Driver to drive?

[Fred Bloggs]

Tom Seim wrote:

Fred Bloggs <nospam@nospam.com> wrote in message news:<417AFB5A.2060003@nospam.com>...

Tom Seim wrote:

Since you asked me in such a polite way, I'll tell you. While you were
doing drugs I was involved in top secret national defense projects at
the Hanford Nuclear Reservation after graduating from Oregon State U.
in 1969. I am not a vet and never pretended to be one.

Tom

Right- another boondoggle job in a joke of a facility that has created a
500,000 year toxic wasteland-very unimpressive resume.


Well you better hope were are more competent than you would have us to
believe and dealing with high-level radioactive waste. Otherwise a
whole shit-load of some very nasty stuff is heading downstream your
direction.

Recent developments (last week):

All nuclear fuel has been moved out of the K Basin storage pool.

Successful test of the Vitrification plant using real high-level
radioactive waste.

You idiots screw everything up you get your hands on- no hope at all
except for disaster.


Such exceptional insight: now I have a better idea how a schizophrenic
thinks, and it's kinda scary. Hope you aren't operating a nuke plant,
fredfraud.

I've seen what you wimps call "product"- no insight required, and yes,
be scared- you're a timid little fairy draft dodger so many things do
scare you.

 

[nospam]

Terry Pinnell <terrypinDELETE@THESEdial.pipex.com> wrote:

Out of interest I tried simulating the original (symmetrical) circuit
http://www.electronic-circuits-diagrams.com/motorimages/3.gif
with CircuitMaker. But after an hour or so I'm darned if I can get it
working.

Geees the original circuit shorts out the power supply with the power
transistor base emitter diodes - what did you expect to simulate?

As you have gone to the trouble of drawing it simply drag Q4 to where Q3 is
and Q3 to where Q4 is, the same for Q5 and Q6.

You then have a pair of simple class B complimentary amplifiers driving the
motor in a bridge. Why no one else can see this is how the original circuit
was supposed to be is beyond me.

 

[Rich Grise]

On Mon, 25 Oct 2004 03:02:08 -0400, Spehro Pefhany wrote:

On Mon, 25 Oct 2004 06:30:33 GMT, the renowned xray
notreally@hotmail.invalid> wrote:

On Mon, 25 Oct 2004 01:56:30 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

It takes little
time to pick up the skill and it's a good one to have. Try
asking the counter help at RS to demonstrate soldering a
couple of wires together. They likely have someone there
who can do that for you.

Spehro,

All great comments, and a relief from the off-topic threads (wish I had
your restraint), but this notion about help with soldering from Radio
Shack people might be a bit optimistic.

RS is ok, but in my local one, I'd be surprised if any of the people
have ever soldered anything.

It probably depends on the store. I've actually seen them soldering
things on the counter, in my local RS, once (to make up a patch cable
or something). It's worth asking anyhow. ;-)

I just looked at a couple of sites that claim to tell people how to
solder, and they offer silly (clean the wire with acetone) or outdated
and thus harmful advice (like filing the tip of the soldering iron
first!).

I just had a thought - somebody at the school probably knows somebody

who knows how to solder!

Cheers!
Rich

 

[Paul Burridge]

On Mon, 25 Oct 2004 14:57:39 GMT, Fred Bloggs <nospam@nospam.com>
wrote:

Right- there was a case recently at Walter Reed Army Medical where they
killed a 16yo girl by mistaking an antibiotic for anesthetic and killed
her before the operation even got started. Then the cowardly civil
service doctors were caught falsifying the records to make it look more
like a freak accident- such as the dose of antibiotic administered.
This is the kind of thing the Bush supporters will encourage with their
liability limits. People mean nothing to them- they are very similar to
the AlQaeda terrorists that way-actually worse- because the terrorist
are fighting for ideals and the Bush crowd are fighting for money,
exploitation, and cruel domination.

It's symptomatic of the state's distrust of the people. Electioneering
politicians go on and on about "earning the people's trust" and try to
show they're worthy of it (like hell they are) then they spend the
next 4 years dismantling our basic rights and protections (*ancient*
rights and protections here in the UK) because the truth is *they*
don't trust *us*! UK governments have, over the last 15 years, been
insidiously meddling with the 'right to a fair trial' and the
'presumption of innocence' which have existed here as cornerstones of
law for nearly 800 years. We are clearly moving from a position where
the state had to establish your guilt, to one where *you* have to
prove yourself innocent! Jury trial is being systematically tampered
with even as I write. Make sure the same thing doesn't start to happen
in the US...

--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[Steve]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
newsxcfd.18594$nj.13981@newssvr13.news.prodigy.com...

Hi Steve,

Thanks Tim. So we should go for an R-C circuit with an acceptable limit
on
the slew-rate, and not bother with the ferrite bead at all, do you think?
Sorry for my ignorance - that was the first EMC testing I have been
involved
in, and it is a black magic to me TBH.


As Tim said, anything you put in there that tackles an individual line
and not all lines together is going to come with a slew rate penalty.
Even a lone ferrite bead, unless it goes over the whole bundle. I see
two options here but you'd have to share more about the unit (photo of
this area?).

First, you can LC filter each line in that cable except ground. The LC
cutoff could be high as to not affect slew rates too much but low enough
to muffle the EMI. This would only work well if such filtering can be
located really close to an external metal wall and the board is
thoroughly grounded to chassis.

Then there are common mode chokes. These come in SMT and I have used
them in the past. I believe the brands were Murata (Japan) and Vogt
(Germany). It was a choke with four bifilar (well, I guess it'd be
'quadrofilar') windings through there. It was intended for the ISDN
telephone market and, therefore, quite cheap. With these, all wires must
route through there, including ground and everything. The choke should
reside as close to the outer wall as possible. I'd check Murata, Sumida,
Panasonic and others for common mode chokes for the telecom market. You
could also roll your own but it sounds like that's not your intent.

Regards, Joerg

http://www.analogconsultants.com

Many thanks for your suggestions, Joerg. Actually, the cable is just a
digital audio coax cable that plugs into a socket on the back of the unit.
So there are just two conductors in the cable - signal and ground. The
outside of the coax socket is grounded to the chassis, and the chassis is
grounded to the board. The board is grounded to the chassis via the coax
socket itself which is through-hole soldered to the ground plane of the
board. A fixing screw then connects the ground tag of the coax socket to the
chassis. During the last EMI testing, we did try increasing grounding
between the coax socket and board temporarily in case that was a cause, but
it made no difference to the radiated emissions. The signal line itself is
being driven from a 1:1 pulse transformer for isolation purposes from the
rest of the circuity.

As for the PCB layout itself, luckily we are doing a redesign so it
hopefully will be possible to accomodate whatever is required, whether it is
an LC filter or a choke as you suggest, although we only have about one
quarter/third of one inch square to do it in (double-sided board.)

Steve

 

[Rich Grise]

On Thu, 28 Oct 2004 17:27:44 -0700, terry wrote:

Hi,

Anyone could teach me the following?

1. What is the advantage of using metal capacitors?

They conduct so much better than those dumb wood ones.

2. I also want to know the range of values of metal capacitors.

Depends on how much effort you want to put into it, and what
kind of form factor you're looking for. I suppose you could
build one of multiple-Farad size, if you have a 20,000 sq. foot
warehouse.

Thanks!

Any Time!
Rich

 

[Rich Grise]

On Fri, 29 Oct 2004 05:27:11 -0700, vivek wrote:

Hi All,
I want to make a stable current source of 1nA. I want to use it
as reference current for measuring currents < 1nA. Please give me some
circuit ideas and suggest help available on net.

Use very expensive high-value resistors, and lots and lots of aluminum
foil.

Cheers!
Rich

 

[Frank Miles]

In article <6f015b4c.0410290427.48795b6a@posting.google.com>,
vivek <prabhakar.vivek@gmail.com> wrote:

Hi All,
I want to make a stable current source of 1nA. I want to use it
as reference current for measuring currents < 1nA. Please give me some
circuit ideas and suggest help available on net.
Thanx
Vivek

DC? Pulses? Bandwidth? Voltage compliance? Output impedance? Accuracy?

(We'll probably settle for a good resistor, voltage reference,
and some bootstrapping to boost the Zo and accuracy/compliance a bit).

-f
--

 

[Rich Grise]

On Tue, 26 Oct 2004 14:38:11 +1300, Ken Taylor wrote:

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.10.26.00.51.56.161284@example.net...
On Mon, 25 Oct 2004 11:23:15 -0700, Chris Carlen wrote:

Rich Grise wrote:
[edit]
Rich,

I saw your brief posting the other day about just giving out infinite
credit lines to everyone. I don't claim to know whether it would work
or not, nor do I wish to invest considerable effort analyzing it. I
would be interested to read your essays, just out of curiosity, for a
sense of its plausibility.

I simply wonder why your economic thinking is so divergent from the
"usual" libertarian economic thinking? (Not that having a different
viewpoint is bad of course; actually it's the whole point!)

The quick and dirty answer is that I'm first and foremost a believer
in "Free Will" in its fully idealized form, i.e. The Garden of Eden.
So, so far, it only exists in Imaginationland, that I know of. ;-)

When Free Will is fully realized, money becomes irrelevant, becuase
your will, through your intuition and senses, guides you precisely
to wherever whatever it is you need, is. And whoever's there, who
has it, wants something that you have, but are done with, and you
trade, and both are happier and more complete.

...

Cheers!
Rich

Ah, "Free Will". Reminds me, wasn't "Free Willy" that film about the
Bobbitts?

I thought it was a porno flick with Monica Lewinski.

;-)

 

[John S. Dyson]

In article <ckspf8$rbo$5@blue.rahul.net>,
kensmith@green.rahul.net (Ken Smith) writes:

In article <8oicd.14564$nj.6932@newssvr13.news.prodigy.com>,
Clarence <no@No.com> wrote:

"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:Xzecd.376828$mD.361109@attbi_s02...
Jim Yanik wrote:
Saddam was NO THREAT to the United States, or anybody else.

Especially now, sitting in jail!

Actually now he is a bigger threat.

Remember: the intelligence agencies from ALL OVER THE WORLD were

giving input that Saddam was planning this, planning that, etc. We
really need a stronger, more effective CIA (fix the problems -- whatever
is needed), but alas, Clinton worked to weaken the CIA... The long,
horrible, disarming history since the middle 1970's is (partially) yet
another disgusting legacy item from left wing over-reaction against Nixon's
abuses. Geesh, stealing/destroying information from opposition political
headquarters is now a regular Democrat activity... Over the last few
weeks, there have been serious and obviously orchestrated abuses by
the Dems against anyone that they appear to hate. The organization
does show an 'Usama' type situation in the Democrat party, where there
is obviously some strategic planning happening at the highest levels,
but the individual implementations have been incompetent WRT public
relations. Too bad that the 'public' that the Dems appeal to do tend
NOT to be informed about these ongoing Democrat abuses. The organization
is too strong to be attributed to hooliganism, even though it is more
likely that the Dems be like that -- but it is clear that there have
been attacks that were orchestrated at the highest levels, including
even the go-ahead being given by Kerry himself.

Depending upon Putin and even the UK for intelligence info shows the
sad state of affairs in US intelligence. Even if there were a few
data items that might have claimed that Saddam wasn't a threat, the
whole problem is: "WHICH INTELLIGENCE ITEM IS CORRECT, WHICH INTELLIGENCE
ITEM IS INCORRECT." In hindsight, the decision is much easier.

In all cases, it is clear that both the GOPers and Dems believed that
Saddam was a threat (in one way or another), and given that -- there is
no really serious political fault EXCEPT for the longer term, strategic
weakening of the CIA (and other intelligence agencies.)

John

 

[Rich Grise]

On Fri, 29 Oct 2004 01:56:53 +0000, ChrisGibboGibson wrote:

kensmith wrote:
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
kensmith wrote:
ChrisGibboGibson <chrisgibbogibson@aol.com> wrote:
chickenwing2010 wrote:
I'm investigating how a PFM signal can be converted into PWM signal by
hardware. Any suggestions would be very appreciated.
Sounds like homework but what the hell...
Signal into a monostable, LP filter it, remodulate it to PWM using a
comparator
and triangle waveform.
Or, use a PIC.
Yes, or use a PIC.
I don't know if that was meant as a joke in view of another failed thread
I started tonight, but either way it made me laugh.
Hint:
OBAOL: Me to!

I'm still in the dark.

First I asumed OBAOL was a cryptic message.

It's an abbrev. for "obligatory AOL me-too". Apparently AOL is noted
for people who post nothing but "Me, Too!", to the point that it's
become sort of a running joke out here on the outside. ;-)

Perhaps I need a board full of PICs, a few FPGAs, some exotic VHDL software and
the latest ultra low power, super exotic, resistors in order to decode it.

Not forgetting some Spice software (that never seems to agree with reality).

On thinking about the problem, I'm tending towards, "Demod the PFM, and
use the signal to control a whole nother circuit for PWM".

Cheers!
Rich

 

[Phil Hobbs]

Joel Kolstad wrote:

I think that most people are aware of the standard transforms used to
convert lowpass filter prototypes into highpass filters, bandpass filters,
etc. If you look at the result, it's clear that the bandpass filter, for
instance, is an 'interleaved' lowpass and high pass filter design. That
struck me as more coincidental than anything profound, but I've recently
learned that this interleaving is a more general result and apparently can
be done with many different LC filters. That is, if I have two, say, 3
section filters, I can match up the series and shunt sections in each filter
and interleave the two (shunt sections placed in parallel, series sections
placed in series).

So now I'm curious... how does this actually work? Is the idea just that
each starting filter must be operating at frequencies far enough apart from
one another that at any given frequency the components from one filter are
near-opens for shunt components and near-shorts for series components, so
that the two designs don't interact much? Or is there a more general
mathematical basis for why the interleaving works, and you could
successfully interleave something like a notch filter in the middle of a
bandpass filter?

Thanks,
---Joel Kolstad

(Who'll shortly need to be getting new bookshelves after acquiring copies of
Zverev, Matthei/Young/Jones, etc...)


The lowpass to highpass transformation is a conformal map in complex

frequency. If you transform the transfer function from f into
g=fc**2/f, where fc is the 3 dB frequency, all the factors of f/fc
become factors of gc/g, which is the same as transforming Ls into Cs
and Cs into Ls.

The lowpass to bandpass transformation involves a somewhat more complex
mapping, something like g=f/f_0 - f_0/f, where f_0 is the centre
frequency. The centre of the passband is mapped to dc, and both dc and
infinity are mapped to infinity. Thus a capacitor, whose dc impedance
is infinite, changes into a parallel LC, and an inductor, whose dc
impedance is ideally zero, changes into a series LC. In each section,
you use *the same values as the original lowpass*, and chose the new
element to resonate at f_0.

The reactance of each section now changes twice as fast with frequency,
but you get one image of the passband on each side of f_0, so the full
bandwidth is the same as the lowpass prototype's.

Because the transformation is nonlinear, you can't usefully apply this
transformation to linear phase filters unless they are very narrow-band.

Cheers,

Phil Hobbs

 

[Terry Pinnell]

nospam <nospam@nospam.invalid> wrote:

Terry Pinnell <terrypinDELETE@THESEdial.pipex.com> wrote:

Out of interest I tried simulating the original (symmetrical) circuit
http://www.electronic-circuits-diagrams.com/motorimages/3.gif
with CircuitMaker. But after an hour or so I'm darned if I can get it
working.

Geees the original circuit shorts out the power supply with the power
transistor base emitter diodes - what did you expect to simulate?

As you have gone to the trouble of drawing it simply drag Q4 to where Q3 is
and Q3 to where Q4 is, the same for Q5 and Q6.

You then have a pair of simple class B complimentary amplifiers driving the
motor in a bridge. Why no one else can see this is how the original circuit
was supposed to be is beyond me.

I understand that, but that wasn't the point. The circuit should still

simulate for each of the 4 input conditions.

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Joerg]

Hi Don,

And another millimetre on the regen cap and you are transmitting right
back to the Beeb!


That was exactly the problem with the one-triode solution where there

wasn't any preamp to muffle oscillation. For SSB reception you needed
oscillation and that was kind of ok for others as long as you kept it
precisely tuned. But running off to answer the phone and letting the set
drift would cause a whine in the neighbors receiver if he wanted to
listen to the same station.

Regards, Joerg

http://www.analogconsultants.com

 

[Terry Pinnell]

Rich Grise <rich@example.net> wrote:

This is the circuit configuration known as:
"Blow up four transistors simultaneously." ;-)
(note current path from +9v-Q4E-Q4B-Q3B-Q3E-GND, Q5,6 same)

See my reply to nospam.

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Joerg]

Hi Jim,

Same here... I just don't trust wireless, though I have now designed a
few chips for a major player ;-)


Guilty as well, I have also designed things that I won't use myself

because I just don't like the application. Others I hope I never need
because it would mean that I am in the hospital with some serious
problems. And I bet you don't have any of those scent dispensers in the
house ;-)

WLAN may be ok if it is encrypted well enough so nobody can hack in. But
then I have to trust some software and for me that trust has been shaken
lately. If it was good hardware protection I might use it, occasionally,
when all critical stuff is turned off.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hi Michael,

... On the other hand, a guy who lives about
10 miles from me transfers his WWVB clock from livingroom to near a
bedroom window every once in a while so it will synch.


He might have aluminum backed insulation in the walls like we do. My

clock will not work on any wall facing east (where the transmitter is).
It has to hang on an inner wall facing a large window for a sufficient
path towards east.

One option may be to couple from a ferrite antenna that is mounted outside.

Regards, Joerg

http://www.analogconsultants.com

 

[Phil Hobbs]

Don Pearce wrote:

On Thu, 28 Oct 2004 17:46:14 -0700, John Larkin
jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote:



Superregens are the amazing ones. One triode and a few parts, and you
can listen to the BBC from Louisiana.

John



And another millimetre on the regen cap and you are transmitting right
back to the Beeb!


Yeah, but besides that, they're great. The Vout/Vin characteristic is a

beautiful logarithmic curve over a wide range--the famous rushing sound
is amplified thermal noise! Not bad for one tube!

Terman has a very nice discussion of both linear and logarithmic
superregens in "Radio Engineering". They're linear if the quench
frequency is high enough that the oscillation doesn't start limiting,
and logarithmic for lower quench frequencies.

Cheers,

Phil Hobbs

 

[Pooh Bear]

terry wrote:

Hi,

Anyone could teach me the following?

1. What is the advantage of using metal capacitors?

No such thing as 'metal capacitors'.

Do you mean metal foil as opposed to metallised foil perhaps ?

Or do you mean capacitors in metal cans ?

Or whatever.

2. I also want to know the range of values of metal capacitors.

Answer question 1 and we may be able to help.


Graham

 

[Jonathan Kirwan]

On 29 Oct 2004 11:31:14 -0700, Winfield Hill <Winfield_member@newsguy.com>
wrote:

To achieve the 0.1pA range it used a 5G-ohm resistor, teflon standoffs,
etc. Should anyone like to see that design, I can email a .pdf file.

500uV across it? Yes, I'd like to see the design.

Thanks!

Jon