Driver to drive?

[pedro]

On Wed, 15 Mar 2017 02:22:41 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:

When you pay out the ass for healthcare the way we do in America you'd
think they'd at least have the decency to let you keep a copy of the
endoscope recording.

The DVD was included in the cost for my arthroscopic shoulder surgery
about 4 years ago.

 

[rickman]

On 3/15/2017 8:46 AM, tabbypurr@gmail.com wrote:

On Tuesday, 14 March 2017 23:57:20 UTC, rickman wrote:
On 3/13/2017 3:23 PM, oldschool@tubes.com wrote:
On Mon, 13 Mar 2017 09:27:50 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

Thanks to all who replied. I read that WIkipedia article, which
explained what these things are, (even though that article was like
reading a legal manual).

Wikipedia often is written by those with a certain level of elitism
rather than an interest in explaining topics to all who wish to learn.
It is not uncommon for a technical article to be written at such a high
level that a reader needs much more than just a casual understanding of
the topic.

In my opinion, this is one of the ways Wikipedia has failed.

Surely that beats a dumbed down retardopedia. Some topics just aren't that simple. There's always the simple-wiki articles aimed more at children. Wiki has its problems, but I'm not convinced that is one of them.

I may not be an expert in various areas of electronics and computers,
but I am far from a novice. There are various electronics related pages
on Wikipedia that I can't read without going to the references and
studying. That is ridiculous.

When only the experts in a field can even read and understand an
encyclopedia entry I'm not sure that's any better than a "retardopedia".
It essentially becomes the same thing, a web page that conveys very
little information to very few people.

I think the editors end up being full of themselves trying to be
"expert" or "professional". In the end they become irrelevant.

--

Rick C

 

[rickman]

On 3/15/2017 8:24 AM, amdx wrote:

On 3/14/2017 9:21 PM, Jasen Betts wrote:
On 2017-03-15, rickman <gnuarm@gmail.com> wrote:
On 3/14/2017 8:23 PM, whit3rd wrote:
On Tuesday, March 14, 2017 at 11:31:50 AM UTC-7, rickman wrote:
On 3/13/2017 4:26 AM, oldschool@tubes.com wrote:
I've been looking into buying an Audio Generator (Sine and Square
Wave).
I mainly want this to run thru an amplifier to listen to...

I haven't read all of the posts in this thread, but I see a lot of
confusion of the terms "function generator" and "audio generator".
Audio simply refers to the frequency range of the signal generated
without saying anything about the manner in which it is generated.
But
most signal generators output a sine wave and perhaps a square and
triangle wave.

That's incorrect; most inexpensive signal generators output a square
and
triangle (hey, it only takes two op amps); adding a sinewave is
complicated.
To do a GOOD sinewave, the old HP20x units had matched pairs of
adjustable
capacitors, which are VERY pricey items.

So, the iCL8038 and XR2206 and some other IC generators (which dominate
the market at the low-cost end) distort and/or filter the triangle
wave to make
a "sinewave". The sinewave outputs are dreadfull.

So they *do* produce a sine wave?

curved: yes
a sin(2 pi f t + phi ): no.

Under 1% distortion when tweaked.

I don't think our op would notice.

He wants to do a listening test. You know, with the ears. How many of
us can even hear 0.1% distortion?

--

Rick C

 

[Tim Wescott]

On Wed, 15 Mar 2017 08:25:25 -0700, John Larkin wrote:

The people who have been making radios for close to a century have
probably optimized the design.

Optimized for cost to sales ratio, certainly, but maybe not for the best
performance to size ratio.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

 

On Tue, 14 Mar 2017 22:47:44 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:

On 03/14/2017 09:58 PM, Jim Thompson wrote:
"Procedure" tomorrow (Wednesday) at 11:00AM:

Down the throat with a scope, check out the stomach, then into the
small intestine, use side-looking ultrasound on the end of the probe
(didn't know such a thing existed) to examine the common pancreas/bile
duct, go up it with a wire, then thread a balloon up that wire,
inflate and decimate the stones, then go on up and examine the gall
bladder.

Possible later procedure, after the nauseous, tiredness, yellowness
abates, go in thru an incision and remove the gall bladder.

Such fun >:-}

If I don't show up in a day or too...

...Jim Thompson


The "worst" part about being the type that's drawn to engineering is
that it's usually the innately curious type, the kind that wants to read
descriptions of how things work. Like medical procedures.

The usual result is "Well, I wish I hadn't read that."

I found just the opposite. The things that bothered me the most were
the things they didn't (don't) tell me. The other stuff sounded
pretty bad but was a breeze.

Good luck with the gizzard transplant or whatever! ;-)

 

[Phil Allison]

Bill Bowden wrote:

** Your Q is stupid, ferrite antennas must have the wire wound on the rod.


Well, I can't help it if I'm stupid.

** But you can piss off and stop being a PITA troll.

I was just born that way.

** No excuse for you to go around annoying people.

And I did
assume the wire should be wound around the ferrite rod usually using Litz
wire to reduce the skin effect.

** No way anyone can know what you claim you assumed but did not post.

And you can make up *any damn shit* later.

But there are some eddy current losses in
the ferrite and I was just wondering if you knew how much that woud be?

** That is nothing like your original Q and no question was directed at me.

You do NOT direct questions at posters except to explain what they have posted. All other question are directed to the group.

You are making shit up, moment to moment.

Kindly fuck off.


..... Phil

 

[Phil Allison]

mako...@yahoo.com wrote:

And in the AM broadcast band, the SNR is usually not determined by the
radio but rather by the atmospheric noise and interference form
other stations,,,,

** Providing there is an adequate signal from the antenna carrying the wanted broadcast.

so even though you may build an antenna that puts out more "volts"
it will not be helpful for picking up weaker signals.

** Complete non-sequitur and obviously false.



...... Phil

 

[rickman]

On 3/15/2017 4:06 PM, whit3rd wrote:

On Tuesday, March 14, 2017 at 8:27:11 PM UTC-7, rickman wrote:
On 3/14/2017 9:24 PM, whit3rd wrote:

What is inconvenient, is that one cannot dial the frequency with an analog knob, while
listening for room resonances or speaker-crossover blips. A DDS solution will have to
be programmed to do a sweep, and ...

You mean like this?

http://www.etc.sk/index.php/en/products/auxiliary-equipment/control-panels/item/136-control-panel-for-usb-oscilloscopes.html

It looks good, doesn't it? The Agilent had a knob, that controlled one digit at a time of the
frequency (so it would give you a step on dialing). The multipurpose 'knob' of a DDS
gets so many functions assigned to it... just spend a minute or two in the menus, and
you can attach the knob to the 'frequency' attribute. First, though, just a minute or
two in the menus, and you cn attach it to the 'amplitude' attribute. Before that, of course,
you gotta power the gizmo up and give a few seconds to boot, and squint at a few
menus to make sure it's not simulating heartbeats, 'cuz you want a sinewave.

On a test bench, you want to power ON, adjust volume to see a meter move, or hear the
speakers sound off. Then you check the frequency range, and turn the F dial...
all of which takes four seconds. Total.

Yeah, so? I can't fix my flat tire with a hammer either.

--

Rick C

 

[Phil Allison]

Dave M wrote:

It is much more likely that higher inductance is needed at AM broadcast
frequencies in order to keep the tuning capacitaance at a reasonably low
value ...

** Most AM sets have an antenna coil or tuned transformer for that.

A ferrite or woven frame antenna is tuned directly by the tuning gang.




..... Phil

 

[billbowden]

"Phil Allison" <pallison49@gmail.com> wrote in message
news:fde659de-674b-4ce5-afc4-a21d0ff0bc2c@googlegroups.com...

Bill Bowden wrote:

Which is a better design. Suppose you have a 6 inch length of PVC pipe
with
numerous turns of wire that has an inductance of say 200uH. Now suppose
you
use the same (6 inch) piece of PVC with a ferrite rod in the core with
considerably fewer turns of wire. Which one would capture the most
signal
at the AM Broadcast frequencies (500K to 2 Megs) and poduce the greatest
signal output? Would it be more ferrite, or more wire?


** Your Q is stupid, ferrite antennas must have the wire wound on the rod.

Well, I can't help it if I'm stupid. I was just born that way. And I did
assume the wire should be wound around the ferrite rod usually using Litz
wire to reduce the skin effect. But there are some eddy current losses in
the ferrite and I was just wondering if you knew how much that woud be?

Woven, frame antennas like this were used in compact and portable tube
radios until the arrival of ferrite rods.

https://s-media-cache-ak0.pinimg.com/736x/06/4b/b1/064bb104c1c02a095ae2cdeaf60faaa1.jpg

Their performance was comparable with a ferrite rod antennas of similar
length - the ferrite job having rather higher Q due to using less wire.

Most frame anttennas use "Litz" wire to improve the Q - as did ferrite
equivalents.


FYI

Q = ratio of resistance ( at radio frequencies) to inductance.



.... Phil

 

[Phil Allison]

Tim Wescott wrote:

The people who have been making radios for close to a century have
probably optimized the design.

Optimized for cost to sales ratio, certainly, but maybe not for the best
performance to size ratio.

** The latter is exactly what a ferrite antenna is optimised for.


..... Phil

 

[Phil Allison]

Prickman wrote:

BTW, the coil does not need to be wound literally on the core. I've
seen many antennas that were wound on a cardboard or plastic tube with
the ferrite not tight inside. I can only assume they did that to make
the manufacturing easier.

** Wrong assumption.

If you knew a damn thing about AM radios, you would know that the coil is made *movable* on the rod so it's inductance can be adjusted to peak resonance with the frequency being received.

Normally, you do this at the bottom of the band and use a trimmer cap for the top end. The coil is then held in place with melted wax or similar.



..... Phil

 

[Phil Allison]

tabb...@gmail.com wrote:

http://www.intersil.com/content/dam/intersil/documents/icl8/icl8038.pdf


I doubt it managed 50%, let alone 0.5%.

** See page 20 of the pdf.

You are so full of shit.


It had 3 outputs, sine square & triangle. At some frequencies one output looked more like one of the others should, and the others were just a mess.


** Meaningless bollocks.

Your only area of expertise.



..... Phil

 

[billbowden]

<makolber@yahoo.com> wrote in message
news:02d0a874-f95c-40ef-a5f8-be48fa98a573@googlegroups.com...

So adding a material with mu(rel) of 4.0 will cut the number of turns in
half and increase the output voltage by 2. This doesn't include an
improvement in the resistive losses of the coil. The Q of the coil will
be reduced as the inductance drops linearly, but the resistance goes
down by the square root of the permeability.

--

Rick C

And in the AM broadcast band, the SNR is usually not determined by the
radio but rather by the atmospheric noise and interference form other
stations,,,, so >even though you may build an antenna that puts out more
"volts" it will not be helpful for picking up weaker signals.

M

Yes, that's true. It really doesn't matter what the signal strength is, only
how much additional noise you introduce into the system.

 

[Phil Allison]

tabb...@gmail.com wrote:

It's certainly way off. Domestic valve gear typically runs a couple of
decades before needing a new valve.

** More meaningless bollocks.

Valves have a useful life of only a few thousand hours - less if abused.



..... Phil

 

[billbowden]

"rickman" <gnuarm@gmail.com> wrote in message
newsaanum$upg$1@dont-email.me...

On 3/15/2017 12:18 AM, billbowden wrote:
Which is a better design. Suppose you have a 6 inch length of PVC pipe
with
numerous turns of wire that has an inductance of say 200uH. Now suppose
you
use the same (6 inch) piece of PVC with a ferrite rod in the core with
considerably fewer turns of wire. Which one would capture the most
signal
at the AM Broadcast frequencies (500K to 2 Megs) and poduce the greatest
signal output? Would it be more ferrite, or more wire?

You are asking how the antenna output voltage varies with the mu of the
inductor core if the inductance is held constant by varying the number of
turns of wire.

The signal strength is related to number of turns linearly as well as the
core permeability. I'll use the tilda to indicate proportionality.

E ~ N * mu

Inductance is proportional to the square of the number of turns and the
permeability.

L ~ N^2 * mu

So when a magnetic core is added the number of turns required to maintain
the inductance is reduced by the square root of the relative permeability.

N ~ sqrt(mu(rel))

The impact on the received voltage will be reduced by the square root of
the relative permeability through the turns change, but increased linearly
by the change in mu resulting in an overall increase in received voltage
by the square root of the relative permeability.

So adding a material with mu(rel) of 4.0 will cut the number of turns in
half and increase the output voltage by 2. This doesn't include an
improvement in the resistive losses of the coil. The Q of the coil will
be reduced as the inductance drops linearly, but the resistance goes down
by the square root of the permeability.

--

Rick C

So, I think you are saying adding more ferrite into the core and reducing
turns of wire has some signal level advantage? But considering SNR, it
doesn't much matter?

 

[Phil Allison]

John Larkin wrote:

The people who have been making radios for close to a century have
probably optimized the design.

Optimized for cost to sales ratio, certainly, but maybe not for the best
performance to size ratio.


** The latter is exactly what a ferrite antenna is optimised for.


In the early days of transistor radios, size was limited and gain was
expensive, so it was worth some ferrite to get more RF input power.
Gain is now so cheap that an air core antenna might be OK.

** Really ?

Try posting an idea that is not full of ambiguities.


.... Phil

 

[rickman]

On 3/15/2017 5:01 PM, billbowden wrote:

"rickman" <gnuarm@gmail.com> wrote in message
newsaanum$upg$1@dont-email.me...
On 3/15/2017 12:18 AM, billbowden wrote:
Which is a better design. Suppose you have a 6 inch length of PVC pipe
with
numerous turns of wire that has an inductance of say 200uH. Now suppose
you
use the same (6 inch) piece of PVC with a ferrite rod in the core with
considerably fewer turns of wire. Which one would capture the most
signal
at the AM Broadcast frequencies (500K to 2 Megs) and poduce the greatest
signal output? Would it be more ferrite, or more wire?

You are asking how the antenna output voltage varies with the mu of the
inductor core if the inductance is held constant by varying the number of
turns of wire.

The signal strength is related to number of turns linearly as well as the
core permeability. I'll use the tilda to indicate proportionality.

E ~ N * mu

Inductance is proportional to the square of the number of turns and the
permeability.

L ~ N^2 * mu

So when a magnetic core is added the number of turns required to maintain
the inductance is reduced by the square root of the relative permeability.

N ~ sqrt(mu(rel))

The impact on the received voltage will be reduced by the square root of
the relative permeability through the turns change, but increased linearly
by the change in mu resulting in an overall increase in received voltage
by the square root of the relative permeability.

So adding a material with mu(rel) of 4.0 will cut the number of turns in
half and increase the output voltage by 2. This doesn't include an
improvement in the resistive losses of the coil. The Q of the coil will
be reduced as the inductance drops linearly, but the resistance goes down
by the square root of the permeability.

--

Rick C

So, I think you are saying adding more ferrite into the core and reducing
turns of wire has some signal level advantage? But considering SNR, it
doesn't much matter?

If you are building a coil to a specific inductance, then yes, you get
more signal with a ferrite core but the difference is not a lot.

The issue of SNR depends on many factors. You still need a low noise
first amplifier to raise a small signal from an antenna. The point is
that if you have an adequately large signal from the antenna already, a
lower noise in the amp won't be useful as the noise in the signal will
be much greater. But that depends on the specifics of your signal field
strength, the signal SNR, the effective height of the antenna (how well
it converts the field strength to volts) and the noise level of your
receiver front end. How many of these do you know?

BTW, the coil does not need to be wound literally on the core. I've
seen many antennas that were wound on a cardboard or plastic tube with
the ferrite not tight inside. I can only assume they did that to make
the manufacturing easier.

--

Rick C

 

On Thursday, 16 March 2017 00:42:02 UTC, Phil Allison wrote:

tabby wrote:

http://www.intersil.com/content/dam/intersil/documents/icl8/icl8038.pdf


I doubt it managed 50%, let alone 0.5%.


** See page 20 of the pdf.

Page 20 of a 12 page pdf?
Page 2&3 quote 0.05-1.5% distortion, which may well be true for some of the scale. But twiddle the knobs and it went off the chart.

You are so full of shit.


It had 3 outputs, sine square & triangle. At some frequencies one output looked more like one of the others should, and the others were just a mess.


** Meaningless bollocks.

Your only area of expertise.

Baseless abuse is your area of expertise. You don't even know the facts.


NT

 

On Thursday, 16 March 2017 00:46:26 UTC, Phil Allison wrote:

tabby wrote:



It's certainly way off. Domestic valve gear typically runs a couple of
decades before needing a new valve.


** More meaningless bollocks.

Valves have a useful life of only a few thousand hours - less if abused.

horse crap. I've run them way longer. Those lifetimes applied to early bright emitter valves - they've come a whole long way since then.


NT