Re: CO2 Funny

On 28/05/2024 1:54 am, john larkin wrote:

On Tue, 28 May 2024 01:05:18 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
 

On 27/05/2024 9:04 pm, john larkin wrote:

On Mon, 27 May 2024 15:05:14 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
>

On 27/05/2024 4:22 am, Edward Rawde wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:v2uhs7$39s6m$1@dont-email.me...

On 26/05/2024 4:38 am, Edward Rawde wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:v2na16$1nvei$1@dont-email.me...

On 23/05/2024 3:52 am, john larkin wrote:

On Wed, 22 May 2024 18:10:58 +0100, Pomegranate Bastard <pommyB@aol.com> wrote:

>
<snip>
>

It usually takes a while to work out why they did it that way, and it's pretty much essential to spend that time before you start
fiddling with the circuit. That wasn't true of the guy who'd put in the 741. He was very much in the John Larkin "if it sort of
works, ship it" camp.

>
Which of John Larkin's products have you purchased and tested and what improvement
do you think should have been made before it was shipped?

>
Absolutely none of them. The timing gear he sells to the American
National Ignition Facility is based on a 1978 Hewlett Packard scheme,
written up in their journal, and it depends on starting up a 50MHz
free-running oscillator in a very predictable way.

>
Totally wrong, as usual. The NIF timing system is synchronous at
155.52 MHz across over 200 timing modules, about 2000 "clients"
triggered every shot.
>
https://highlandtechnology.com/Product/V880
>
https://www.dropbox.com/scl/fi/74f60yne8cdlr53n1x1la/TUAP069.pdf?rlkey=4lp86ca0ztfuh055qyxtok9lm&dl=0

>
That write-up doesn't mention the 1978 Hewlett-Packard Journal article
which you have talked about here.
>
It's a full bottle on the the 155.52 MHz timing scheme which is spread a
across the whole site, which provides the start signal for your delay
generators, but the individual delays generated don't depend on it at
all (although it presumably provides the reference timing for any
auto-calibration that you do)

 You know nothing about this and are, as usual, all wrong. ALL the
module timing is based on the 155.52 MHz clock, which is generated by
a local PLL that is locked to the OC3 optical data stream.

All the module timing may depend on the 155.52MHz master clock, but the connection between edges on that clock and the signal the module puts out to fire the laser is decidedly indirect.
If you divided up the gaps between the 155.52MHz edges to generate your 1psec accurate laser driving pulses you'd be able to claim a direct connection.
155.52MHz is a bit slow for a master clock in such a system.

Faster oscillators have less jitter, and while synchronising to a
continuously running faster oscillator twice may introduce extra jitter,
the net jitter on the time delay can be quite a bit less.

>
We deliver 1 ps timing resolution and a few ps RMS jitter to clients
across a facility the size of a football stadium.

>
Perhaps, but you clearly don't understand what you are actually doing,
otherwise you wouldn't be claiming that I was totally wrong, or invoking
their optically distributed master clock as if were part of your system.

 Can you see the APC connector and the fiber?
 https://highlandtechnology.com/Product/V880
 The VCXO of the PLL is the shiny cube. It's mounted on tiny
custom-made springs to isolate it from shocks from un-mating the SMB
connectors.
 Here's the PLL
 https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?raw=1
 It uses a Dflop bang-bang ECL phase detector. I sure you don't
approve.

The "circuit diagram" shows U11 as square block labelled ECL/VCO.
That makes it the top level block diagram - a more complete circuit diagram might be more informative, but you can't afford to reveal how cheap and nasty the guts of your board is.

We originally uses a Vectron OC3 optical receiver module. It used a
SAW filter to recover the clock and had very low time shift vs optical
power. But they quit making it as OC3 fell out of fashion so I had to
design a drop-in replacement. I'll use an SFP module if we do this
again.  Do I have to give the awards back?
 https://www.dropbox.com/s/rb0fasr1flvvk51/NIF_Award.jpg?raw=1

Why should you? They are passed out to keep sub-contractors happy.

We recently delivered our third system to NIF, the second generation
beamline amplitude modulators. This helped them achieve over-unity
fusion yield.

>
Not as much as a better designed system would have.
>

I had much the same problem in 1988 and went for a free-running 800MHz
oscillator.
>
It turns out that the first version of John's 50MHz oscillator had a
nasty - if small - sub-harmonic oscillation and he's finally found a
better version.

>
It did not.

>
You recently told Phil Hobbs here that something like it did .. in the
"fast discrete PHEMT one-shot thread".

 Different project, a GHz squegg and not a sub-harmonic oscillation.

Squegging is a sub-harmonic oscillation. It repeats over periods longer than the primary oscillation frequency.

The new oscillator fixes that and has superb jitter vs time open-loop,
so the diversion was well worth it. It's so good that I might do a
cheaper DDG based on the open-loop triggered oscillator.

It's presumably "insanely good" - by which you'd mean that we'd have to be nuts to take you seriously.

"Tell me about that. My triggered 50 MHz colpitts oscillator squegged
at around 4 GHz. Tons of jitter.
>
I designed a new osc using a BUF602 and it's great."
>
Finding that prompted me to find his Murata 5GHz ferrite bead post,
which I'd been kicking myself for not writing into my day-book.
>
I'm sure that you are going to tell us that this referred to a
completely different, much more recent project, but I suspect that it
was recycling the old idea and better test gear showed up an old problem.

 Wrong. It's sad that you are driven by vanity and hatred and not
honest  interest in electronics.

The vanity here is all yours. If you were interested in electronics you wouldn't trying to pass off a block diagram as if it were an explanation of what you were doing.
--
Bill Sloman, Sydney