Driver to drive?

[Phil Allison]

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.

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

 

[rickman]

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

 

On Wednesday, 15 March 2017 12:10:36 UTC, Martin Brown wrote:

On 14/03/2017 13:58, tabbypurr wrote:
On Tuesday, 14 March 2017 09:22:05 UTC, Martin Brown wrote:

There used to be old school analogue function generator chips that
made a triangle wave and then applied diode shaping to get a
pseudo-sine wave. HP made one design implementation that was
surprisingly good. Intersils 8038 was the poor mans alternative for
DIY.

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


I built one of those decades ago. What a car crash. The wave forms
were hopeless. I don't remember the details to know why, I presume
the problem was the 8038 though.

It was never anything like as good as a Wein bridge sine wave but it was
good for about 0.5% THD if you trimmed it properly. I suspect
manufacturing tolerances made it inconsistent batch to batch.

Cute chip in its day, but that was a long time ago.

I doubt it managed 50%, let alone 0.5%. 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. It was dire, and yes I followed the advised circuit. It might manage 0.5% at some frequency, but as a sig gen it was a real failure. If I ever get the time I'll look at it again one day, it's on a shelf somewhere.


NT

 

On Wednesday, 15 March 2017 00:51:22 UTC, k...@notreal.com wrote:

On Tue, 14 Mar 2017 19:43:52 -0400, rickman <gnuarm@gmail.com> wrote:
On 3/13/2017 2:59 PM, Jasen Betts wrote:
On 2017-03-13, dcaster@krl.org <dcaster@krl.org> wrote:
On Monday, March 13, 2017 at 4:28:39 AM UTC-4, olds...@tubes.com wrote:

I've been looking into buying an Audio Generator (Sine and Square Wave).
snip

Solid state equipment is a lot more reliable than vacuum tube equipment. So you are better off buying something new. Getting a replacement vacuum tube may be nearly impossible.

Electrically, tubes are harder to bust...

No they aren't. Just leave one on for a few weeks and the filament
will go out, if it hasn't busted your wallet on the electric bill.

Weeks? MTBF of 336 hours? You can't aford a tube's filament current?
GMAFB

It's certainly way off. Domestic valve gear typically runs a couple of decades before needing a new valve. TVs weren't as reliable, being expensive goods in their time the valves tended to be pushed harder & the TVs ran hot.


NT

 

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.


NT

 

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

 

[Tom Gardner]

On 15/03/17 02:32, Martin Riddle wrote:

On Tue, 14 Mar 2017 18:58:32 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> 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

Good luck, sounds like fun.
But you got me beat, I plan to schedule Knee surgery in a week or so.

I hope it works out.

If the knee is immobilised afterward, you may be surprised
at how fast and how much the quadriceps shrinks.

It might be worth spending the next week sitting down with
the traditional bag of frozen peas over your ankle, then
slowly and repeatedly straightening your leg.

 

[George Herold]

On Wednesday, March 15, 2017 at 8:10:36 AM UTC-4, Martin Brown wrote:

On 14/03/2017 13:58, tabbypurr@gmail.com wrote:
On Tuesday, 14 March 2017 09:22:05 UTC, Martin Brown wrote:

There used to be old school analogue function generator chips that
made a triangle wave and then applied diode shaping to get a
pseudo-sine wave. HP made one design implementation that was
surprisingly good. Intersils 8038 was the poor mans alternative for
DIY.

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


I built one of those decades ago. What a car crash. The wave forms
were hopeless. I don't remember the details to know why, I presume
the problem was the 8038 though.

It was never anything like as good as a Wein bridge sine wave but it was
good for about 0.5% THD if you trimmed it properly. I suspect
manufacturing tolerances made it inconsistent batch to batch.

Right that's my memory, I could tweak one up and get the 3rd harmonic down
below ~1%.. but not by much.
BTW I've got tubes of ICL8038's if anyone wants to play with some, drop me an
email. (Well US/Canada... shipping costs.)

George H.

Cute chip in its day, but that was a long time ago.

--
Regards,
Martin Brown

 

[dcaster@krl.org]

On Wednesday, March 15, 2017 at 8:43:39 AM UTC-4, tabb...@gmail.com wrote:

It's certainly way off. Domestic valve gear typically runs a couple of decades before needing a new valve. TVs weren't as reliable, being expensive goods in their time the valves tended to be pushed harder & the TVs ran hot.


NT

TV's also had more tubes. So with the same mtbf per tube, the system reliability was much less.

Dan

 

[amdx]

On 3/14/2017 8:58 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

Best of luck Jim.
Mikek

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[Martin Brown]

On 14/03/2017 13:58, tabbypurr@gmail.com wrote:

On Tuesday, 14 March 2017 09:22:05 UTC, Martin Brown wrote:

There used to be old school analogue function generator chips that
made a triangle wave and then applied diode shaping to get a
pseudo-sine wave. HP made one design implementation that was
surprisingly good. Intersils 8038 was the poor mans alternative for
DIY.

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


I built one of those decades ago. What a car crash. The wave forms
were hopeless. I don't remember the details to know why, I presume
the problem was the 8038 though.

It was never anything like as good as a Wein bridge sine wave but it was
good for about 0.5% THD if you trimmed it properly. I suspect
manufacturing tolerances made it inconsistent batch to batch.

Cute chip in its day, but that was a long time ago.

--
Regards,
Martin Brown

 

[amdx]

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.

Mikek

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[John Devereux]

Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> writes:

"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...

Good luck Jim, hope it all goes well.


--

John Devereux

 

On Wednesday, 15 March 2017 14:30:05 UTC, dca...@krl.org wrote:

On Wednesday, March 15, 2017 at 8:43:39 AM UTC-4, tabby wrote:

It's certainly way off. Domestic valve gear typically runs a couple of decades before needing a new valve. TVs weren't as reliable, being expensive goods in their time the valves tended to be pushed harder & the TVs ran hot.

TV's also had more tubes. So with the same mtbf per tube, the system reliability was much less.

again mtbf was not the same. This was common knowledge in the valve tv era.


NT

 

On Wednesday, 15 March 2017 16:37:05 UTC, rickman wrote:

On 3/15/2017 8:46 AM, tabbypurr 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.

I don't recall seeing such pages. There are some idiotic ones, wiki certainly has its problems with wallies thinking they're experts. But for an encyclopaedia I don't know a better one.


NT

 

[Dave M]

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?

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 and because of limited space in a portable or tabletop radio.

Dave M

 

On Wednesday, 15 March 2017 01:58:40 UTC, 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

Good luck with it. I hate stuff like that.


NT

 

[John Larkin]

On Tue, 14 Mar 2017 20:18:27 -0800, "billbowden"
<bperryb@bowdenshobbycircuits.info> 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?

A ferrite rod sucks up and concentrates the H field. More flux passes
through the core than if the same geometry were all air. And it needs
a lot less copper to sample that field, an to make a nice inductance
to resonate.

In your case, use a smaller winding directly on the rod or (harder to
do) fill the entire insides of the tube with ferrite.

The rod inserted into your pipe and winding will increase the flux,
but it's not optimum. The people who have been making radios for close
to a century have probably optimized the design.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Cursitor Doom]

On Tue, 14 Mar 2017 18:58:32 -0700, Jim Thompson wrote:

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

You didn't give those of us in Yurp much time to pass on our wishes, Jim,
so you'll be already under the knife or in recovery by now. Best of luck
on getting better and don't stay away too long now. ;-)

 

[whit3rd]

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.