naa, naa, naa poo poo, I know you are but what am I....

Fri Jan 13, 2012 11:46 pm   

Just getting into the spirit of the thing. Do carry on--it reminds me
to be grateful I'm not in middle school any more.

Cheers

Phil Hobbs

Sat Jan 14, 2012 2:11 am   

George Herold wrote:


The Dutch uncle approach doesn't work, because it's patronizing, which only
increases the irritation level of the participants. A bit of mild and
friendly ridicule, OTOH, has been known to help. We'll see.

I've built a fair amount of spectroscopic apparatus, but haven't done much
actual spectroscopy myself. This looks like a fun one. As an old friend of
mine says, the best gizmos are "simple but devastating."

Cheers

Phil Hobs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Sat Jan 14, 2012 2:20 am   

On Jan 13, 5:46 pm, Phil Hobbs
<pcdhSpamMeSensel...@electrooptical.net> wrote:

Phil, after a while I just stop reading the threads. Sure maybe
there's some bit of electronics still going on and I'll miss
something, but.....

Have you ever done any coherent population trapping?

Here's the latest news letter. (the copy is written by my boss, who
understands it less than I do.)

http://www.teachspin.com/newsletters/TeachSpin_DEC11.pdf

The signals are big.

George H.

Sat Jan 14, 2012 7:16 am   

MOMM-MIE!!! THE LITTLE BOYS ARE BICKERING AGAIN!

In completely unrelated news, I wound a 100kVA transformer the other day.
No big deal...

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Phil Hobbs" <pcdhSpamMeSenseless_at_electrooptical.net> wrote in message
news:4F10B44E.2D6CB525_at_electrooptical.net...

Sat Jan 14, 2012 11:43 am   

Phil Hobbs <pcdhSpamMeSenseless_at_electrooptical.net> wrote:
: Do carry on--it reminds me to be grateful I'm not in middle
: school any more.

My feeling exactly ( tinyurl.com/7dblxyf ).

I have been idly pondering, instead, how to make a Poincare dual
out of the T-coil peaking circuit. You know, swapping I <> U,
C <> L, swapping loops with nodes and so on. The required
mutual coupling makes the straighforward conversion difficult.
I guess I must write the transfer function and try to synthesize
the circuit from scratch.

Regards,
Mikko

Sat Jan 14, 2012 5:40 pm   

On Sat, 14 Jan 2012 00:16:52 -0600, "Tim Williams"
<tmoranwms_at_charter.net> wrote:


Real Men do that at 60 Hz.

John

Sat Jan 14, 2012 7:36 pm   

I was doing something like that recently: swapping voltage for current in
the traditional H bridge. Hint: left pair becomes top pair, series diodes
are required (a MOSFET has an antiparallel diode which conducts in
reverse, whereas current more requires open circuit in reverse), and
instead of dV/dt or peak voltage snubbing, you use dI/dt or peak current
snubbing.

What I haven't quite figured out yet is how to conserve number of
snubbers. For example, in the voltage source H bridge, if you indicate
total supply inductance as inductance between the nearest bypass capacitor
and the bridge supply, this becomes the total supply capacitance attached
of the current source (Norton source, current || cap). In the voltage
source, the series inductance needs to be snubbed with an RCD in parallel
with the bridge supply terminals; it follows that, in the current source,
this capacitance needs to be snubbed with an RLD in series with the bridge
supply terminals.

That's all well and good, but the challenge appears when you include
device parasitics as well. This capacitance resonates with the supply
inductance. Analogously, device inductance is distributed around the
bridge and resonates with the supply capacitance. In the voltage-fed
circuit, you can treat these capacitances with one snubber, because they
are in series. In the current-fed circuit, you can't snub the inductances
because they aren't in parallel and you have to treat them individually.

The reason I bring all this up is, it works if you mutually couple the
inductances. This would be difficult to arrange in practice for my
example, but it's a necessary part of yours. Perhaps your answer lies in
series-parallel combinations of capacitance as the equivalent to a
mutually coupled inductor.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Okkim Atnarivik" <Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote in message
news:jerios$ojh$1_at_epityr.hut.fi...

Sat Jan 14, 2012 7:58 pm   

Tim Williams wrote:


Is oo a big boy now?

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Sat Jan 14, 2012 8:19 pm   

John Larkin <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

100 kVA? That's round-off error where I come from. But seriously, that's a
cool thing to wind by hand.

Sat Jan 14, 2012 8:49 pm   

On Sat, 14 Jan 2012 19:19:25 GMT, Ralph Barone
<address_is_at_invalid.invalid> wrote:


Provide the voltages of the primary and secondary and we'll see.

A quarter crusher coil doesn't count.

Sat Jan 14, 2012 10:07 pm   

On Sat, 14 Jan 2012 13:58:24 -0500, Phil Hobbs
<pcdhSpamMeSenseless_at_electrooptical.net> wrote:



A hero steps down
and notices not his fall
into the abyss.

--
JF

Sun Jan 15, 2012 4:10 am   

Pueblo Dancer <Kachina_at_AllHopiIsLost.org> wrote:

A representative transformer for me is a 500 - 230 kV autotransformer good
for about 400 MVA or so. Now, to be honest, I don't design them or build
them. My speciality is the protection systems that trips them offline when
they fault. It was a bit of culture shock moving from university (a
transformer can fit in your hand) to a utility environment (climb inside
this transformer and take a look).

Sun Jan 15, 2012 4:40 am   

On Sun, 15 Jan 2012 03:10:54 GMT, Ralph Barone
<address_is_at_invalid.invalid> wrote:


I've always been impressed by megawatt and gigawatt systems, by the
sheer terror that must be associated with bringing them up the first
time. Like the first flight of a 747. Big RF things, like megawatt AM
stations, are like that too.

It's a nuisance for me to fill a coffee cup with blown mosfets, but
blowing up a 400 MW transformer is a different league. Not to mention
lights-out for, say, the entire East coast.

John

Sun Jan 15, 2012 7:29 am   

On Sat, 14 Jan 2012 19:40:43 -0800, John Larkin
<jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:


time'. There are methods of checking compliance and performance
without actually producing irreversible damage. Full load becomes
basically a thermal issue, as current and voltage stresses are
partioned.

Mind you, there's always the first hook-up wiring 'proof' in the
field......which is usually when the pretested breakers get their
first reality check. You're familiar with those short interruptions in
the lights?

RL

Sun Jan 15, 2012 8:27 am   

On Sun, 15 Jan 2012 03:10:54 GMT, Ralph Barone
<address_is_at_invalid.invalid> wrote:


Then, it was not, of course, "wound by hand".

Quater crusher coils are huge power wise. The thing is it only lasts
for a few milliseconds.