Re: [time-nuts] Parallel voltage regulators

[Bill Hawkins]

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There is a concept in temperature control called feed-forward.

In this case you would sample the supply line with an inverting
amplifier and use it to increase the oven drive signal as the
line voltage decreases. The goal is to keep the integral term
from changing as the line voltage changes. It is not as easy
as it sounds.

Bill Hawkins


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Re: [time-nuts] Parallel voltage regulators

[Don Collie]

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Surely there will be an improvement in oven temparature regulation, by using 
a regulated supply, but whether or not this improvment is marginal or 
significant would have to be determined either by experiment [my favourite], 
or calculation. As you say Chuck : it`s eliminating [or reducing the effect 
of] one variable in the equation.
Cheers,Don.


- Original Message - 
From: "Chuck Harris" <[EMAIL PROTECTED]>
To: "Discussion of precise time and frequency measurement" 

Sent: Friday, October 26, 2007 12:29 PM
Subject: Re: [time-nuts] Parallel voltage regulators


> ); SAEximRunCond expanded to false
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>
> The simple answer is if the heater supply in unregulated, and the
> supply changes, it will take a little while before the heater control
> loop can compensate.  While this is happening, the oven temperature
> will be slightly wrong, and the crystal frequency will be offset.
> Voltage regulation adds one more level of isolation to the oven 
> temperature
> from changes in raw supply voltage.
>
> -Chuck Harris
>
> Matt Ettus wrote:
>> ); SAEximRunCond expanded to false
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>>
>> This may be a bit late in this [strangely contentious] discussion, but
>> I have to ask why you need to regulate the heater voltage?  If the
>> voltage varies, the control loops will adjust accordingly.  Unless the
>> input voltage is higher than some safe range for the heater circuitry.
>>
>> Matt
>>
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Re: [time-nuts] QCM

[Bernd T-Online]

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Hi John,

Neon John wrote:
> A somewhat related question.  Can a quartz crystal be used as a pressure 
> (actually
> medium to high vacuum) sensor?  Specifically, over the range of perhaps 1 
> Torr to
> 1e-6 Torr.  IOW, over about the same range as a thermocouple gauge.
>
> At first blush it would seem a natural application.  Not knowing what the 
> second
> blush is :-)
First of all there would not be much frequency change compared to the 
undesired effects from temperature, aging, and probably hysteresis for a 
one Torr pressure difference, and the scale would not be logarithmic as 
desired by a vacuum meter. In principle such a sensor would work only, 
if you put the crystal into a box, which is sealed at a reference 
pressure, and a mechanical force proportional to the pressure difference 
is suitably applied to the crystal through a membrane.
So such a sensor would be rather complex and would have very low 
sensitivity with a linear scale from 0 Torr to 1 Torr - which is 
probably not what you wanted to consider.

Regards

Bernd
DK1AG
www.qsl.net/dk1ag




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Re: [time-nuts] Scopes and 1 PPS signals?

[Didier Juges]

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Glad it works. I found the same here and that's why the better pictures were
made with a 5600pF cap that just happened to lay on the bench...

Didier 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke
> Sent: Thursday, October 25, 2007 1:25 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Scopes and 1 PPS signals?
> 
> Hi Didier:
> 
> When just a diode is used the stretching is only at the 
> bottom of the trailing edge and not enough to help.  But when 
> a little capacitance is added it works.
> 
> The period is the same as what the SR620 reported, 1/ 32 Hz.  
> Seems a strange number.
> 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> http://www.precisionclock.com
> http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
> 
> 
> Didier Juges wrote:
> > Some DSOs (my lowly Tek 210 does) have a peak detect 
> acquisition mode 
> > where it will analyze the signal at the highest speed of the A/D 
> > converter regardless of sweep speed and report the min and max for 
> > each displayed pixel line. Main advantages are 1) to make aliasing 
> > obvious and 2) to be able to see very narrow pulses at low sweep 
> > speed. I can see 20nS wide pulses at 1 PPS easily. Of course, the 
> > precision of the measurement (if you use the period function) is 
> > limited to the display resolution, but at least you can get in the 
> > ballpark. My scope is in that mode all the time, little 
> reason not to.
> > 
> > If you do not have such mode, put a diode (i.e. 1N4148) in 
> series with 
> > the probe. The diode will charge the input capacitance of 
> the probe, 
> > which will discharge exponentially in the 10 Mohm 
> resistance and give 
> > you something you can see. Can't beat that for cost. Add some 
> > capacitance in parallel with the probe if needed to widen the pulse.
> > 
> > Didier KO4BB
> > 
> > 
> >>-Original Message-
> >>From: [EMAIL PROTECTED]
> >>[mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke
> >>Sent: Tuesday, October 23, 2007 6:24 PM
> >>To: Discussion of precise time and frequency measurement
> >>Subject: Re: [time-nuts] Scopes and 1 PPS signals?
> >>
> >>Hi Bill:
> >>
> >>I'm sure that would work, but it's something else that needs to be 
> >>done sometime in the future.
> >>
> >>I checked the pulse coming from the M12+T and it's more like 100 ms 
> >>wide, probably for this reason.
> >>
> >>Have Fun,
> >>
> >>Brooke Clarke
> >>http://www.PRC68.com
> >>http://www.precisionclock.com
> >>http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
> >>
> >>
> >>WB6BNQ wrote:
> >>
> >>>Hi Brook,
> >>>
> >>>You could try using a 74123 (or newer variants)
> >>
> >>retriggerable one shot
> >>
> >>>to extend the pulse width to a level that would allow you
> >>
> >>to see it on the scope.
> >>
> >>>BillWB6BNQ
> >>>
> >>>Brooke Clarke wrote:
> >>>
> >>>
> >>>
> Hi:
> 
> While trying to figure out the O-1814 Rb source I found a 1
> >>
> >>PPS signal
> >>
> that's less than 10 us wide.  But using an HP 54501A DSO
> >>
> >>it's almost
> >>
> impossible to determine the period.  
> http://www.prc68.com/I/O1814.shtml
> 
> If the display is 1,000 dots wide:
> at 2 us/sq the trace takes up about 4.5 squares or 450 
> dots, at 200 
> us/sq the trace takes up about 0.045 squares or 4 dots but
> >>
> >>the second
> >>
> pulse is way off screen.  At slower sweep speeds you can't
> >>
> >>see the pulse.
> >>
> Are there scopes that allow the period of a narrow pulse to be 
> measured that don't cost an arm and leg?
> 
> --
> Have Fun,
> 
> Brooke Clarke
> > 
> > 
> > 
> > ___
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> 
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Re: [time-nuts] M100.pdf

[Didier Juges]

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Hi guys,

Yes it's still in the upload section.

At the moment, my uplink is busy uploading ~2.5 GB of manuals donated by
someone, so I'll get to the M100 as soon as possible. I'll be out of town
tomorrow, so it may be Saturday.

Anyone can download from the upload section though. Just use the same
instruction as you did for upload.

Didier KO4BB


> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of John Day
> Sent: Thursday, October 25, 2007 7:30 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] M100.pdf
> 
> At 06:31 PM 10/25/2007, you wrote:
> >John
> >It's probably still in the upload section Phil G4FXY
> 
> Aaahh! Then I am sure it will make it out very soon.
> 
> Thanks
> 


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Re: [time-nuts] M100.pdf

[John Day]

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At 06:31 PM 10/25/2007, you wrote:
>John
>It's probably still in the upload section
>Phil G4FXY

Aaahh! Then I am sure it will make it out very soon.

Thanks


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Re: [time-nuts] Parallel voltage regulators

[Bruce Griffiths]

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Magnus Danielson wrote:
> From: Bruce Griffiths <[EMAIL PROTECTED]>
> Subject: Re: [time-nuts] Parallel voltage regulators
> Date: Thu, 25 Oct 2007 17:42:51 +1300
> Message-ID: <[EMAIL PROTECTED]>
>
>   
>> Don Collie wrote:
>> 
>>> Hi Tom,
>>> If you really want to regulate the oven`s supply voltage, my National 
>>> Voltage Regulator handbook shows that the LM317T will supply over 2 Amps, 
>>> with an input/output differential of between 5, and 12.5 Volts. A single 
>>> one 
>>> of these should do the job OK.
>>> Cheers!,.Don Collie jnr.
>>>
>>>   
>>>   
>> Never rely on typical specs always use the minimum spec which is 1.5A
>> not quite enough.
>> 
>
> You want design-margin. Some of that toll will be in less than optimum 
> heating,
> some will be in less heating in the first place (compared to upper limit) and
> for a power regulating aspect, headroom allows better regulations.
>
> In one design we had to parallel the regulators since the regulator the
> designer put in just barely was able to regulate the CPU core voltage.
> It worked, but at just rebooted at some vauge point an the memory tests.
> What actually happend was that as soon as it started to actually do anything,
> the regulator was running at its limit and output voltage dropped as the
> current was rising and the voltage supervision pulled the RESET.
>
> That's what you get from reading the typical reading on the CPU current and
> match that with the maximum rating of the power regulator. A no margin design.
> That designer had a few more flaws which was creeping around in that design,
> but let's not bring that can of worms open here. :)
>
> The 5A LM338 will be just fine. Infact, you can pull 8A out of it under
> certain conditions.
>
> Cheers,
> Magnus
>
>   

Hej Magnus

The LM338 thermal design is also much easier (it has a much lower
junction to case thermal resistance than an LM317) especially if the
circuit is intended to operate over wide temperature (0 -40C or more)
and mains voltage ranges (+-10% or more).

The alleged problem with the high short circuit current is easily solved
by using diodes with adequate current ratings in conjunction with a fuse
to protect the transformer if it isnt rated to produce an 8A dc output.

The startup current of the load (rubidium standard) may also vary with
temperature and /or input voltage.
Either  find the manufacturers specifications or allow adequate margins.

Worst case design is desirable even for one off circuits especially if
the circuit is published.
When the design is  publicly available one is in effect transferring the
production run problems associated with a marginal design to many
individuals rather than a single factory or production line.

Bruce




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Re: [time-nuts] Parallel voltage regulators

[Chuck Harris]

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The simple answer is if the heater supply in unregulated, and the
supply changes, it will take a little while before the heater control
loop can compensate.  While this is happening, the oven temperature
will be slightly wrong, and the crystal frequency will be offset.
Voltage regulation adds one more level of isolation to the oven temperature
from changes in raw supply voltage.

-Chuck Harris

Matt Ettus wrote:
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> This may be a bit late in this [strangely contentious] discussion, but
> I have to ask why you need to regulate the heater voltage?  If the
> voltage varies, the control loops will adjust accordingly.  Unless the
> input voltage is higher than some safe range for the heater circuitry.
> 
> Matt
> 
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> 

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Re: [time-nuts] Parallel voltage regulators

[Matt Ettus]

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This may be a bit late in this [strangely contentious] discussion, but
I have to ask why you need to regulate the heater voltage?  If the
voltage varies, the control loops will adjust accordingly.  Unless the
input voltage is higher than some safe range for the heater circuitry.

Matt

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Re: [time-nuts] Parallel voltage regulators

[Magnus Danielson]

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From: Bruce Griffiths <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] Parallel voltage regulators
Date: Thu, 25 Oct 2007 17:42:51 +1300
Message-ID: <[EMAIL PROTECTED]>

> Don Collie wrote:
> > Hi Tom,
> > If you really want to regulate the oven`s supply voltage, my National 
> > Voltage Regulator handbook shows that the LM317T will supply over 2 Amps, 
> > with an input/output differential of between 5, and 12.5 Volts. A single 
> > one 
> > of these should do the job OK.
> > Cheers!,.Don Collie jnr.
> >
> >   
> Never rely on typical specs always use the minimum spec which is 1.5A
> not quite enough.

You want design-margin. Some of that toll will be in less than optimum heating,
some will be in less heating in the first place (compared to upper limit) and
for a power regulating aspect, headroom allows better regulations.

In one design we had to parallel the regulators since the regulator the
designer put in just barely was able to regulate the CPU core voltage.
It worked, but at just rebooted at some vauge point an the memory tests.
What actually happend was that as soon as it started to actually do anything,
the regulator was running at its limit and output voltage dropped as the
current was rising and the voltage supervision pulled the RESET.

That's what you get from reading the typical reading on the CPU current and
match that with the maximum rating of the power regulator. A no margin design.
That designer had a few more flaws which was creeping around in that design,
but let's not bring that can of worms open here. :)

The 5A LM338 will be just fine. Infact, you can pull 8A out of it under
certain conditions.

Cheers,
Magnus

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Re: [time-nuts] Parallel voltage regulators

[Magnus Danielson]

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From: Bruce Griffiths <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] Parallel voltage regulators
Date: Thu, 25 Oct 2007 13:51:47 +1300
Message-ID: <[EMAIL PROTECTED]>

> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> Magnus Danielson wrote:
> > It is not that hard to acheive 2 A at 24 V after all. The old uA723 and
> > variants would probably do the trick good enought for you with external
> > transitor(s).
> >
> > I recommend to at least include fold-back for over-current protection, but
> > adding an over-voltage in form of a crow-bar setup isn't too hard either.
> > The point of the crow-bar is to cause fold-back and if that fails, blow the
> > fuse, so include a fuse on the unregulated supply side.
> >
> > Cheers,
> > Magnus
> >   
> Hej Magnus
> 
> Using a 723 correctly configured with a low pass filter on the reference
> is a very low noise regulator solution with its output noise at least
> 20dB lower than that produced by a typical 3 terminal regulator.
> 
> Most of the OEM open frame linear supplies use 723 regulators with
> external (to the 723) series pass transistors.
> These regulators have varying degrees of sophistication, some even use a
> zener plus emitter follower preregulator for the LM723.
> Some foolishly omit bleeder resistors across the reservoir capacitors
> which can lead to damage when making connections after powering the
> supply on and then off as the residual energy stored in the reservoir
> capacitors is more than sufficient to destroy the 723 should the output
> terminals be shorted.

While the 723 isn't the highest degree of sofistication these days, it does
alow for building more or less complete linear regulators. In another hobby of
mine they are in plentiful use and provide stable enought regulation.

Cheers,
Magnus

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[time-nuts] M100.pdf

[Phil Staton]

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John
It's probably still in the upload section
Phil G4FXY

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Re: [time-nuts] STANAG 4430?

[Brooke Clarke]

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Hi Rob:

Thanks, that will help when I get to setting the clock.  But now I'm still 
working the physical layer.  Things like how many wires, what signals are on 
them, where is the 1 PPS and is it turned off if the clock is not set, how to 
handshake and/or request a transfer, etc.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Rob Kimberley wrote:
> Brooke,
> 
> See the attached which I put together for a project some time ago.
> 
> Hope it is useful.
> 
> Cheers
> 
> Rob Kimberley
> 
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Brooke Clarke
> Sent: 25 October 2007 22:16
> To: time-nuts@febo.com
> Subject: [time-nuts] STANAG 4430?
> 
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> Hi:
> 
> I think the Q-1814 uses STANAG 4430 for the Time Of Day interface.  Does
> anyone 
> have a copy they can emial to me?
> http://www.prc68.com/I/O1814.shtml
> 

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Re: [time-nuts] STANAG 4430?

[Rob Kimberley]

Brooke,

See the attached which I put together for a project some time ago.

Hope it is useful.

Cheers

Rob Kimberley

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Brooke Clarke
Sent: 25 October 2007 22:16
To: time-nuts@febo.com
Subject: [time-nuts] STANAG 4430?

); SAEximRunCond expanded to false
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Hi:

I think the Q-1814 uses STANAG 4430 for the Time Of Day interface.  Does
anyone 
have a copy they can emial to me?
http://www.prc68.com/I/O1814.shtml

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam

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HaveQuick Formats.xls
Description: MS-Excel spreadsheet
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[time-nuts] STANAG 4430?

[Brooke Clarke]

); SAEximRunCond expanded to false
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Hi:

I think the Q-1814 uses STANAG 4430 for the Time Of Day interface.  Does anyone 
have a copy they can emial to me?
http://www.prc68.com/I/O1814.shtml

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam

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Re: [time-nuts] M100 manual

[John Day]

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At 04:00 PM 10/25/2007, you wrote:
>); SAEximRunCond expanded to false
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>
>Just to let anyone interested know,
>I've uploaded an M100.pdf to Ko4BB.com.
>
>Phil

Couldn't find it Phil, at least not where the other related manuals are.

John



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[time-nuts] M100 manual

[Phil Staton]

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Just to let anyone interested know,
I've uploaded an M100.pdf to Ko4BB.com.

Phil

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Re: [time-nuts] Re-triggerable Monostable?

[Hal Murray]

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> I'm working on a synth. project which can take either an external
> 10MHz 
>   reference input or use an internal TCXO.  It would be nice if the
> presence (or more importantly, failure) of the external 10MHz ref.
> could  be detected automatically, and signaled to the user.

Are you happy hacking low level software?  (aka firmware)  If so, consider 
one of the tiny micros.

The PIC 12F629 comes in an 8 pin DIP.  It doesn't require any external 
components.  (Maybe a socket.)

It's got an 8 bit prescaler on Timer0.  That would drop 10 MHz down to 
something you could watch with software.

You even have a couple of pins leftover for other hacks.


I think there are similar chips available in SOT-3-6 if space is critical.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] Scopes and 1 PPS signals?

[Brooke Clarke]

); SAEximRunCond expanded to false
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Hi Didier:

When just a diode is used the stretching is only at the bottom of the trailing 
edge and not enough to help.  But when a little capacitance is added it works.

The period is the same as what the SR620 reported, 1/ 32 Hz.  Seems a strange 
number.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Didier Juges wrote:
> Some DSOs (my lowly Tek 210 does) have a peak detect acquisition mode where
> it will analyze the signal at the highest speed of the A/D converter
> regardless of sweep speed and report the min and max for each displayed
> pixel line. Main advantages are 1) to make aliasing obvious and 2) to be
> able to see very narrow pulses at low sweep speed. I can see 20nS wide
> pulses at 1 PPS easily. Of course, the precision of the measurement (if you
> use the period function) is limited to the display resolution, but at least
> you can get in the ballpark. My scope is in that mode all the time, little
> reason not to.
> 
> If you do not have such mode, put a diode (i.e. 1N4148) in series with the
> probe. The diode will charge the input capacitance of the probe, which will
> discharge exponentially in the 10 Mohm resistance and give you something you
> can see. Can't beat that for cost. Add some capacitance in parallel with the
> probe if needed to widen the pulse.
> 
> Didier KO4BB
> 
> 
>>-Original Message-
>>From: [EMAIL PROTECTED] 
>>[mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke
>>Sent: Tuesday, October 23, 2007 6:24 PM
>>To: Discussion of precise time and frequency measurement
>>Subject: Re: [time-nuts] Scopes and 1 PPS signals?
>>
>>Hi Bill:
>>
>>I'm sure that would work, but it's something else that needs 
>>to be done sometime in the future.
>>
>>I checked the pulse coming from the M12+T and it's more like 
>>100 ms wide, probably for this reason.
>>
>>Have Fun,
>>
>>Brooke Clarke
>>http://www.PRC68.com
>>http://www.precisionclock.com
>>http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
>>
>>
>>WB6BNQ wrote:
>>
>>>Hi Brook,
>>>
>>>You could try using a 74123 (or newer variants) 
>>
>>retriggerable one shot 
>>
>>>to extend the pulse width to a level that would allow you 
>>
>>to see it on the scope.
>>
>>>BillWB6BNQ
>>>
>>>Brooke Clarke wrote:
>>>
>>>
>>>
Hi:

While trying to figure out the O-1814 Rb source I found a 1 
>>
>>PPS signal 
>>
that's less than 10 us wide.  But using an HP 54501A DSO 
>>
>>it's almost 
>>
impossible to determine the period.  
http://www.prc68.com/I/O1814.shtml

If the display is 1,000 dots wide:
at 2 us/sq the trace takes up about 4.5 squares or 450 dots, at 200 
us/sq the trace takes up about 0.045 squares or 4 dots but 
>>
>>the second 
>>
pulse is way off screen.  At slower sweep speeds you can't 
>>
>>see the pulse.
>>
Are there scopes that allow the period of a narrow pulse to be 
measured that don't cost an arm and leg?

--
Have Fun,

Brooke Clarke
> 
> 
> 
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Re: [time-nuts] Re-triggerable Monostable?

[Brooke Clarke]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Hi Grant:

Your re-triggerable monostable idea has been implemented and is called a 
"missing pulse detector".

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Grant Hodgson wrote:
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> I'm working on a synth. project which can take either an external 10MHz 
>   reference input or use an internal TCXO.  It would be nice if the 
> presence (or more importantly, failure) of the external 10MHz ref. could 
> be detected automatically, and signaled to the user.
> 
> There are, of course, a number of ways to do this.  One is to use a 
> level detecting circuit; simply AM detect the ext. ref. input and apply 
> to a comparator.  Lots of circuits to do this, no problem - but requires 
> a number of components, unless there is some magic IC that will do it 
> that I'm not aware of - I suppose a dual op-amp is all that's needed, 
> plus a handful of discretes.
> 
> Another option might be to use a re-triggerable monostable, which is 
> constantly looking for the presence of (say) a falling edge every 100nS 
> on the ext. ref. input line.  It would seem that conceptually, this 
> would be the easiest way, possibly using less components.  Does anybody 
> have any favourite circuits for this; or are there any caveats that are 
> not mentioned in the plethora of monostable circuits that are mentioned 
> on the 'web?
> 
> Mnay (older) test equipments have an int/ext switch on the back, with an 
> indicator on the front, but some newer ones detect the ext. ref. and 
> switch automatically. I suppose that's not a problem on a  box, 
> which this synth. is not.
> 
> The output would simply be a high/low digital line, the ext. ref. input 
> will of course be buffered; I can cope with switching the 10MHz signals.
> 
> Any ideas appreciated.
> 
> regards
> 
> Grant
> 
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[time-nuts] Re-triggerable Monostable?

[Grant Hodgson]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

I'm working on a synth. project which can take either an external 10MHz 
  reference input or use an internal TCXO.  It would be nice if the 
presence (or more importantly, failure) of the external 10MHz ref. could 
be detected automatically, and signaled to the user.

There are, of course, a number of ways to do this.  One is to use a 
level detecting circuit; simply AM detect the ext. ref. input and apply 
to a comparator.  Lots of circuits to do this, no problem - but requires 
a number of components, unless there is some magic IC that will do it 
that I'm not aware of - I suppose a dual op-amp is all that's needed, 
plus a handful of discretes.

Another option might be to use a re-triggerable monostable, which is 
constantly looking for the presence of (say) a falling edge every 100nS 
on the ext. ref. input line.  It would seem that conceptually, this 
would be the easiest way, possibly using less components.  Does anybody 
have any favourite circuits for this; or are there any caveats that are 
not mentioned in the plethora of monostable circuits that are mentioned 
on the 'web?

Mnay (older) test equipments have an int/ext switch on the back, with an 
indicator on the front, but some newer ones detect the ext. ref. and 
switch automatically. I suppose that's not a problem on a  box, 
which this synth. is not.

The output would simply be a high/low digital line, the ext. ref. input 
will of course be buffered; I can cope with switching the 10MHz signals.

Any ideas appreciated.

regards

Grant

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[time-nuts] Z3815A connectors

[jsternmd]

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Hi Morris,

I also found the Harting manufacture (USA) for the connectors and was in 
contact with their Tech support trying to get some for Kit Scally.  You can buy 
the female (same as on the Z3815A board) at Arrow Electronics on-line (I found 
out the hard way thinking it was the male) BUT Harting only supplies the male 
as a custom OEM cable.  I asked for pricing for a 1 meter with open end but 
have not heard anything.  I will contact them again on Monday to follow-up and 
let everyone on the list know status.

Jerry
K1JOS


>Message: 2
>Date: Tue, 23 Oct 2007 20:30:34 +1000
>From: "Morris Odell" <[EMAIL PROTECTED]>
>Subject: [time-nuts] Z3815A connectors
>To: 
>Message-ID: <[EMAIL PROTECTED]>
>Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>   reply-type=original
>
>Hi all,
>
>Thanks to a friend's investigative skills, I have found the maker of the 
>unusual coaxial connector block on the HP Z3815A GPSDO. See:
>
>
>
>Has anyone here had any dealings with this manufacturer or have any idea 
>whether sample or on-off quantities are available?
>
>Morris
>
>
>
>
>
>
>--
>
>___
>time-nuts mailing list
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>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>
>End of time-nuts Digest, Vol 39, Issue 39
>*


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Re: [time-nuts] Parallel voltage regulators

[Bruce Griffiths]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Don Collie wrote:
>
>  Hi Bruce,
> I`ve got the National Semiconductor Corporation Voltage Regulator 
> Handbook [1982]. On page 3-3, the leftmost graph shows the LM117/217/317 as 
> having its current limit, with a junction temperature of
> 125 degrees Centigrade, at 2.25 Amps over the input/output differential of 5 
> to 10 Volts.
> The point being, that if you use a higher current regulator, you loose 
> the advantage of
> the regulator`s current limiting, and perhaps, its thermal shutdown 
> protection as well.
> A fuse *might* protect the semi`s down the line, but often it`s the 
> semi`s that fail before the fuse, and the peak current that might flow 
> before the fuse blows might be many times the current limit of the regulator 
> [which is nearly instantaneous], and if so, damaging, so it is wise to run 
> these regulators near their current limit, just as you would set the current 
> limit on a bench supply to just above the working current.
> I find your use of the emotive words "inexperienced",  "gullible", and 
> "cavalier" saddening.
> Wishing you well,Don.
>  
>   

The graphs are only typical, read the actual printed specifications.
You need to be more skeptical and question your assumptions.

If you want a lower current limit regulator use an LM350.
However you have identified one problem in applying 3 terminal
regulators, the rather wide tolerances associated with the current limit
circuitry.

A 723 regulator can be easily designed to have a much narrower spread
for the current limit.

Bruce

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Re: [time-nuts] QCM

[Ulrich Bangert]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Hi Bernd,

as you know I have a look to the AXTAL web pages @  www.axtal.com from
time to time (highly recommended to other members of time nuts too) but
I completely overlooked this product range. Must have been that the term
"Piezo Sensors" seemed not that interesting for me, bu sure there it is!
Will contact you privately in the next days. Thank you for your
response.

Best regards
Ulrich Bangert 

> -Ursprungliche Nachricht-
> Von: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] Im Auftrag von Bernd T-Online
> Gesendet: Donnerstag, 25. Oktober 2007 06:43
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] QCM
> 
> 
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> Hi Ulrich,
> 
> Ulrich Bangert wrote:
> > Has anyone of you personal experience
> > with QCMs (Quarz Crystal Microbalances) and give me a 
> recommendation 
> > on
> > a) what surface coating is suggested if the aim is to measure small
> > amounts of humidity in clean air
> You should use gold coated QCM
> 
> > b) where such crystals may be supplied from in small quantities
> through my company (AXTAL - www.axtal.com)
> 
> > c) or if anyone is aware of a ready to go humidity sensor 
> based on QCM 
> > technology
> There are several test systems on the market, but none of 
> them is really 
> low cost.
> 
> Best regards
> 
> Bernd Neubig
> __
> AXTAL GmbH & Co. KG
> Facility MOS
> Wasemweg 5
> D-74821 Mosbach / Germany
> fon: +49 (6261) 939834
> fax: +49 (6261) 939836
> www.axtal.com
> 
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> and 
> follow the instructions there.
> 


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Re: [time-nuts] QCM

[Neon John]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

On Thu, 25 Oct 2007 11:04:06 +0200, Jeroen Bastemeijer <[EMAIL PROTECTED]>
wrote:

>Dear Ulrich,
>
>You question is not as much off-topic as you might think. It is all 
>about frequency stability and resonators ;-)  In the past I used to work 
>with SAW-devices and micro-balances. We developed our own sensors and 
>electronics. Search for names like Jakoby, Vellekoop, Lubking and my 
>name and you will find the info.

A somewhat related question.  Can a quartz crystal be used as a pressure 
(actually
medium to high vacuum) sensor?  Specifically, over the range of perhaps 1 Torr 
to
1e-6 Torr.  IOW, over about the same range as a thermocouple gauge.

At first blush it would seem a natural application.  Not knowing what the second
blush is :-)

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Vegetarian - Indian word for "poor hunter".


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Re: [time-nuts] QCM

[Jeroen Bastemeijer]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Dear Ulrich,

You question is not as much off-topic as you might think. It is all 
about frequency stability and resonators ;-)  In the past I used to work 
with SAW-devices and micro-balances. We developed our own sensors and 
electronics. Search for names like Jakoby, Vellekoop, Lubking and my 
name and you will find the info.

We even did research on zero temperature TC SAW devices. The TC was not 
exactly zero but very small compared to the state of the art in those 
days. The zero TC was achieved by choosing a certain cut-angle of the 
quartz. Together with some other mechanisms (TC of other parts) this 
resulted in an almost zero TC behaviour.

For measuring small quantities (small mass) SAW is a very good option 
too. The advantage is that the relative permitivity of the substance 
doesn't influence the measurement. The SAW has a area which can be 
exposed but where no electrical signals are present.

For measuring humidity I would suggest to use porous silicon instead of 
a QCM. A QCM will depend on a chemical reactive layer which will change 
over time and probably will be reactive to other components as well. In 
our experiments we never liked those chemical reactive layers as they 
where never reliable enough. Their characteristics were changing all the 
time

73 Jeroen PE1RGE

Ulrich Bangert schreef:
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
>
> Gentlemen,
>
> again my question is a bit OT: Has anyone of you personal experience
> with QCMs (Quarz Crystal Microbalances) and give me a recommendation on 
>
> a) what surface coating is suggested if the aim is to measure small
> amounts of humidity in clean air
>
> b) where such crystals may be supplied from in small quantities
>
> c) or if anyone is aware of a ready to go humidity sensor based on QCM
> technology
>
> Best regards and TIA 
>
> Ulrich Bangert
> www.ulrich-bangert.de
> Ortholzer Weg 1
> 27243 Gross Ippener 
> Germany
>
>
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>
>
>   

-- 
Ing. Jeroen Bastemeijer

Delft University of Technology
Department of Electrical Engineering
Electronic Instrumentation Laboratory
Mekelweg 4, Room 13.090
2628 CD Delft
The Netherlands

Phone: +31.15.27.86542
Fax: +31.15.27.85755
E-mail: [EMAIL PROTECTED]
GPS: Lat N52.2 Lon E4.37157 Alt 46.2m


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Re: [time-nuts] Parallel voltage regulators

[Don Collie]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY


- Original Message - 
From: "Bruce Griffiths" <[EMAIL PROTECTED]>
To: "Don Collie" <[EMAIL PROTECTED]>; "Discussion of precise time and 
frequency measurement" 
Sent: Thursday, October 25, 2007 7:20 PM
Subject: Re: [time-nuts] Parallel voltage regulators


> Don Collie wrote:
>> Bollocs, Bruce! If National say it will do it, you can bet that it will. 
>> An
>> LM338K will do the job too, but in my opinion it`s overkill, and in the
>> event of a short circuit on the output of the regulator the current for 
>> the
>> LM338 will only be limited to [...he gets the book..] 8 Amps 
>> [Typ],
>> as against 2.2 Amp [Typ] for the LM317T. This would probably be too much 
>> for
>> the transformer, rectifiers, and smoothing capacitor, effectively meaning
>> that you would have no current limiting. If the input/output differential
>> was kept in the range of 5 to 10 Volts, while the oven was stabilising, 
>> and
>> the LM317 had an adequate heatsink, it would do the job nicely [and 
>> cheaper
>> too!] Actually, it wouldn`t matter if the oven supply went unregulated 
>> while
>> the temperature was stabilising, because you wouldn`t be using it for
>> measurements during this time anyway - or is that a bit radical!?
>> All the best!,..Don.
>> - Original Message - 
>> From: "Bruce Griffiths" <[EMAIL PROTECTED]>
>> To: "Don Collie" <[EMAIL PROTECTED]>; "Discussion of precise time and
>> frequency measurement" 
>> Sent: Thursday, October 25, 2007 5:42 PM
>> Subject: Re: [time-nuts] Parallel voltage regulators
>>
>>
>>
> Show me where that is actually guaranteed on the datasheet.
> Only the inexperienced and the gullible fall into the trap of assuming
> every regulator (or any other device) will meet its typical specs.
> The designer of this particular regulator actually cautions against this
> cavalier approach to design.
>
> If you worried about the transformer a simple fuse (resettable or
> otherwise) will surely cure that problem.
>
>
> Bruce

 Hi Bruce,
I`ve got the National Semiconductor Corporation Voltage Regulator 
Handbook [1982]. On page 3-3, the leftmost graph shows the LM117/217/317 as 
having its current limit, with a junction temperature of
125 degrees Centigrade, at 2.25 Amps over the input/output differential of 5 
to 10 Volts.
The point being, that if you use a higher current regulator, you loose 
the advantage of
the regulator`s current limiting, and perhaps, its thermal shutdown 
protection as well.
A fuse *might* protect the semi`s down the line, but often it`s the 
semi`s that fail before the fuse, and the peak current that might flow 
before the fuse blows might be many times the current limit of the regulator 
[which is nearly instantaneous], and if so, damaging, so it is wise to run 
these regulators near their current limit, just as you would set the current 
limit on a bench supply to just above the working current.
I find your use of the emotive words "inexperienced",  "gullible", and 
"cavalier" saddening.
Wishing you well,Don.
 


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Re: [time-nuts] Scopes and 1 PPS signals?

[Rob Kimberley]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

>From the info given, the TOD will be a HaveQuick serial time string. Need to
know what version of HaveQuick.

I have some info on an Excel spreadsheet which may help. Will dig it out.

Rob  

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Brooke Clarke
Sent: 25 October 2007 02:54
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Scopes and 1 PPS signals?

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Hi Dave:

The problem is I don't have any documentation on the O-1814.  The label does

not say Frequency Standard or anything else about what it does.  There is a 
very nice Rb source (M-100) inside and front panel connectors labeled "5 MHz

In", "5 Mhz Out" and "10 MHz Out" so this may be a frequency standard.  But 
it's not clear how any of the radios in the GRC-106 Pacer Speak system can
take 
advantage of a reference frequency.  http://www.prc68.com/I/PRC104.shtml#206

I'm beginning to think this is a Time Of Day standard.  There are buttons
for 
"Rvc TOD" and "Send TOD" as well as a lamp labeled "Set Clock".

I was looking for a serial clock stream that would be used to clock in the
TOD 
serial data stream when I found the narrow pulse.

I tried the SR620.  It's  bouncing around a 32 Hz period.

My web host has changed the server that's hosting PRC68.com and I've sort of

been distracted, but will try the diode pulse stretcher.  If you look at the

link above just below the GRC-206 system photo let me know if you see
(new server)
  Starting with the top row:
First VRC-83 Aircraft Radio <- bold title
(or the old server)
GRC-206(V)1 can be fitted with

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Dave Brown wrote:
> ); SAEximRunCond expanded to false
> Errors-To: [EMAIL PROTECTED] RETRY
> 
> But he knows the period already to parts in 10e-9 or better.  His 
> email sez it's a PPS signal ex an Rb source.
> Not much point in trying to measure that with a scope timebase!
> So I still think he wanted to measure the  ~10uS pulse width..
> 
> DaveB, NZ
> 
> - Original Message - 
> From: "Didier Juges" <[EMAIL PROTECTED]>
> To: "'Discussion of precise time and frequency measurement'" 
> 
> Sent: Wednesday, October 24, 2007 5:27 PM
> Subject: Re: [time-nuts] Scopes and 1 PPS signals?
> 
> 
> 
>>); SAEximRunCond expanded to false
>>Errors-To: [EMAIL PROTECTED] RETRY
>>
>>I read this:
>>
>>"But using an HP 54501A DSO it's almost impossible to determine the 
>>period.
>>http://www.prc68.com/I/O1814.shtml";
>>
>>It seems he wanted to measure the period. For once, the thread 
>>actually was
>>about the original question :-)
>>
>>Didier
>>
>>
>>>-Original Message-
>>>From: [EMAIL PROTECTED]
>>>[mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown
>>>Sent: Tuesday, October 23, 2007 11:21 PM
>>>To: Discussion of precise time and frequency measurement
>>>Subject: Re: [time-nuts] Scopes and 1 PPS signals?
>>>
>>>I took Brookes original inquiry to be about measuring the
>>>width of the
>>>nominally 10 uS  wide PPS pulse-in which case anything that
>>>alters the
>>>pulse width is a no-no.  Precise and stable triggering delay to 
>>>place
>>>one of the pulses in the on-screen area is all  that is required.
>>>DaveB, NZ
>>
>>
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>>
>>-- 
>>No virus found in this incoming message.
>>Checked by AVG Free Edition.
>>Version: 7.5.503 / Virus Database: 269.15.6/1086 - Release Date: 
>>22/10/2007 19:57
>>
>>
> 
> 
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