Driver to drive?

[Jon Slaughter]

<snip>
It depends on the fiber (optical rolloff), but the type of cable I'm
thinking you want doesn't actually have a sheath. That also saves you
the labor of having to remove it.
---
Yes, but the sheath/jacket has two important functions: 1. It protects the
fiber from the wood(not sure if this is an issue but I read that oils from
fingers and change the refraction index along with cuts and such). 2. It
helps make a snug fit into the hole. I do not know if fiber will work as
well.


===
I didn't make it clear in my last post, but you should definitely be
using a plastic or acrylic fiber (not a glass fiber). I didn't get
around to completing that thought. Glass fiber will be too much money
anyway.
----

Yes, I think this is what I'm using now. I'm going to head to the hobby
store and hopfully snatch some to work with.

==
I'm also wondering (out loud, I really haven't thought it
through.....) if you might be able to get by with a silicone lens.
You might even be able to prototype these yourself? Google "Liquid
Silicone Lens" and drill down through some of the hits. Although
focusing might suffer on your protoype, I'm wondering if using a clear
silicone would greatly simply prototype assembly -- or whether it
would just be a big ugly mess to clean up?
----

Google doesn't return anything. What I would be looking for is some type of
small cylinder with the same diameter of the fiber optic that is either
somewhat opaque(hopefully help mix the colors and increase the angle) or
maybe clear but has the same properties. Ultimately it can't decrease the
brighness too much though.

========
The company I was thinking about was Banner Engineering.
(No "S". Duh?!) Oh well. Call their engineers, because they make a
lot of stuff that's nowhere to be found on their web sites. Although,
they're likely too pricey to be a practical solution. But maybe they
can steer you to the right folks. I do know they carry all kinds of
fiber. At least they used to a few years back. Good luck.
---


Ok, I'll check them out.

 

[Jasen Betts]

On 2008-10-19, MooseFET <kensmith@rahul.net> wrote:

On Oct 19, 4:50 pm, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-10-18, MooseFET <kensm...@rahul.net> wrote:

The loss of confidence in the election system puts the nation at
risk. If the losing party feels strongly enough that the will of the
people was thwarted and enough people agree, you have the makings of a
failed state.

This is why the voting system needs to be secure, understandable and
spread out over very many people. Many small errors leading to some
noise or bias in the result will be better tolerated than a few big
errors or even suspicion of error or intent.

what's wrong with pen and paper, tick a box.

There really is nothing wrong with a all paper system. The disabled
would need help to use it but this is also true of all of the
mechanical and electronic ones.

yeah, we're doing that here in NZ on the 8th,

To run a paper system you need more people but since it is the future
of the nation I see no problem there. It would also take longer to
get the results to the central location but there is a long time
between the election and the actual taking of the oath for exactly
this reason.

put 20 markers (with anchoring string pre-attached) in the top of each
box of 5000 voting forms.

Yes and make a special version of the purple ink for the fingers.
While you are at it make the ink in the markers a special ink too.

special paper too if needed, having people there who understand the
system watching is the most imporant thing. if there's people from
all sides watching there won't be irregularities.

We could get "Sharpie" or someone to make up special markers. The
plastic body of the marker could be some weird combination of colors
that are only used for elections.

With special ink for the finger marks and the marker and special
markers, owning any of them could be made against the law and declared
to be evidence of the intent to commit election fraud. This would
make things a lot more secure about extra votes being added.

these sorts of laws strike me as inherently bad.

colouring fingers is only needed in societies where the population
does not already have identitiy papers, just check the names of a list
send the lists in for (mechanical) review at the end. investigate any
double-ups.

OTOH if purple fingers are made fashionable it may help voter turn out


what if someone prints 2000 ballot sheets and gets them marked up to
look like real ones. I don't think anyone can sneak 10 extra sheets into the
box while posting their own ballot, so the crook wouls need atleast
200 accomplicies to sneak those fakes past the observers.

To prevent ballot boxes from being tampered with or taken away, people
watching would work nicely.

let each candidate nominate some number of observers for each
polling place. (2 or 3 at any one time may be enough)

As many as 10 people picked at random like jury duty may be needed.

The ballot boxes could be shipped back
to where they are counted on the transit system's buses. On election
day, extra buses run while the polls are open to take people to vote.
When the polls close some of those same buses take the boxes to be
counted. In farming areas, the school buses and the like would be
called into service.

I'm not sure that the volume of paper would justify that.
but it does give 10 observers somwhere to ride, but probably only 2 or
three are needed for that trip.

I'm not sure how counting is done here, but the ballots are not
transferred long distances and the count is usually concluded by
morning of the next day. there are sometimes one or two electorates
that change hands in the following week when the postal votes are
counted.

after counting, the ballots may need to be sent somewhere for archival
but unless the count is contested a high level of security is probably
not needed.

To me, voting by infernal contraption just seems unnatural.

Bye.
Jasen

 

[Juergen Beisert]

Dirk Bruere at NeoPax wrote:

Juergen Beisert wrote:
backon@vms.huji.ac.il wrote:
I'm in clinical research at a large medical school and a technician
who has designed a device for us needs help.

He's working with a FTDI UM245R USB development
module with a Microchip PIC microprocessor to input
ADC data to a Windows XP pc. The PIC chip, after initializing
handshaking with the UM245R, just dumps data to the port.
The USB port is configured as a serial port COM3. It worked OK
on a breadboard circuit, but now in a hard wired circuit, after
registering the USB port, the USB port shows only CTS (clear to send)
and null characters. What could the problem be?

I'm using the FT245BM FIFO. This device has an ugly behaviour. After each
byte you have to check the "FIFO Empty" (TXE#) line. But this line
changes its state about 300...500ns after the last byte was written! If
you check the line immediately after you have written a byte, and its low
(=space left in FIFO) the next byte you write will be lost! You must wait
until this line changes to high and then low again for each byte!

jbe

Thanks for that tip!

The datasheet says the TXE# line will change to high (=FIFO full) for each
byte you write and low again if there is free space in the FIFO. And it
says the FIFO does not accept new bytes until the TXE# line is low. But it
does not say that it will change so late after each write!
Writing 4 bytes to the FIFO takes about 2us to do so (but the datasheet
suggests you can do it in about 200ns, 50ns per byte).

jbe

 

[John Fields]

On Mon, 20 Oct 2008 02:24:08 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:

You're a babe in arms in this discipline.

---
You wish.

I cut my teeth on audio and was designing and building bridge amplifiers
in the early '60's, even before RCA came out with them, as I recall.

The world has moved on John.

---
As have I, while you guys keep struggling to lower THD to limits which
are so far beyond the threshold of audibility that the point of the
exercise becomes ludicrous.

But it's FUN !

Where would you place the threshold (and what harmonic structure) of audible
THD ?

---
It depends:

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GFRC,GFRC:2006-50,GFRC:en&q=harmonic+distortion+threshold+of+audibility

JF

 

[John Fields]

On Mon, 20 Oct 2008 02:24:08 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:

You're a babe in arms in this discipline.

---
You wish.

I cut my teeth on audio and was designing and building bridge amplifiers
in the early '60's, even before RCA came out with them, as I recall.

The world has moved on John.

---
As have I, while you guys keep struggling to lower THD to limits which
are so far beyond the threshold of audibility that the point of the
exercise becomes ludicrous.

But it's FUN !

---
So if it's fun for you and your clique it's OK, but if it's fun for
someone else, like Olivier, then you'll do your damnedest to try to make
him feel stupid instead of offering a helping hand?


JF

 

[John Fields]

On Mon, 20 Oct 2008 02:29:14 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:

As it is, all you seem to be intent on doing is promoting yourself as
some sort of audio Guru who claims to greatness but who refuses to
submit proof.

Suit yourself. Everything I claim does what it does. All you have to do is
buy one and test it yourself.

---
Why buy when I can build?
---

It would cost you LOTS more to build one yourself and you wouldn't replicate the
pcb pattern which can be critical for top performance.

---
Ah, but since you don't hold the keys to the kingdom I might come up
with something even better, just for the fun of kicking your ass.

I wish you every success.

It also has to fit industry standard form factors. A 3u 19" rack is considered big
for a 2kW amplifier for example, must be as lightweight as possible and must have
certain input processing requirements such as anti-clip circuitry, balanced inputs of
course and user selectable high pass filters to name a few.

---
Should an RFQ for something like that cross my desk I'd probably do the
design just to see whether I wanted to bid it or not.

But a 19" rack?

With the hole spacing still in inches too?

My, oh, my, will wonders never cease! ???

JF

 

[Anthony Fremont]

Frank Buss wrote:

James Waldby wrote:

movf mask,w ; (Only if mask is not in w already)
iorwf IND,r ; set bit
btfss updbyte, 5 ; check for set or reset
xorwf IND,r ; reset bit
continue nop

This is dangerous, if an interrupt is generated after the iorwf.

How so?

 

[Eeyore]

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:

Not if the "additional" pole is at a much higher frequency than the
previous pole inherent to the capacitances of a heap of fets driven by
some wimpy resistive source. Increasing the bandwidth of the output
stage - the serious speed problem - by, say, 20:1 has got to help the
overall loop.

Just buffering Ciss helps a ton.

Just sticking a unity-gain buffer, like an LT1010, in front of the
gate helps a lot.

I've used discrete Class A, with AB capability to get that node really slewing.

But then, you may as well use an opamp and close the
local loop.

I just have this feeling there's a snag here somewhere. Can't place it yet, ah maybe
slew rate from negative cut-off back to conduction would cause a small dead band (in
time terms).

Graham

 

[Jon Slaughter]

"Anthony Fremont" <nobody@noplace.net> wrote in message
news:u_KdndP2zK9LHWHVnZ2dnUVZ_uSdnZ2d@supernews.com...

Frank Buss wrote:
James Waldby wrote:

movf mask,w ; (Only if mask is not in w already)
iorwf IND,r ; set bit
btfss updbyte, 5 ; check for set or reset
xorwf IND,r ; reset bit
continue nop

This is dangerous, if an interrupt is generated after the iorwf.

How so?

If an interrupt occurs before the reset then the state might not be properly
defined if the interrupt depends on the data. Turning off interrupts for the
modification will help but writing the bit in one go is best.

 

[Eeyore]

"Michael A. Terrell" wrote:

Eeyore wrote:
"Michael A. Terrell" wrote:
John Fields wrote:
Eeyore wrote:

I've made one decision though. If one outfit wants me it'll be Group
Technical Director.

My advice would be to take the one where you're likely to do the least
damage.

You would think they already have a know it all janitor.

That's a bit low Michael.

its nt as low as the crap you've been spreading in these audio
threads.

I don't do crap, especially not in audio. Do you want some references btw - one
would be from a guy with a PhD and a Chartered Phsysicist, the other from the
Directors of the company who make the best audio to digital and back converters in
the world.

The fact of the matter is that after something of
a drought (partly for health reasons) it's damn monsoon out there right now.
I don't know how I can satisfy both clients who both have very interesting
respectively moderately big and huge projects on right now.

Plus my back's still fucked.

Big deal. I'm sill 100% disabled, and I had a palsy in my good eye
four months ago that left me effectively blind. I still only have
limited use of that eye, after three months of not being able to see out
of it. I have sores on my legs that aren't healing, and I am scheduled
for some surgery to remove something from my right lower eyelid in about
two weeks. It has been growing rather fast, and I have to wait and see
if it will cause more problems. I have tripped, and banged into so many
things while blind that I am too sore to do much of anything.

I have said before that have every sympathy for you. There's hardly anything
practical I can do though.

Graham

 

[Eeyore]

"Michael A. Terrell" wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:

You make those claims and then, conveniently, fail to back them up
because of the restrictions you claim are placed upon you by copyright
and contractual limitations.

Exactly. I'm behaving professionally. Nor do I want to let all the Chinese see
how to do it right.

Fine. Pay me and I'll do something similar for you and you'll own the
copyright.

---
Pay you???

Thanks, that's the best laugh I've had all day!

Well, let's face it, you don't have the necessary skills.

---
Trying to start a pissing contest?

You haven't the skills and experience in this field.

Ain't gonna work.

I'm sure you're very good at other things.

This is what I meant. If you can't stand the heat, quit shoveling on
the burning coal.

I am a true audio expert Michael, John Fields is not. Each to their own.

Graham

 

[Lostgallifreyan]

"Robert Lacoste" <use-contact-at-www-alciom-com-for-email> wrote in
news:48fc29ed$0$849$ba4acef3@news.orange.fr:

[snip]

Why not a PSoC from Cypress ? You can implement a 14 bit ADC in its
analog
configurable blocs, and there are 8-pin devices in the family.

You mean semi-custom ?

We don't have those quantities.

No, the PSoC is a family of user-configurable mixed signal devices.
Somethink like a microcontroller plus an "analog fpga" in the same chip,
and as cheap as the majority of 8-bit micros. WIth the PSoC-Designer
tool you can simply drag & drop blocks like ADC, PGA, filters, etc. Give
it a try...

Nice. I'll look at those, they sound more interesting to me than PIC's and
such.

 

[Eeyore]

miso@sushi.com wrote:

"Phil Allison" <philalli...@tpg.com.au> wrote:
"Damon Hill"

The vexation I experienced with low-level distortion measurements
with the few designs I could measure with a Tektronix set was that
noise predominated the measurements. I'm not an engineer, and
design for low noise to match distortion levels is beyond me...
as is the price of an AP system.

** It can be very useful to have a digital storage scope when measuring THD
residuals.

Most digital scopes have an "averaging" feature, so as long as you have the
time-base locked to the fundamental, the harmonic residual signal will add
to itself as many times as the scope allows while noise and any AC supply
harmonics tend to disappear from the trace as they are not correlated to the
fundamental sine wave.

Nowadays, many folk like to use a PC with a 24/96 sound card and FFT to do a
spectrum analysis - makes harmonics stand out like dogs balls.

But at such low distortion levels, is it worth it?

** Better ask someone like Halcro ( an Aussie manufacturer).

http://www.halcro.com/home.asp

They have been making a fortune selling $40,000 amps with 0.0005 % THD to
New York's fattest & dopiest Jews.

...... Phil

Or just feed the residual to a DSA. While it is interesting to see
what harmonics are present, looking at the residual relative to the
source is probably more useful. For instance, if the residual error
gets large at the crossover, you know where to tweak. The residual
could also get large at the peaks if the output stage is not beefy, or
some current source is out of compliance on large swings.

The crossover area is the critical one and indeed as you say is also the harmonic
element. If it gets nasty near full power, get a bigger amp !

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:
Eeyore wrote:

You're a babe in arms in this discipline.

---
You wish.

I cut my teeth on audio and was designing and building bridge amplifiers
in the early '60's, even before RCA came out with them, as I recall.

The world has moved on John.

---
As have I, while you guys keep struggling to lower THD to limits which
are so far beyond the threshold of audibility that the point of the
exercise becomes ludicrous.

But it's FUN !

Where would you place the threshold (and what harmonic structure) of audible
THD ?

---
It depends:

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GFRC,GFRC:2006-50,GFRC:en&q=harmonic+distortion+threshold+of+audibility

JF

I was interested in YOUR opinion though.

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:
Eeyore wrote:

You're a babe in arms in this discipline.

---
You wish.

I cut my teeth on audio and was designing and building bridge amplifiers
in the early '60's, even before RCA came out with them, as I recall.

The world has moved on John.

---
As have I, while you guys keep struggling to lower THD to limits which
are so far beyond the threshold of audibility that the point of the
exercise becomes ludicrous.

But it's FUN !

---
So if it's fun for you and your clique it's OK, but if it's fun for
someone else, like Olivier, then you'll do your damnedest to try to make
him feel stupid instead of offering a helping hand?

But I have given him a helping hand by recommending the very best stage for the
job. The complementary emitter follower biased into full Class A. More efficient
than his resistive load circuit too.

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:

As it is, all you seem to be intent on doing is promoting yourself as
some sort of audio Guru who claims to greatness but who refuses to
submit proof.

Suit yourself. Everything I claim does what it does. All you have to do is
buy one and test it yourself.

---
Why buy when I can build?
---

It would cost you LOTS more to build one yourself and you wouldn't replicate the
pcb pattern which can be critical for top performance.

---
Ah, but since you don't hold the keys to the kingdom I might come up
with something even better, just for the fun of kicking your ass.

I wish you every success.

It also has to fit industry standard form factors. A 3u 19" rack is considered big
for a 2kW amplifier for example, must be as lightweight as possible and must have
certain input processing requirements such as anti-clip circuitry, balanced inputs of
course and user selectable high pass filters to name a few.

---
Should an RFQ for something like that cross my desk I'd probably do the
design just to see whether I wanted to bid it or not.

But a 19" rack?

With the hole spacing still in inches too?

My, oh, my, will wonders never cease! ???

The inch is included in the metric system via a back door. I think 0.1" is called an 'e'
or somesuch. History has to be accepted.

482.6mm does for me though.

Graham

 

[Eeyore]

bill.sloman@ieee.org wrote:

On 20 okt, 08:33, "Michael A. Terrell" <mike.terr...@earthlink.net
wrote:
John Larkin wrote:

On Sun, 19 Oct 2008 16:56:42 -0700 (PDT), bill.slo...@ieee.org wrote:

On 19 okt, 19:35, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 19 Oct 2008 04:48:07 -0700 (PDT), bill.slo...@ieee.org wrote:
On 15 okt, 13:18, Eeyore <rabbitsfriendsandrelati...@hotmail.com
wrote:
bill.slo...@ieee.org wrote:

snip

I'd be surprised if Bill ever did anything 'useful'.

Mike isn't really equipped to know - like most good technicians, he's
convinced that he knows everything there is to know about the limited
range of stuff he actually got to work on, and doesn't know much about
electronics outside that rather specialised area.

Oh ! The stuff I could tell you about technicians ! Or maybe I'd rather now. Nor
to mention fresh Uni graduates. One of them gave me a chance to perform a real
save of a runaway project and turn it into a commercial success which is why a
guy at a very very high level once in Smiths plc (he was a Concorde regular)
with a PhD and a list of qualifications the length of his arm will never forget
me.

Graham

 

[Anthony Fremont]

UltimatePatriot wrote:

mpm wrote:

Please make your check out to the Democratic National Convention, or
Planned Parenthood.
Or even "Joe the Plumber". Maybe it'll help him with his back-taxes.
Thank you.


Back taxes? You're an idiot. You believe all that bullshit the DP
started? You are one gullible dipshit then.

The guy owes back taxes, makes 40K/year, and isn't even licensed as a
plumber. These aren't some trumped up rumors, they are matters of public
record.

 

[Eeyore]

bill.sloman@ieee.org wrote:

I've though up a low distortion (less than 0.1%) variation on the
Baxandall class D oscillator. Is he going to volunteer to come up with
something better?

Google Hypex Bill. UcD Class D. Considered to be very good AIUI. Philips have the
patent. I might be looking into that next year.

Graham

 

[Eeyore]

JosephKK wrote:

Eeyore wrote:
JosephKK wrote:
Eeyore wrote:
bg wrote:
Tim Wescott wrote

So yea, for reproduction the "vacuum tube sound" probably makes no
sense. But given that the distortion of the amplifier is an integral
part of rock & roll guitar, I think it'll be a while before vacuum tube
amps can really be replaced.

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Most excellent post tim,
I'd like to add that a tube guitar amp is about art, not engineering.

A bit of both. I assisted design a tube / valve guitar amp myself which was very
highly regarded at the time btw. You'll even see them still occasionally on
ebay. There was some technology in there. As ever it was me that had to rewind
the original rather poor prototype output transformer. I never do seem to be
able to get away from magnetics !


I think if there was an alternative, any guitarist would gladly dump these
overpriced and overweight clunkers any day.

Too right and for a while a company in the UK called H-H made SS guitar amps.
They were popular for a while because they suited certain playing styles (esp
jazz / jazz rock) but they faded away.

My fave guitar amp is either the AC30 or the Fender Twin Reverb. Or for *raw*
power a Marshall JPM100.

You should see Mr Knoppler's collection though !


So for live gigs they take a selection of guitar amps, mic them, and
feed the mic's to the big clean PA??

Hurrah ! Someone's got it !

Yes, that's EXACTLY what happens.

Graham

Thank you. A touch overboard in your praise though.

8=D

Well you were the first to 'click' how it's done.

Same principle in the studio too.

Graham