On Monday, 18 September 2017 06:01:17 UTC+1, Jasen Betts wrote:
> On 2017-09-17, tabbypurr wrote:
> > On Sunday, 17 September 2017 01:01:49 UTC+1, Jasen Betts wrote:
> >> On 2017-09-16, Jasen Betts <jasen@xnet.co.nz> wrote:
> >> > On 2017-09-15, Steve Wilson <no@spam.com> wrote:
> >> >> I wonder if that could be applied to guns and bridges.
> >> >
> >> > Boiled linseed oil is the basis of oil paint, of course it's
> >> > outperfomed "chemical" paints like acrylics and polyurethanes these days.
> >>
> >> I meant to write:
> >>
> >> outperformed BY "chemical" paints
> >
> > More outcheap than outperform.
>
> Really you rate linseed oil over acrylic lacquer and two pack
> polyurethane?
I see you want to start a long time wasting discussion. For the record, linseed oil paint is indeed better suited in some cases than chemical paints, which is a wide range of formulae. Every paint has advantages & downsides. Now enjoy wasting your time.
Reply by ●September 16, 20172017-09-16
On Sunday, 17 September 2017 01:01:49 UTC+1, Jasen Betts wrote:
> On 2017-09-16, Jasen Betts <jasen@xnet.co.nz> wrote:
> > On 2017-09-15, Steve Wilson <no@spam.com> wrote:
>
> >> I wonder if that could be applied to guns and bridges.
> >
> > Boiled linseed oil is the basis of oil paint, of course it's
> > outperfomed "chemical" paints like acrylics and polyurethanes these days.
>
> I meant to write:
>
> outperformed BY "chemical" paints
More outcheap than outperform.
NT
Reply by ●September 16, 20172017-09-16
On 16 Sep 2017 23:49:09 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:
>On 2017-09-16, Jasen Betts <jasen@xnet.co.nz> wrote:
>> On 2017-09-15, Steve Wilson <no@spam.com> wrote:
>
>>> I wonder if that could be applied to guns and bridges.
>>
>> Boiled linseed oil is the basis of oil paint, of course it's
>> outperfomed "chemical" paints like acrylics and polyurethanes these days.
>
>I meant to write:
>
> outperformed BY "chemical" paints
Depends on the application, of course.
Reply by Jasen Betts●September 16, 20172017-09-16
On 2017-09-16, Jasen Betts <jasen@xnet.co.nz> wrote:
> On 2017-09-15, Steve Wilson <no@spam.com> wrote:
>> I wonder if that could be applied to guns and bridges.
>
> Boiled linseed oil is the basis of oil paint, of course it's
> outperfomed "chemical" paints like acrylics and polyurethanes these days.
I meant to write:
outperformed BY "chemical" paints
--
This email has not been checked by half-arsed antivirus software
Reply by Boris Mohar●September 16, 20172017-09-16
On Fri, 15 Sep 2017 05:10:31 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:
>On Friday, September 15, 2017 at 2:28:25 AM UTC-4, jrwal...@gmail.com wrote:
>> On Friday, 15 September 2017 02:43:34 UTC+1, dagmarg...@yahoo.com wrote:
>> > On Thursday, September 14, 2017 at 8:46:36 PM UTC-4, Steve Wilson wrote:
>> > > Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
>> > >
>> > > > Did anybody make iron cannons in that era? AFAIK it was Alfred Krupp in
>> > > > the mid-19th century who figured out how to found steel cannons that
>> > > > didn't explode randomly.
>> > >
>> > > > Cheers
>> > >
>> > > > Phil Hobbs
>> > >
>> > > Apparently, the USS Revenge sank in 1811. The US Navy just recovered an
>> > > iron cannon believed to be from the ship:
>> > >
>> > > http://www.businessinsider.com/the-navy-just-found-cannon-that-they-think-
>> > > was-war-of-1812-ship-2017-6?op=1
>> > >
>> > > The 24-pounders were used in the 1700's and made of cast iron:
>> > >
>> > > https://en.wikipedia.org/wiki/24-pounder_long_gun
>> > >
>> > > Here's a view of hundreds of 1819 24-pounders stockpiled at Fortress Monroe
>> > > in Virginia:
>> > >
>> > > http://moultrie.battlefieldsinmotion.com/Artillery-24-pounder.html
>> > >
>> > > They were iron:
>> > >
>> > > "The bore-diameter for all these iron 24-pounders was established at
>> > > exactly 5.82 inches, and they were to weigh roughly 5,800 pounds apiece."
>> > >
>> > > http://moultrie.battlefieldsinmotion.com/Artillery-24-pounder.html
>> > >
>> > > "The Chinese also mounted over 3,000 bronze and iron cast cannon on the
>> > > Great Wall of China, to defend themselves from the Mongols."
>> > >
>> > > https://en.wikipedia.org/wiki/History_of_cannon
>> > >
>> > > Doesn't say when. Maybe the 1500's
>> >
>> > Nice info / links.
>> >
>> > Cheers,
>> > James Arthur
>>
>> A mixture of iron and bronze cannon was found in the remains of the
>> Mary Rose which sank in 1545 and which was launched in 1511.
>>
>> John
>
>As I recall Hornblower commented on his brass stern and bow chasers,
>but other-wise had iron cannon's.
>
>George H.
Reply by George Herold●September 15, 20172017-09-15
On Friday, September 15, 2017 at 5:54:04 PM UTC-4, eagleso...@gmail.com wrote:
> On Friday, September 15, 2017 at 1:29:31 PM UTC-4, Adrian Tuddenham wrote:
> > <millsscientific@gmail.com> wrote:
> >
> > > Hello:
> > >
> > > I am trying to make a homemade circuit to do underwater detection of old
> > > War 1812 US Navy ship cannons. Magnetometers can be bought, but they
> > > are expensive. So, I am looking at a metal detection type circuit.
> >
> > If the canon are definitely made of iron and not bronze, it sounds as
> > though a scaled-up version of my tram-rail detector might work.
> >
> > It consisted of a long round mild steel bar. At the ends are two short
> > bars at right angles to the long bar, they are machined and fixed so
> > that their exact centres are in close contact with the long bar. The
> > whole assembly looks like a letter 'H' with a very elongated central
> > bar.
> >
> > The long bar is wound with a single layer solenoid for most of its
> > length and energised with a 20 c/s sinewave. The four projecting stubs
> > of the two short bars are wound with detector coils of many turns (I
> > used four 3" tape spools with exactly 2000 turns on each).
> >
> > The two detector coils at one end of the long bar are connected in
> > series opposition; likewise the pair at the other end. This means that
> > their voltages cancel if the flux emerging from the two ends of the
> > short bar is equally shared between them. The residual voltage from
> > each pair of coils is amplified separately and phase-detected by
> > comparison with the 20 c/s signal. Any residual signals are reduced to
> > zero by injecting small correction signals into the amplifiers from a
> > "zeroing" control. Two centre-zero meters connected to the outputs of
> > the detectors show the strength and polarity of the rectified signals.
> >
> > The assembly is moved in a direction at right angles to the long axis of
> > the long bar, with the short bars held horizontally. If it approaches a
> > piece of iron, the reluctance of the flux path on one side of the
> > detector will drop relative to the flux path on the other side, so the
> > detector coils on the approach side will give a stronger signal. As the
> > object passes underneath the assembly, the trailing side will suddenly
> > show a stronger signal. By mounting the meters in a suitable
> > orientation to the long bar, these will give a visual indication of the
> > position of the object.
> >
> > If the object is long (such as a tram rail) and is not lying in line
> > with the long bar, one meter will swing before the other one. The long
> > bar can then be rotated until both meters swing at the same time, then
> > it will be lying parallel to the object, which will indicate the
> > orientation of the object.. By tilting the short bars to 45-degrees
> > from the horizontal, triangulation can be used to estimate the depth the
> > object is buried at. (I mounted a broom handle on the detector at
> > 45-degrees, so dropping the handle to horizontal would make
> > triangulation very straightforward)
> >
> > The dimensions of my tram-rail detector were about 2ft x 1" dia. for the
> > long bar and 6" x 0.5" for each of the short bars. For detecting larger
> > objects at greater distances, those dimensions will probably need to be
> > scaled up.
> >
> > I have found that the detector is sensitive to the Earth's magnetic
> > field, which causes variations in the B-H characteristic of the short
> > bars. The zero settings need to be readjusted for any large changes in
> > the heading of the detector.
> >
> > Hope this helps.
> >
> >
> > --
> > ~ Adrian Tuddenham ~
> > (Remove the ".invalid"s and add ".co.uk" to reply)
> > www.poppyrecords.co.uk
>
> Thanks for the reply;
>
> Complexity is an issue right now
>
> I am going to get a TI evaluation board as a start.
>
> http://www.ti.com/tool/drv425evm
>
> It is $20. It can sense the earth magnetic field I think.
> I will have to tow it case perpendicular to the Earth field
> as shown on a diagram in the reference. Giving a maximum output
> voltage to my electrometer.
There are lots of ways to sense magnetic fields. It's not at all clear
that the part you found is in any way optimal, or close to it.
But play around... move around other big pieces of iron and see
what it looks like. I'd do lots of experiments on land
before I tried something in the water.. Break your problem down
into parts.
George H.
>
> Somehow I need an indicator to help maintain course. Likely
> a gps. Somewhere in my notes I have a Java app that should
> help staying on magnetic west or east.
>
> The iron or magnetic steel will perturb the output as
> I pass by source.
>
> It will be a first step to learn with.
>
> The java app can record location by time. A multimeter recording
> the electrometer by time also, exists as a windows PC program.
Reply by ●September 15, 20172017-09-15
On Friday, September 15, 2017 at 1:29:31 PM UTC-4, Adrian Tuddenham wrote:
> <millsscientific@gmail.com> wrote:
>
> > Hello:
> >
> > I am trying to make a homemade circuit to do underwater detection of old
> > War 1812 US Navy ship cannons. Magnetometers can be bought, but they
> > are expensive. So, I am looking at a metal detection type circuit.
>
> If the canon are definitely made of iron and not bronze, it sounds as
> though a scaled-up version of my tram-rail detector might work.
>
> It consisted of a long round mild steel bar. At the ends are two short
> bars at right angles to the long bar, they are machined and fixed so
> that their exact centres are in close contact with the long bar. The
> whole assembly looks like a letter 'H' with a very elongated central
> bar.
>
> The long bar is wound with a single layer solenoid for most of its
> length and energised with a 20 c/s sinewave. The four projecting stubs
> of the two short bars are wound with detector coils of many turns (I
> used four 3" tape spools with exactly 2000 turns on each).
>
> The two detector coils at one end of the long bar are connected in
> series opposition; likewise the pair at the other end. This means that
> their voltages cancel if the flux emerging from the two ends of the
> short bar is equally shared between them. The residual voltage from
> each pair of coils is amplified separately and phase-detected by
> comparison with the 20 c/s signal. Any residual signals are reduced to
> zero by injecting small correction signals into the amplifiers from a
> "zeroing" control. Two centre-zero meters connected to the outputs of
> the detectors show the strength and polarity of the rectified signals.
>
> The assembly is moved in a direction at right angles to the long axis of
> the long bar, with the short bars held horizontally. If it approaches a
> piece of iron, the reluctance of the flux path on one side of the
> detector will drop relative to the flux path on the other side, so the
> detector coils on the approach side will give a stronger signal. As the
> object passes underneath the assembly, the trailing side will suddenly
> show a stronger signal. By mounting the meters in a suitable
> orientation to the long bar, these will give a visual indication of the
> position of the object.
>
> If the object is long (such as a tram rail) and is not lying in line
> with the long bar, one meter will swing before the other one. The long
> bar can then be rotated until both meters swing at the same time, then
> it will be lying parallel to the object, which will indicate the
> orientation of the object.. By tilting the short bars to 45-degrees
> from the horizontal, triangulation can be used to estimate the depth the
> object is buried at. (I mounted a broom handle on the detector at
> 45-degrees, so dropping the handle to horizontal would make
> triangulation very straightforward)
>
> The dimensions of my tram-rail detector were about 2ft x 1" dia. for the
> long bar and 6" x 0.5" for each of the short bars. For detecting larger
> objects at greater distances, those dimensions will probably need to be
> scaled up.
>
> I have found that the detector is sensitive to the Earth's magnetic
> field, which causes variations in the B-H characteristic of the short
> bars. The zero settings need to be readjusted for any large changes in
> the heading of the detector.
>
> Hope this helps.
>
>
> --
> ~ Adrian Tuddenham ~
> (Remove the ".invalid"s and add ".co.uk" to reply)
> www.poppyrecords.co.uk
Thanks for the reply;
Complexity is an issue right now
I am going to get a TI evaluation board as a start.
http://www.ti.com/tool/drv425evm
It is $20. It can sense the earth magnetic field I think.
I will have to tow it case perpendicular to the Earth field
as shown on a diagram in the reference. Giving a maximum output
voltage to my electrometer.
Somehow I need an indicator to help maintain course. Likely
a gps. Somewhere in my notes I have a Java app that should
help staying on magnetic west or east.
The iron or magnetic steel will perturb the output as
I pass by source.
It will be a first step to learn with.
The java app can record location by time. A multimeter recording
the electrometer by time also, exists as a windows PC program.
Reply by Adrian Tuddenham●September 15, 20172017-09-15
<millsscientific@gmail.com> wrote:
> Hello:
>
> I am trying to make a homemade circuit to do underwater detection of old
> War 1812 US Navy ship cannons. Magnetometers can be bought, but they
> are expensive. So, I am looking at a metal detection type circuit.
If the canon are definitely made of iron and not bronze, it sounds as
though a scaled-up version of my tram-rail detector might work.
It consisted of a long round mild steel bar. At the ends are two short
bars at right angles to the long bar, they are machined and fixed so
that their exact centres are in close contact with the long bar. The
whole assembly looks like a letter 'H' with a very elongated central
bar.
The long bar is wound with a single layer solenoid for most of its
length and energised with a 20 c/s sinewave. The four projecting stubs
of the two short bars are wound with detector coils of many turns (I
used four 3" tape spools with exactly 2000 turns on each).
The two detector coils at one end of the long bar are connected in
series opposition; likewise the pair at the other end. This means that
their voltages cancel if the flux emerging from the two ends of the
short bar is equally shared between them. The residual voltage from
each pair of coils is amplified separately and phase-detected by
comparison with the 20 c/s signal. Any residual signals are reduced to
zero by injecting small correction signals into the amplifiers from a
"zeroing" control. Two centre-zero meters connected to the outputs of
the detectors show the strength and polarity of the rectified signals.
The assembly is moved in a direction at right angles to the long axis of
the long bar, with the short bars held horizontally. If it approaches a
piece of iron, the reluctance of the flux path on one side of the
detector will drop relative to the flux path on the other side, so the
detector coils on the approach side will give a stronger signal. As the
object passes underneath the assembly, the trailing side will suddenly
show a stronger signal. By mounting the meters in a suitable
orientation to the long bar, these will give a visual indication of the
position of the object.
If the object is long (such as a tram rail) and is not lying in line
with the long bar, one meter will swing before the other one. The long
bar can then be rotated until both meters swing at the same time, then
it will be lying parallel to the object, which will indicate the
orientation of the object.. By tilting the short bars to 45-degrees
from the horizontal, triangulation can be used to estimate the depth the
object is buried at. (I mounted a broom handle on the detector at
45-degrees, so dropping the handle to horizontal would make
triangulation very straightforward)
The dimensions of my tram-rail detector were about 2ft x 1" dia. for the
long bar and 6" x 0.5" for each of the short bars. For detecting larger
objects at greater distances, those dimensions will probably need to be
scaled up.
I have found that the detector is sensitive to the Earth's magnetic
field, which causes variations in the B-H characteristic of the short
bars. The zero settings need to be readjusted for any large changes in
the heading of the detector.
Hope this helps.
--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Reply by Adrian Tuddenham●September 15, 20172017-09-15
Steve Wilson <no@spam.com> wrote:
>
> With all this iron around, how did they keep it from rusting?
It really was iron, either wrought or cast. Neither of those rusts
particularly quickly.
> Even today, rust is a major problem. I moved back to Ontario after living
> in the US for 30 years. I was astonished to find how quickly everything
> rusted, often to the point of unusability. Cars, tools, you name it.
They are all steel, which rusts far more quickly than iron.
--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Reply by John Larkin●September 15, 20172017-09-15
On Fri, 15 Sep 2017 06:34:19 -0700 (PDT), eaglesondouglas@gmail.com
wrote:
>On Thursday, September 14, 2017 at 8:32:45 PM UTC-4, John Larkin wrote:
>> On Thu, 14 Sep 2017 14:02:56 -0700 (PDT), eaglesondouglas@gmail.com
>> wrote:
>>
>> >
>> >> >
>> >> > Here I would increase the ac frequency to make a coil Q of the required
>> >> > number, 1 to 10.
>> >>
>> >> Are you trying to sense the metal by having it spoil the Q,
>> >> or shift the frequency? In both case I might want a higher Q.
>> >> >
>> >>
>> >Yes, I am not a engineer kind of guy. But my inclination is to
>> >hope that steel or iron would alter L the coil inductance. Does
>> >this mean technically altering Q?
>>
>> Mostly inductance. Iron will make it go up, brass down.
>>
>> >
>> >From what I read this type of bridge works best at a Q of one
>> >to ten. Is ramping it up to 100 allowed?
>>
>> Likely not possible at audio-type frequencies.
>>
>> >
>> >I have an audio oscillator and wonder if I can just add an audio
>> >amplifier for the power source.
>>
>> You can make an AC bridge, drive it with a good sine wave, listen to
>> the null with amplified headphones, tweak the bridge or the frequency
>> for a deep null.
>>
>> I guess you could use a resonated loop in an AC bridge, too. Might be
>> more sensitive.
>>
>> >
>> >thanks doug
>>
>> What would you do next if you found a cannon?
>>
>>
>> --
>>
>> John Larkin Highland Technology, Inc
>> picosecond timing precision measurement
>>
>> jlarkin att highlandtechnology dott com
>> http://www.highlandtechnology.com
>
>A bridge will be experimented with.
>Concerning using headphone. Can I just measure bridge balance
>with a frequency to voltage converter and measure voltage
>with my electrometer?
The frequency of the bridge null won't change; only its amplitude and
phase.
It sounds like you're not an electronics guy, so you could get some
help here. I suspect that lots of people would be interested.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics