Re: [time-nuts] wtd: WWVB info

[Hal Murray]

kb...@n1k.org said:
> So far there have not been any home brew design radios show up that will
> demodulate and lock to the new data format. There is plenty of info on the
> transmit format. The demodulation approach is not crazy hard. That said,
> there’s still a lot of work to get a receiver running.  

Has anybody looked into a software approach?  What sort of front end would 
you want?


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Re: [time-nuts] wtd: WWVB info

[Scott Newell]

At 05:43 PM 8/4/2015, Donald wrote:

I have been looking into WWVB receivers.

I see that the sources I had purchased from a few years ago are no 
longer available(in the US).


I've bought modules and antennas recently from Germany and the UK:

http://www.pvelectronics.co.uk/index.php?main_page=index&cPath=9

http://www.hkw-elektronik.de/en/products/am-receiver-equipment/receiver-modules/


You can strip the module from an $11 clock, but Walmart currently 
appears to be out of stock:


http://www.walmart.com/ip/Westclox-Atomic-LCD-Alarm-Clock-Black/16617255


--
newell  N5TNL

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Re: [time-nuts] 60Hz line data

[Alexander Pummer]

but for a very long time we get --or better to say got in the past -- 
the correct number of periods of the line frequency, I have two clocks 
side by side -- one driven by the power line the other is  an "atomic  
clock" from Westclox guided by WWVB and the seldom "disagree"  about the 
time

73
KJ6UHN
Alex

On 8/4/2015 5:17 PM, Hal Murray wrote:

b...@iaxs.net said:

Frankly, I'm puzzled by the graphs that relate to the time offset. All
that's available to the observer is the line frequency. Relative time may be
inferred with a cycle counter. How is that counter set to UTC? How can you
tell the difference between time error from some reference point, and cycles
gained or lost in the counting equipment - due to noise and/or computer
interrupt servicing routines?

The counter isn't set to UTC.  The zero point on the vertical offset is
arbitrary.  All you can measure is the drift relative to some arbitrary
point.  I used the start of the data as zero.  That's the same as setting
your wall clock to UTC when you first took it out of the box and plugged it
in.

If you look in the archives, there is a time-lapse movie make with one frame
each minute when the second hand started straight up.


I'm pretty sure my setup isn't gaining or losing many cycles.  Actually, I'm
pretty sure it is picking up an occasional extra cycle because I see them.
10 seconds at 60 Hz is 600 cycles.  If you get an extra count, the frequency
will be off by 0.1 Hz.  Since the normal range is much less than that, a
sample with an extra cycle stands out.  They are infrequent enough that I
look at each one by hand and make a graph like this:
   http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-2012-Jan-26-a-pick.p
ng

I'm using a human filter.  I haven't tried to automate it.






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Re: [time-nuts] HP10811 dual oven

[Pete Lancashire]

Charles

When I made the offer for the unit, I took the chance that it might be, I
saw that the s/n was 3505A02095, the same HP prefix
on my other dead dual oven 10811.

When I got it, my luck won this time, one of the coax cables is tagged 10
MHz and the other EFC.

A bit of background

The modules came from an HP system that was built for generating the master
T1/E1 clock in a central office. Some chassis
had 64 x 2.048 MHz outputs !

https://goo.gl/photos/t8oXfQ3AdQEFiji46

http://www.jackson-labs.com/assets/uploads/main/HP_AppNote.pdf

I chatted with the seller, The system he got took up 2 rack bays, It had
128 ouputs, and  it had a HP 5071A as the primary clock. Later version are
the ones used a GPS receiver.

http://atecorp.com/atecorp/media/pdfs/data-sheets/Agilent-58504A_Manual.pdf

I don't think many people know about the 55400A, they more then likely
didn't build many. I only read about it when this thing came up for sale.
My guess is there will not be a flood of them on the surplus market. And
sadly think of all the 5071A that more then likely ended up in a
E-Waste/Scrap yard.

-pete




















On Tue, Aug 4, 2015 at 2:24 PM, Charles Steinmetz 
wrote:

> Pete wrote:
>
> I have a HP / Symmetricom unit that has a dual oven 10811 that was part of
>> a telecom master clock distribution system that was only meant to run in a
>> controlled environment.
>>
>
> I'm not 100% positive, but I believe the OCXO in your photos is not an HP
> 10811, but rather the Symmetricom version, which uses a 5MHz crystal and a
> frequency doubler.  I bought a 58503 that the seller guaranteed had a
> 10811, but it turned out to have the Symmetricom oscillator instead.  When
> I pointed this out, the seller offered to refund me the price of a DO
> 10811, which I accepted.  Just for curiosity's sake, I ran the 58503 as it
> was, and after a time it settled into being one of my most stable OCXOs --
> better than all of my 10811s.
>
> Best regards,
>
> Charles
>
>
>
>
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Re: [time-nuts] wtd: WWVB info

[Bob Camp]

Hi

Quick summary:

WWVB changed the format of their transmissions. They now have a phase 
modulation 
component in the signal. That *eventually* will let people make a better chip 
to demodulate
the time info string (and to get more info out of it). So far the new chips 
have not been spotted
for sale to “normal people”.

The older AM chips still work (as do the clocks and watches). Most outfits have 
(apparently) cut
back on the older chips. One might guess they don’t want the inventory when the 
new ones hit the 
market. 

The phase modulation did a number on the old phase tracking “frequency 
standard” receivers. There
are posts in the archives describing work arounds for these devices. 

So far there have not been any home brew design radios show up that will 
demodulate and lock to 
the new data format. There is plenty of info on the transmit format. The 
demodulation approach is 
not crazy hard. That said, there’s still a lot of work to get a receiver 
running. 

One offshoot of the whole switchover is that the people who *were* selling 
antennas pre-made for 
WWVB seem to have dropped stock just like the chip guys. That sort of drives 
you to both home 
brew an antenna and a receiver at the same time. 

Much of this is just the nature of “so many projects / so little time”. Some of 
it is the very normal 
“let’s see what the chip does” wait and see.

Bob

> On Aug 4, 2015, at 6:43 PM, Donald  wrote:
> 
> I have been looking into WWVB receivers.
> 
> I see that the sources I had purchased from a few years ago are no longer 
> available(in the US).
> 
> I see that the format of the WWVB signal has changed a little as well.
> 
> Has NIST done something to not allow chip manufactures to make new 
> chips/modules ?
> Is there any reason why we (in the US) are not allowed to buy these 
> chips/modules any longer ?
> I did get a WWVB receiver out of the UK recently.
> 
> Does anyone have a schematic for building a simple WWVB receiver ?
> 
> Any information would be grateful.
> 
> - Don
> 
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Re: [time-nuts] wtd: WWVB info

[paul swed]

Don nothing magical. Simply no market.
Regards
Paul
WB8TSL

On Tue, Aug 4, 2015 at 6:43 PM, Donald  wrote:

> I have been looking into WWVB receivers.
>
> I see that the sources I had purchased from a few years ago are no longer
> available(in the US).
>
> I see that the format of the WWVB signal has changed a little as well.
>
> Has NIST done something to not allow chip manufactures to make new
> chips/modules ?
> Is there any reason why we (in the US) are not allowed to buy these
> chips/modules any longer ?
> I did get a WWVB receiver out of the UK recently.
>
> Does anyone have a schematic for building a simple WWVB receiver ?
>
> Any information would be grateful.
>
> - Don
>
> ___
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Re: [time-nuts] 60Hz line data

[Hal Murray]

b...@iaxs.net said:
> Frankly, I'm puzzled by the graphs that relate to the time offset. All
> that's available to the observer is the line frequency. Relative time may be
> inferred with a cycle counter. How is that counter set to UTC? How can you
> tell the difference between time error from some reference point, and cycles
> gained or lost in the counting equipment - due to noise and/or computer
> interrupt servicing routines? 

The counter isn't set to UTC.  The zero point on the vertical offset is 
arbitrary.  All you can measure is the drift relative to some arbitrary 
point.  I used the start of the data as zero.  That's the same as setting 
your wall clock to UTC when you first took it out of the box and plugged it 
in.

If you look in the archives, there is a time-lapse movie make with one frame 
each minute when the second hand started straight up.


I'm pretty sure my setup isn't gaining or losing many cycles.  Actually, I'm 
pretty sure it is picking up an occasional extra cycle because I see them.  
10 seconds at 60 Hz is 600 cycles.  If you get an extra count, the frequency 
will be off by 0.1 Hz.  Since the normal range is much less than that, a 
sample with an extra cycle stands out.  They are infrequent enough that I 
look at each one by hand and make a graph like this:
  http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-2012-Jan-26-a-pick.p
ng

I'm using a human filter.  I haven't tried to automate it.




-- 
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Re: [time-nuts] HP10811 dual oven

[Charles Steinmetz]

Pete wrote:


I have a HP / Symmetricom unit that has a dual oven 10811 that was part of
a telecom master clock distribution system that was only meant to run in a
controlled environment.


I'm not 100% positive, but I believe the OCXO in your photos is not 
an HP 10811, but rather the Symmetricom version, which uses a 5MHz 
crystal and a frequency doubler.  I bought a 58503 that the seller 
guaranteed had a 10811, but it turned out to have the Symmetricom 
oscillator instead.  When I pointed this out, the seller offered to 
refund me the price of a DO 10811, which I accepted.  Just for 
curiosity's sake, I ran the 58503 as it was, and after a time it 
settled into being one of my most stable OCXOs -- better than all of my 10811s.


Best regards,

Charles



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[time-nuts] wtd: WWVB info

[Donald]

I have been looking into WWVB receivers.

I see that the sources I had purchased from a few years ago are no 
longer available(in the US).


I see that the format of the WWVB signal has changed a little as well.

Has NIST done something to not allow chip manufactures to make new 
chips/modules ?
Is there any reason why we (in the US) are not allowed to buy these 
chips/modules any longer ?

I did get a WWVB receiver out of the UK recently.

Does anyone have a schematic for building a simple WWVB receiver ?

Any information would be grateful.

- Don

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[time-nuts] 58503A stats

[Alan Ambrose]

Hi,

Here is a screen capture from excellent Ulrich's Z38XX program:

https://www.dropbox.com/s/6p5dr8apsftrckf/Z38XX-1.JPG?dl=0

This is the first time that I've seen this output and I have a couple of 
questions. I should explain that the antenna is fairly well situated in London 
UK with a good view south with no obstacles and ~5m above and away from any 
other roofs. There are 3 small skyscrapers about ½ mile distance at 140° 
azimuth and 15° elevation. There are however obstructions about 4m away to the 
NW & SW (around 240° and 330°) limiting the view to 45° elevation. The device 
is a 58503A (it might be some dodgy far east 're-manufacture') with tracking of 
max 6 active sats. I've set the elevation mask temporarily to 0° to get the 
fullest map - as you can see that doesn't make much difference.

+ I was surprised to see such a noisy EFC signal - I assumed that the EFC 
changed v. gradually on a slow loop - maybe with temperature and aging. However 
there's a lot of high frequency crud there which I don't understand.
+ The 'holdover uncertainty predict' seems to go on a daily loop along with the 
EFC from 1.5 to 2.4us - presumably with temperature? If that's normal behaviour 
it suggests that the DOCXO isn't that well thermally managed?
+ The holdover uncertainty and the 1 pps variance don't relate at all to the 
occasional drop down to 3 sats. So some other effect is at work here - is this 
just ionosphere and general short term GPS inaccuracy only?
+ The time stability measures are not credible in their relentless plunge 
downward?
+ The azimuth/elevation chart looks about right except for the view to the 
south (say 150° to 220°) where I would expect at least as good as the view to 
the east - say by another 20° of elevation? (There's a point at 0/0 which I'm 
sure is an artefact caused by temporary '---' characters in the El/Az output of 
the device.) I don't have many ideas on this as the view is dead good. Any 
thoughts?
+ There's v little below 20° elevation - I think the view is clear though for 
most of the S azimuth down to ~0°. Is this simply because the device tends to 
ignore low elevation sats in its tracking because it has better ones to play 
with?

Would all you greybeards out there give the benefit of your hard-won experience 
and/or maybe there are other people's charts to compare with?
Regards, Alan



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Re: [time-nuts] HP10811 dual oven

[paul swed]

Pete
Always the interesting tid bits.
Thats the same double oven in the HP Z3801
I have one that went nuts. What a gooey mess. I set the whole thing on the
shelf as a someday project. The Z3801 actually has something besides that
as an issue.
Regards
Paul.
WB8TSL

On Tue, Aug 4, 2015 at 12:47 PM, Pete Lancashire 
wrote:

> Bob/TNuts ..
>
> I have a HP / Symmetricom unit that has a dual oven 10811 that was part of
> a telecom master clock distribution system that was only meant to run in a
> controlled environment.
>
> https://goo.gl/photos/xpfnxRegRyuykLSy5
>
> Just another data point
>
> -pete
>
>
>
> On Sun, Aug 2, 2015 at 3:26 PM, Bob Camp  wrote:
>
> > Hi
> >
> > The “external” heater on the Z3801 OCXO is only needed if you are
> > regularly running below -20C in your environment. Other than
> > the alarm signal, there is no harm in letting it simply shut off forever.
> >
> > Bob
> >
> > > On Aug 2, 2015, at 8:56 AM, tim...@timeok.it wrote:
> > >
> > >
> > > Hi,
> > > I have seen, but I do not remember where, someone have rebuilt the
> > external oven controller to complete a stand alone OCXO removed from an
> > HPZ3801A.
> > > Can you hep me to find the document?
> > >
> > > Luciano
> > > timeok
> > >
> > >
> > > Message sent via Atmail Open - http://atmail.org/
> > > ___
> > > 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] HP10811 dual oven

[WarrenS via time-nuts]

Mark Posted

I laid out a through-hole version of Warren's board in Eagle
and had OSHPARK fab up three of them.
I sent one to Warren and am using the other two.
The one mod I made was to use a single darlington TO-220 instead
of the two transistor stage that Warren used.
They seem to work quite well.


I tested Mark's through-hole PC board Dual oven controller and
it worked very well and was well laid out.**(see attached)**
The only changes I made to Mark's PCB where:
R1(Temperature Adj) ~ 35K  and R4 = 1K

Dan Kemppainen also laid out a nice looking, very small surface
mount dual oven control board, but I was not able to test it.

This outer oven controller is able to hold the inner oven's temperature
to within 0.1C over normal room temperature variations,
The effect is the HP10811's frequency change due to temperature variation
(aka temp coeff) is reduced by more than 60 to 1,
from 6e-11/C to under 1e-12 /C




As has pointed out in response to the above nut posting,
if the osc is already being disciplined at shorter time constants,
then the improvement is not nearly as great, and may not be helpful.
The big improvement is seen when the osc is in holdover or running
open loop or running with a very long disciplined time constants >1000
seconds.

The reason I designed the linear dual oven controller to run on
15V power is that unlike the standard HP10811, the dual
oven 10811's inner oven can run at 15V, So a single 15 volt PS
followed by a 12V regulator makes it a single supply design.

Is a outer oven needed? Yes, but only if you are a freq nut.
Note that adding an outer oven is generally easier to do than
burying the osc in a pool of underground mercury or most of the
other nut things that have been suggested in the past to reduce the
effect of temperature variation.


ws

*
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[time-nuts] eLORAN test 6 Aug. Both Dana In. and wildwood nj

[paul swed]

The Wildwood, NJ Transmitter will be on air from 0900 (EDT) 06 August until
1800 (EDT) 07 August. Wildwood will be broadcasting as 8970 Master and
Secondary.

The Dana, IN transmitter will also be on air intermittently during this
time period. Dana will be broadcasting as 9960 Master and possibly other
rates and stations as well.


So at least 2 GRIs and at different locations. That will make it pretty
interesting.

Regards

Paul

WB8TSL
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Re: [time-nuts] 58503A stats

[Alan Ambrose]

p.s. here's the view south taken from about 2m below the antenna:

https://www.dropbox.com/s/zejod2sfi4iogq1/IMG_460371644.JPG?dl=0

Alan

From: Alan Ambrose
Sent: 04 August 2015 9:50 AM
To: 'time-nuts@febo.com' 
Subject: 58503A stats

Hi,

Here is a screen capture from excellent Ulrich's Z38XX program:

https://www.dropbox.com/s/6p5dr8apsftrckf/Z38XX-1.JPG?dl=0

This is the first time that I've seen this output and I have a couple of 
questions. I should explain that the antenna is fairly well situated in London 
UK with a good view south with no obstacles and ~5m above and away from any 
other roofs. There are 3 small skyscrapers about ½ mile distance at 140° 
azimuth and 15° elevation. There are however obstructions about 4m away to the 
NW & SW (around 240° and 330°) limiting the view to 45° elevation. The device 
is a 58503A (it might be some dodgy far east 're-manufacture') with tracking of 
max 6 active sats. I've set the elevation mask temporarily to 0° to get the 
fullest map - as you can see that doesn't make much difference.

+ I was surprised to see such a noisy EFC signal - I assumed that the EFC 
changed v. gradually on a slow loop - maybe with temperature and aging. However 
there's a lot of high frequency crud there which I don't understand.
+ The 'holdover uncertainty predict' seems to go on a daily loop along with the 
EFC from 1.5 to 2.4us - presumably with temperature? If that's normal behaviour 
it suggests that the DOCXO isn't that well thermally managed?
+ The holdover uncertainty and the 1 pps variance don't relate at all to the 
occasional drop down to 3 sats. So some other effect is at work here - is this 
just ionosphere and general short term GPS inaccuracy only?
+ The time stability measures are not credible in their relentless plunge 
downward?
+ The azimuth/elevation chart looks about right except for the view to the 
south (say 150° to 220°) where I would expect at least as good as the view to 
the east - say by another 20° of elevation? (There's a point at 0/0 which I'm 
sure is an artefact caused by temporary '---' characters in the El/Az output of 
the device.) I don't have many ideas on this as the view is dead good. Any 
thoughts?
+ There's v little below 20° elevation - I think the view is clear though for 
most of the S azimuth down to ~0°. Is this simply because the device tends to 
ignore low elevation sats in its tracking because it has better ones to play 
with?

Would all you greybeards out there give the benefit of your hard-won experience 
and/or maybe there are other people's charts to compare with?

Regards, Alan



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Re: [time-nuts] HP10811 dual oven

[Pete Lancashire]

Bob/TNuts ..

I have a HP / Symmetricom unit that has a dual oven 10811 that was part of
a telecom master clock distribution system that was only meant to run in a
controlled environment.

https://goo.gl/photos/xpfnxRegRyuykLSy5

Just another data point

-pete



On Sun, Aug 2, 2015 at 3:26 PM, Bob Camp  wrote:

> Hi
>
> The “external” heater on the Z3801 OCXO is only needed if you are
> regularly running below -20C in your environment. Other than
> the alarm signal, there is no harm in letting it simply shut off forever.
>
> Bob
>
> > On Aug 2, 2015, at 8:56 AM, tim...@timeok.it wrote:
> >
> >
> > Hi,
> > I have seen, but I do not remember where, someone have rebuilt the
> external oven controller to complete a stand alone OCXO removed from an
> HPZ3801A.
> > Can you hep me to find the document?
> >
> > Luciano
> > timeok
> >
> >
> > Message sent via Atmail Open - http://atmail.org/
> > ___
> > 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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> To unsubscribe, go to
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> and follow the instructions there.
>
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[time-nuts] Looking for manual Micrologic ML200

[Ludwig Puller]

Subject: looking for manual Micrologic ML200

Hi all, I found a ML 200 loran C receiver and would like to put it on work.
Can anybody supply me with a manual?
Any help is very appreciated
Regards
Ludwig
oe1lpw

---
Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft.
https://www.avast.com/antivirus

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Re: [time-nuts] HP10811 dual oven

[billriches]

Hi Dan,  

I would appreciate it also. Thank you.

73, 

Bill, WA2DVU
Cape May

-Original Message-
From: time-nuts [mailto:time-nuts-bounces+bill.riches=verizon@febo.com] On 
Behalf Of Alexander Pummer
Sent: Monday, August 03, 2015 8:14 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP10811 dual oven



Hi Dan,
I would be interested on that document too Thank you in advance
73
KJ6UHN
Alex

On 8/3/2015 12:40 PM, Dan Kemppainen wrote:
> Hi,
>
> If you search the internet, you should come across a design by Warren 
> S. It's basically the same type of oven controller that is used in the 
> internal oven for that oscillator.
>
> I did a surface mount version of his design a while back. I've been 
> running it for quite a while now. IMO it is helping to reduce the 
> thermal drift of the oscillator.
>
> Bob has pointed out in the past that the outer oven was not intended 
> to be active all of the time. This is probably true. That said it 
> seems to help in my setup.
>
> If you are unable to find the documentation, please let me know. I can 
> try to dig it up when I get home.
>
> Dan
>
>
>
>
> On 8/3/2015 12:00 PM, time-nuts-requ...@febo.com wrote:
>>
>> Hi
>>
>> The “external” heater on the Z3801 OCXO is only needed if you are 
>> regularly running below -20C in your environment. Other than the 
>> alarm signal, there is no harm in letting it simply shut off forever.
>>
>> Bob
>>
>>> >On Aug 2, 2015, at 8:56 AM,tim...@timeok.it  wrote:
>>> >
>>> >
>>> >Hi,
>>> >I have seen, but I do not remember where, someone have rebuilt the
>>> external oven controller to complete a stand alone OCXO removed from 
>>> an HPZ3801A.
>>> >Can you hep me to find the document?
>>> >
>>> >Luciano
>>> >timeok
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Re: [time-nuts] Modified Allan Deviation and counter averaging

[Magnus Danielson]

Poul-Henning,

On 08/03/2015 01:07 AM, Poul-Henning Kamp wrote:


In message <55bdb002.8060...@rubidium.dyndns.org>, Magnus Danielson writes:


For true white PM *random* noise you can move your phase samples around,
but you gain nothing by bursting them.


I gain nothing mathematically, but in practical terms it would be
a lot more manageable to record an average of 1000 measurements
once per second, than 1000 measurements every second.


Yes, averaging them in blocks and only send the block result is indeed a 
good thing, as long as we can establish the behavior and avoid or remove 
any biases introduced. Bursting them in itself does not give much gain, 
as the processing needs to be done anyway and even rate works just as 
well. A benefit of a small burstiness is that you can work on beat-notes 
not being multiple of the tau0 you want, say 1 s.


As in any processing, cycle-unwrapping needs to be done, as it would 
waste the benefit.


For random noise, the effect of the burst or indeed aggregate into 
blocks of samples is just the same as doing overlapping processing as 
was done for ADEV in the early 70thies as a first step towards better 
confidence intervals. For white noise, there is no correlation between 
any samples, so you can sample them at random. However, for ADEV the 
point is to analyze this for a particular observation interval, so for 
each measure being squared, the observation interval needs to be 
respected. For the colored noises, there is a correlation between the 
samples, and it is the correlation of the observation interval that main 
filtering mechanism of the ADEV. However, since the underlying source is 
noise, you can use any set of phase-tripplets to add to the accumulated 
variance. The burst or block average, provides such a overlapping 
processing mechanism.


However, for systematic noise such as the counter's first order time 
quantization (thus ignoring any fine-grained variations) will interact 
in different ways with burst-sampling depending on the burst length. 
This is the part we should look at to see how we best achieve a 
reduction of that noise in order to quicker reach the actual signal and 
reference noise.



For any other form of random
noise and for the systematic noise, you alter the total filtering
behavior [...]


Agreed.


I wonder if not the filter properties of the burst average is altered 
compared to an evenly spread block, such that when treated as MDEV 
measures we have a difference. The burst filter-properties should be 
similar to that of PWM over the burst repetition rate.


I just contradicted myself. I will come back to this topic, one has to 
be careful as filter properties will color the result and biases can 
occur. Most of these biases is usually not very useful, but the MDEV 
averaging is, if used correctly.


Cheers,
Magnus
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[time-nuts] HP10811 dual oven

[Mark Sims]

I laid out a through-hole version of Warren's board in Eagle and had OSHPARK 
fab up three of them.  I sent one to Warren and am using the other two.  The 
one mod I made was to use a single darlington TO-220 instead of the two 
transistor stage that Warren used.   They seem to work quite well.

I started another layout to use '723 regulators for the supplies and an 
external EFC voltage generator,  but never got around to finishing it.  
  
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