851, connection with Brussels being established in 1853,
and with Paris in 1854. The longitude of Valentia was redetermined by telegraph
in 1862."

"The first successful submarine cable was laid across the English Channel in
1851. Wales and Scotland were linked with Ireland in 1852, England with Belgium
and Denmark in 1853. By 1860 London was connected with the Indian subcontinent,
one of the longest submarine cables being between Malta and Alexandria, 1,565
miles. But the really exciting prospect was a cable - perhaps more than one
-between Europe and North America. Its main protagonist was the great American
Cyrus W. Field (1819-92), whose untiring efforts provided the impetus
throughout."

"The next year, however, a new cable was successfully laid by the Great Eastern,
taking fourteen days from Valentia to Heart's Content in Newfoundland. To
complete the triumph, the Great Eastern successfully grappled the 1865 cable,
spliced it on to cable remaining on board, and thus provided a second cable
link across the Atlantic.

One of the factors leading to this success was that during the 1866 lay, at the
suggestion of Captain Anderson, the Greenwich time signal was received by the
Great Eastern twice daily by telegraph via London, Holyhead, Dublin, Valentia,
and the cable she was laying, thus enabling her to find her longitude exactly.
This 

Re: [time-nuts] How did they distribute time in the old days?

[Bob Bownes]

Precise time (and time zones) and the relationship with the telegraph were
a side effect of the railroads. You need to keep time (and keep on time) in
order to avoid collisions on single tracked main lines.

On Wed, Oct 14, 2015 at 12:42 PM, Nick Sayer via time-nuts <
time-nuts@febo.com> wrote:

>
> > On Oct 14, 2015, at 4:42 AM, billriches  wrote:
> >
> > Not milisecond time distribution but time related!
> >
> > In the early half of the 1900s Western Union was in the time business.
> They
> > would rent businesses such as banks, office buildings, etc  clocks for a
> few
> > dollars a month.  These were pendulum wall clocks that had 2 #6 dry cell
> > batteries inside that would wind them every hour or so. The clocks were
> > connected to the WU telegraph line and for a minute before and after  the
> > top of the hour all traffic on the circuit would stop.  Exactly at the
> top
> > of the hour they would push a pulse of 50 ? volts or so over the line
> and it
> > would reset the clock to the top of the hour.
>
> The WU standard time service goes back further than the turn of the 20th
> century. It started in 1870.
>
> I’ve always wanted to get my hands on one of those clocks and come up with
> a circuit to recreate the synchronization signal for it, probably with a
> Raspberry Pi running ntpd and a big ol’ MOSFET. The problem is that at this
> point, those clocks are quite expensive once they’re reconditioned.
>
> My understanding (perhaps incorrect) was that the sync pulse was once
> daily and, as you said, would cause the hands to “snap” to 12. The trailing
> edge of the pulse was synchronized and would release the clock to operate
> normally.
>
> That they had something as accurate and widespread as it was so early is
> astonishing.
> ___
> 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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Re: [time-nuts] How did they distribute time in the old days?

[billriches]

I have been using 2 D cells in series to wind my clock - Every Labor Day I 
change the batteries!  Has anyone used Ken's for a rebuild.  Mine is still 
chugging along - amazing as some of the bushings are ovals and the gears can 
really move around in them!!

73,

Bill

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke
Sent: Wednesday, October 14, 2015 2:02 PM
To: Nick Sayer; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] How did they distribute time in the old days?

Hi Nick:

One of my Self Winding Clock Co. (WU) clocks was taken down yesterday for 
painting.
When put up one of the Ken's Clock Synchronizers was installed and the hands 
moved to align with the heart shaped cam it uses, but it never worked.
The problem was it used a 4.5 Volt signal which can develop the current needed 
to pull the sync electromagnet the time constant is far too slow.
I'm going to add a high voltage circuit with series resistor to get the time 
constant down one or two orders of magnitude.  The key to this is a PCB I make 
that holds 5 each 9V batteries connected in series, so I'll use one, two or 
more of them to get the time constant down.
http://www.prc68.com/P/45VS.html

Before I had the 45 Volt Stick I was considering getting the needed high 
voltage by charging a cap a minute or two before the top of the hour and 
discharging it through a resistor.  Here's a video showing that would work.
http://www.prc68.com/I/SWCC.shtml#Experiments_Feb_2014_

Mail_Attachment --
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Nick Sayer via time-nuts wrote:
>> On Oct 14, 2015, at 4:42 AM, billriches  wrote:
>>
>> Not milisecond time distribution but time related!
>>
>> In the early half of the 1900s Western Union was in the time 
>> business.  They would rent businesses such as banks, office 
>> buildings, etc  clocks for a few dollars a month.  These were 
>> pendulum wall clocks that had 2 #6 dry cell batteries inside that 
>> would wind them every hour or so. The clocks were connected to the WU 
>> telegraph line and for a minute before and after  the top of the hour 
>> all traffic on the circuit would stop.  Exactly at the top of the 
>> hour they would push a pulse of 50 ? volts or so over the line and it would 
>> reset the clock to the top of the hour.
> The WU standard time service goes back further than the turn of the 20th 
> century. It started in 1870.
>
> I’ve always wanted to get my hands on one of those clocks and come up with a 
> circuit to recreate the synchronization signal for it, probably with a 
> Raspberry Pi running ntpd and a big ol’ MOSFET. The problem is that at this 
> point, those clocks are quite expensive once they’re reconditioned.
>
> My understanding (perhaps incorrect) was that the sync pulse was once daily 
> and, as you said, would cause the hands to “snap” to 12. The trailing edge of 
> the pulse was synchronized and would release the clock to operate normally.
>
> That they had something as accurate and widespread as it was so early is 
> astonishing.
> ___
> 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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---
This email has been checked for viruses by Avast antivirus software.
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Re: [time-nuts] How did they distribute time in the old days?

[Don Couch]

Hi, Brooke,

My self winding clock synchronizes fine on three volts. I built a 
synchronizer using a PIC controller with a 32KHz quartz crystal, running 
on three volts. You might want to carefully check the coil and 
connections on yours. By the way, the winding coils also are running on 
three volts.


Don Couch

On 10/14/2015 11:02 AM, Brooke Clarke wrote:

Hi Nick:

One of my Self Winding Clock Co. (WU) clocks was taken down yesterday 
for painting.
When put up one of the Ken's Clock Synchronizers was installed and the 
hands moved to align with the heart shaped cam it uses, but it never 
worked.
The problem was it used a 4.5 Volt signal which can develop the 
current needed to pull the sync electromagnet the time constant is far 
too slow.
I'm going to add a high voltage circuit with series resistor to get 
the time constant down one or two orders of magnitude.  The key to 
this is a PCB I make that holds 5 each 9V batteries connected in 
series, so I'll use one, two or more of them to get the time constant 
down.

http://www.prc68.com/P/45VS.html

Before I had the 45 Volt Stick I was considering getting the needed 
high voltage by charging a cap a minute or two before the top of the 
hour and discharging it through a resistor.  Here's a video showing 
that would work.

http://www.prc68.com/I/SWCC.shtml#Experiments_Feb_2014_

Mail_Attachment --
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Nick Sayer via time-nuts wrote:
On Oct 14, 2015, at 4:42 AM, billriches  
wrote:


Not milisecond time distribution but time related!

In the early half of the 1900s Western Union was in the time 
business.  They
would rent businesses such as banks, office buildings, etc clocks 
for a few
dollars a month.  These were pendulum wall clocks that had 2 #6 dry 
cell

batteries inside that would wind them every hour or so. The clocks were
connected to the WU telegraph line and for a minute before and 
after  the
top of the hour all traffic on the circuit would stop. Exactly at 
the top
of the hour they would push a pulse of 50 ? volts or so over the 
line and it

would reset the clock to the top of the hour.
The WU standard time service goes back further than the turn of the 
20th century. It started in 1870.


I’ve always wanted to get my hands on one of those clocks and come up 
with a circuit to recreate the synchronization signal for it, 
probably with a Raspberry Pi running ntpd and a big ol’ MOSFET. The 
problem is that at this point, those clocks are quite expensive once 
they’re reconditioned.


My understanding (perhaps incorrect) was that the sync pulse was once 
daily and, as you said, would cause the hands to “snap” to 12. The 
trailing edge of the pulse was synchronized and would release the 
clock to operate normally.


That they had something as accurate and widespread as it was so early 
is astonishing.

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Re: [time-nuts] How did they distribute time in the old days?

[Hal Murray]

bow...@gmail.com said:
> I never figured out if it was using line frequency zero crossings for
> seconds or if it was leaking as DEC fixed it not long after it was
> installed. (And it was moved to a different phase of the power system than
> the clocks...) 

I remember a story from ages ago...  A machine was keeping crappy time.  It 
was a 60 Hz box running in a 50 Hz country.  Things got a lot better after 
the frequency converter box was adjusted.

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] UPS for my time rack

[Bob Camp]

Hi

> On Oct 14, 2015, at 2:34 AM, Poul-Henning Kamp  wrote:
> 
> 
> In message <20151013225202.1e70a...@aluminium.mobile.teply.info>, Florian 
> Teply
> writes:
> 
>> DC-DC converters with very
>> good efficiency exist for quite some time now.
> 
> The one I just put in my HP5065A does 60W with 90+% efficiency
> in a 2x1x.5 inch package:
> 
>   http://phk.freebsd.dk/hacks/HP5065A/20150930_dcdc/index.html
> 
>> Umm, around here, at least for ham radio operators, it seems many
>> standardize now on PowerPole connectors for 12V DC.
> 
> They're quite neat, but I wish there were something a little less
> heavy-duty for the 1-2 Amp range.

So far my answer to that has been the coaxial power plug that you see on a lot 
of wall chargers.
Pick a size and have them ship you a bucket full of pre-made cables for next to 
nothing. The cables
with both male and female ends are cheaper than the ones with tinned leads on 
one end (go figure …). 
That makes the “which one do I buy” decision pretty easy. Once they come in and 
you chop them up, a 
bit of quality time with the soldering iron gives you a reasonable inventory of 
power squids to distribute 
your +6, +12 or +24V.

Bob

> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> ___
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[time-nuts] 3GHz prescaler for Pendulum counters

[GandalfG8--- via time-nuts]

A couple of years ago, my oh my doesn't time rush by when you're having  
fun?:-), I posted a recommendation for 3GHz prescalers from Pawel Witkowski, 
an  Ebay seller in Poland, for the HP 53131 and 53132 counters.
 
I'm now very happy to report that Pawel has also produced a similar  
prescaler for the Pendulum range of counters, his Ebay ID is pa-fko and a  
typical 
auction is 111794690250.
 
Pawel actually lists these as being for the Philips/Fluke PM6685,  this 
being the counter he designed them for, and with a comment  that they also work 
with the PM6680, but those are rebadged Pendulum  counters and a look at 
the service manuals suggested that  the original  Pendulum prescalers were 
likely to be a one module fits all solution, and  this has turned out to be the 
case.
 
For the past few weeks I've been using a pair of these modules,  one fitted 
to a CNT90 and the other to a Tekktronix FCA3100, which is a  rebadged 
CNT91, and I'm very happy with the results.
Once installed the counter automatically recognises that it now has an  
input "C", and that's all there is to it.
The built in statistical plotting options work for input C just as they do  
for inputs A and B, but note that the level measuring functions of inputs A 
and  B are hardware dependent and aren't available for input C, this also 
applies to  the original Pendulum prescalers.
 
There's a graph of measured sensitivity and "application area" included  
with the auction photos and I'm seeing results that agree closely with that. 
Up  to 1GHz I've run tests using a Marconi 2022E signal generator and above 
that  I've been playing with a Chinese clone of the Anolog ADF4351 evaluation 
kit. I  don't have any independent means of checking the levels from the 
ADF4351 kit  above 1.5GHz but I've no reason to believe it's not performing as 
it should,  certainly the frequency accuracy is as expected.
 
The service manuals indicate that later models have extra pins on  the 
prescaler connector but the functions of the rear sixteen pins have  remained 
unchanged, and ensuring that the prescaler is mounted to the rear  of the 
connector, regardless of the number of pins that leaves spare, is all  that's 
required.
 
 
A couple of points to note, the mounting  clips shown in the auction photos 
are already fitted to the PM6685 but  were not fitted to my CNT90 or 
FCA3100, so these had to be supplied with the  prescaler. Anyone ordering these 
should make it clear what counter they will  fitted to.
There are two predrilled 2.5mm diameter holes in the  front panel for the N 
connector that will accept M2.5 screws but the shape of  the casting does 
not allow any nuts to be fitted.
The prescaler board is provided with self tapping  screws, although I chose 
to run an M3 tap through the holes and use  standard screws, but I suspect 
the best solution would  probably be to use M3 Taptite screws.

 
For anyone who might be interested I've uploaded a file containing a set of 
 similar photos for each counter showing stages of the installation, and 
also  some photos of the counters under test and the ADF4351 module..
   
https://mega.nz/#!qNYiDCzC!HHWEpI8TUDW6VO_fuyk34uU6Tr4V-pXRLru-DMtaq2
 
Apologies for the messy looking link, it's nothing  sinister, just that the 
site encrypts all files and most of that link is the  decryption key.
 
For these tests, both counters and both frequency sources  were referenced 
to the same Trimble Thunderbolt.
 
At 1GHz, using the Marconi 2022 signal generator,  I checked sensitivity 
down to -40dBm, possibly could have gone lower but  didn't see too much need 
for that:-)
 

The ADF4351 evaluation kit only has selectable output levels of +5, +2, -1, 
 and -4 dBm, so for higher frequencies I took a different approach  and 
tested for the maximum frequency that would display properly on the  counter at 
levels of -4dBm, as indicated by the ADF4351 software, and also  at -7dBm 
and -10dBm by adding attenuators.
The module was mounted a very short distance from the  counter using 
semi-rigid coax  to an SMA to N adapter, again  this can be seen in the photos, 
 
and 23GHz rated Aeroflex  3dB SMA attenuators were added directly between the 
synthesiser module and  the counter input, although this is not shown.
 
Both counters worked fine at 3.00 GHz with the -4dBm signal and whilst  
there was a difference between the two counters as the frequency increased  
it's obvious that both would have worked fine at 3.00GHz with the -7dBm  signal 
also and very close at -10dBm.
It might be interesting to swap the modules between counters, to  see if 
that has any effect on the overall sensitivity at higher  frequencies but it's 
not something I've tried so far, and I don't see it as  a problem either 
way.
 
With the FCA3100 (CNT91), the limits I measured were.
at -4dBm    3.500GHz
at -7dBm    3.400GHz
at -10dBm  ---  3.325 GHz
 
With the CNT90, the limits I measured were..
at -4dBm    3.200GHz
at -7dBm 

[time-nuts] Pendulum Counter Service Manuals

[GandalfG8--- via time-nuts]

Spectracom have always seemed a bit "cautious" when it comes to releasing  
copies of the Pendulum Counter service manuals, I was sent a copy of the  
CNT90/91 manual when carrying out some repairs a few years ago but  only after 
accepting a non disclosure agreement.
 
Because of that I was quite surprised recently to find that Fluke have  
released the full service manual for many of their equivalents to the  Pendulum 
counters, with these seeming to be identical to the  pendulum originals but 
with name and model numbers changed.
A similar situation exists for the Fluke and Pendulum user manuals but in  
this case both are widely available anyway.
 
Recent searches have turned up service manuals for PM6680/CNT80,  
PM6681/CNT81, PM6685/CNT85, PM6690/CNT90.
 
The only exception seems to be the CNT91, and as far as I can tell  there 
never was a Fluke PM6691.
The Pendulum CNT90/91 manual includes the revision A and B boards for the  
CNT90 as well as the later revision C used in the CNT91, whereas the Fluke  
PM6690 manual has no reference to the later board but does otherwise seem  
identical.
 
Apologies if this is already common knowledge but I don't recall  seeing 
any previous reference to it and thought it might of interest  to other 
Pendulum users.
 
Regards
 
Nigel
GM8PZR
 
 
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Re: [time-nuts] Why sunspots affect a pendulum?

[iovane--- via time-nuts]

>Antonio - that sunspot comment was made as a joke!
>
>73,
>
>Bill

Ok, I really didn't realize this.
73,
Antonio

>
>-Original Message-
>From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of iovane---
>via time-nuts
>Sent: Wednesday, October 14, 2015 12:31 PM
>To: time-nuts@febo.com
>Subject: [time-nuts] Why sunspots affect a pendulum?
>
>In the other thread "How did they distribute time in the old days?" Bill
>wrote:
>> It loses or gains about a minute a month depending on the moon phase 
>>or sunspots.
>
>Why should sunspots affect the rate of a pendulum clock? Sunspots are not
>related to gravity. What about?  Any other kind of clocks is affected by
>sunspots? Who knows? Is what Bill stated reliable? Any paper or website
>about?I would be interested in recorded pendulum clock drift data.
>Antonio I8IOV

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Re: [time-nuts] Why sunspots affect a pendulum?

[billriches]

Antonio - that sunspot comment was made as a joke!

73,

Bill

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of iovane---
via time-nuts
Sent: Wednesday, October 14, 2015 12:31 PM
To: time-nuts@febo.com
Subject: [time-nuts] Why sunspots affect a pendulum?

In the other thread "How did they distribute time in the old days?" Bill
wrote:
> It loses or gains about a minute a month depending on the moon phase 
>or sunspots.

Why should sunspots affect the rate of a pendulum clock? Sunspots are not
related to gravity. What about?  Any other kind of clocks is affected by
sunspots? Who knows? Is what Bill stated reliable? Any paper or website
about?I would be interested in recorded pendulum clock drift data.
Antonio I8IOV
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Re: [time-nuts] UPS for my time rack

[Neil Schroeder]

Those traco power units are fantastic. Absolutely great.

For smaller applications Murata makes 3W ones quite similar and Wurth
Electronik is also in that market.

On Wed, Oct 14, 2015 at 12:00 PM Poul-Henning Kamp 
wrote:

> 
> In message <20151013225202.1e70a...@aluminium.mobile.teply.info>, Florian
> Teply
>  writes:
>
> >DC-DC converters with very
> >good efficiency exist for quite some time now.
>
> The one I just put in my HP5065A does 60W with 90+% efficiency
> in a 2x1x.5 inch package:
>
> http://phk.freebsd.dk/hacks/HP5065A/20150930_dcdc/index.html
>
> >Umm, around here, at least for ham radio operators, it seems many
> >standardize now on PowerPole connectors for 12V DC.
>
> They're quite neat, but I wish there were something a little less
> heavy-duty for the 1-2 Amp range.
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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>
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