Driver to drive?

[rickman]

On 11/20/2014 11:28 AM, Tim Williams wrote:

"legg" <legg@nospam.magma.ca> wrote in message
news:26qr6a9nfcf0dehq7rotu3tpc4an1jq24g@4ax.com...
Similar complexity is present in semiconductor large scale integration
or optical interfaces. It's there, but you just don't notice it except
perhaps as a more frequent junking of some device that used to last
for decades.

Some applications simply defy miniaturization. Some will never last
long enough to justify the effort. The first attempt is often the
end-run, trying to avoid the need for so many individual terminations.

Compactrons come to mind.

I've got to imagine tubes could be pretty slick these days with MEMS.

If they had MEMS back in the day, they could've done some really neat
stuff, integrated TV receiver - demodulator - chroma separator, say.

Of course... "neat stuff" would include transistors, so we'd still be
where we are today without the glowbugs. :^)

I seem to recall there was a UK company with a plan to produce a pre-LCD
display using very pointy field emitters. I can't recall if they were
etched in Si, or what. Is that the sort of thing you are referring to
with MEMS tubes?

I believe this company never shipped a commercial product.

--

Rick

 

> You could also get a 6V 3A wart cheap.

Life is never so simple... I bench checked the power supplies, and they're actually all 5.45V (same reading loaded and unloaded), not 6V as stated on the label. There's also a "5V 3A" labeled power supply from the same company that measures out at 5.45V.

These are for LED Christmas lights, and I'm unsure that boosting the voltage from 5.5V to 6V using a standard wall wart is a good idea. I suppose I could take a 6V wall wart and put a standard silicon diode in front of it, and that should yield pretty close to what this 5.45V supply is putting out.

 

[Lasse Langwadt Christense]

Den fredag den 21. november 2014 00.13.49 UTC+1 skrev Jamie M:

On 11/19/2014 6:58 PM, sroberts6328@gmail.com wrote:
Here is a detailed thesis on the matter

http://etheses.whiterose.ac.uk/378/1/uk_bl_ethos_400851.pdf

At lower laser powers a copper doped stainless steel powder is the material of choice. The copper aids in bonding the steel particles.

This still needs fusing in a furnace.

Steve


Hi,

Have you ever come across a wire feed laser welder? I was thinking
something like a MIG welder, but using a laser instead of the electrical
arc. If the wire feed was small enough diameter something like this
could be used for 3D printing too.

cheers,
Jamie

http://youtu.be/b5Xi1LfeJdw

-Lasse

 

[Mikko OH2HVJ]

Don Y <this@is.not.me.com> writes:

single sector performance are you
likely to encounter in that environment? E.g., a desktop disk can
easily saturate a 100Mb link -- or a USB2 PCI i/f. I'm not sure
that is true with many (?) laptop drives...

I've done a lot of database related performance measurements during the last months.
Typically a cheap 500GB 5400RPM 2.5" SATA disk can sustain about 30-40MB/s with large
(1MB) files, which are typically quite quite well located. With very small files
all bets are off, as the read head will need to do a lot of work. I've seen even
numbers less than 1MB/s in such cases.

When measuring disk performance, remember to read much more data (or at least new data)
than you've got RAM. Modern OSs cache aggressively. I've used bonnie++ for comparing
performance on different setups.

I don't have any numbers to give, but with 7200RPM similar disk my laptop felt much faster.

With SSDs you'll get much higher numbers, of course. Especially small file performance
improvement will be huge. My target has been 'rust drives', as 500TB of SSD still
costs a lot.

--
mikko OH2HVJ

 

[Don Y]

On 11/20/2014 12:03 PM, Mikko OH2HVJ wrote:

Don Y <this@is.not.me.com> writes:

But, what sort of unbuffered,[1] single sector performance are you likely
to encounter in that environment? E.g., a desktop disk can easily
saturate a 100Mb link -- or a USB2 PCI i/f. I'm not sure that is true
with many (?) laptop drives...

I've done a lot of database related performance measurements during the last
months. Typically a cheap 500GB 5400RPM 2.5" SATA disk can sustain about
30-40MB/s with large (1MB) files, which are typically quite quite well
located.

Yeah, big files alter the results dramatically. Especially if they can
exploit contiguous location on the medium.

With very small files all bets are off, as the read head will need to do a
lot of work. I've seen even numbers less than 1MB/s in such cases.

I've been seeing numbers in the 2MB/s range -- but, that's at the end of a
significant pipeline, as well (and, with just "sector accesses" -- though the
OS will obviously be buffering).

When measuring disk performance, remember to read much more data (or at
least new data) than you've got RAM. Modern OSs cache aggressively. I've
used bonnie++ for comparing performance on different setups.

I'm not trying to measure what the disk *can* do but, rather, understand the
low numbers I was seeing. E.g., even a USB2 drive would typically be moving
~15M/s (1GB/min). I was processing ~80G of data (but in sector sized pieces)
and seeing total execution times in *hours* instead of "an hour or so".

I don't have any numbers to give, but with 7200RPM similar disk my laptop
felt much faster.

No doubt. And, figure most (of my) workstations are 10K and 15K drives
so there's a significant difference in expectation. Likewise, the USB2
drives I was comparing against I had tended to use in big transfers
so there wasn't all these syscalls and traps to eat up cycles.

With SSDs you'll get much higher numbers, of course. Especially small file
performance improvement will be huge. My target has been 'rust drives', as
500TB of SSD still costs a lot.

Exactly. One of the questions I'm trying to answer is "where" it makes
the most sense to access a drive's content:
+ on the laptop (with a "power optimized" CPU of varying ability)
*or*
+ ship it off to a server that can copy it to a faster medium (RAM/SSD)

By way of analogy with your DBMS apps: if you had many small(er) DB's
and only needed to run one at a time, it might be faster to move the
entire DB onto an SSD, run it there, then ship the updated DB back to
its original medium (sort of as "tertiary storage").

That would allow a small(er) SSD to give you high performance at the
cost of these two "copy's" (because the DB's content is accessed many
times so the cost of the copy quickly falls into the noise when
compared to the relative speedup of the SSD accesses)

 

On Thursday, November 20, 2014 11:20:23 PM UTC, John Larkin wrote:

On Thu, 20 Nov 2014 14:24:36 -0800 (PST), smbaker@gmail.com wrote:

You could also get a 6V 3A wart cheap.

Life is never so simple... I bench checked the power supplies, and they're actually all 5.45V (same reading loaded and unloaded), not 6V as stated on the label. There's also a "5V 3A" labeled power supply from the same company that measures out at 5.45V.

These are for LED Christmas lights, and I'm unsure that boosting the voltage from 5.5V to 6V using a standard wall wart is a good idea. I suppose I could take a 6V wall wart and put a standard silicon diode in front of it, and that should yield pretty close to what this 5.45V supply is putting out.



If you run the LED string from one 1.5A 5.45 or 6 volt supply, it's
likely to look just fine. The supply may current limit and cost you a
little brightness. No harm done. Again, try it. Nothing bad is likely
to happen.

If it blinks, you have a shutdown/retry type supply, which wouldn't
look good on a christmas tree.

some people might like it


NT

 

If you run the LED string from one 1.5A 5.45 or 6 volt supply, it's
likely to look just fine. The supply may current limit and cost you a
little brightness. No harm done. Again, try it. Nothing bad is likely
to happen.

They GE G35 'Color Effects' bulbs and have a digital logic (microcontroller?) on each bulb. That's why I'm concerned about what might happen if there's too much supply. Could be they chose 5.5V specifically to maximize brightness without destroying the logic.

I suppose I should dissect one of the bulbs and see what kind of controller it is using and/or whether there is on-board regulation.

 

[legg]

On Thu, 20 Nov 2014 11:36:06 -0500, rickman <gnuarm@gmail.com> wrote:

On 11/20/2014 11:28 AM, Tim Williams wrote:
"legg" <legg@nospam.magma.ca> wrote in message
news:26qr6a9nfcf0dehq7rotu3tpc4an1jq24g@4ax.com...
Similar complexity is present in semiconductor large scale integration
or optical interfaces. It's there, but you just don't notice it except
perhaps as a more frequent junking of some device that used to last
for decades.

Some applications simply defy miniaturization. Some will never last
long enough to justify the effort. The first attempt is often the
end-run, trying to avoid the need for so many individual terminations.

Compactrons come to mind.

I've got to imagine tubes could be pretty slick these days with MEMS.

If they had MEMS back in the day, they could've done some really neat
stuff, integrated TV receiver - demodulator - chroma separator, say.

Of course... "neat stuff" would include transistors, so we'd still be
where we are today without the glowbugs. :^)

I seem to recall there was a UK company with a plan to produce a pre-LCD
display using very pointy field emitters. I can't recall if they were
etched in Si, or what. Is that the sort of thing you are referring to
with MEMS tubes?

I believe this company never shipped a commercial product.

You're possibly thinking of field emission triodes and arrays. I
believe the issue was with erosion of the emitter (even with vapor
deposited diamond surfaces). They were etched in Si, GaAs and InP.
Not much published after Y2K.

Field emission was also a consideration for Ion Propulsion thrusters.

RL

 

[Tim Williams]

"rickman" <gnuarm@gmail.com> wrote in message
news:m4l5ae$qhf$3@dont-email.me...

I seem to recall there was a UK company with a plan to produce a pre-LCD
display using very pointy field emitters. I can't recall if they were
etched in Si, or what.

Sounds like modern-day* plasma panels.

*Are they still made? I suppose large LCD panels have pretty much
trounced them, but I don't follow that market.

But that's a glow discharge. A VFD is thermionic, but not printed (well,
the electrodes might be etched, but there's plenty of stampings involved,
too).

There was also a "flat panel CRT", this thing for example:
https://www.youtube.com/watch?v=qCJPF6Ei3Vw
I'd never seen one before the video, pretty cool.

> Is that the sort of thing you are referring to with MEMS tubes?

Nah, I mean building proper thermionic tubes the way we make ICs (and
MEMS) today. For example, maybe you'd have a thin Al2O3 substrate
(doesn't need to be single crystal), with a tungsten foil backing that's
etched for filaments and connecting tracks, and whatever on the front
(nichrome foil?). The front foil is etched to produce a grid (holes,
slots, whatever; a remote cutoff characteristic could be made with tapered
slots), and the Al2O3 is etched through where electron flow is desired.
The hard part is building a second layer on top of this, for plates (or
screens for tetrodes+) and other connections. Perhaps a suitable
thickness of Al2O3 could be sputtered/evaporated on top and etched back,
much as metal layers are implemented in semiconductors today.

Assuming the physics works out, it should at least be scalable -- you can
make a triode in a fraction of a grain of sand, or you can array a
thousand of them in parallel for heavy lifting.

Basic analysis includes: achieving suitable aspect ratios for grids,
electrode spacings for voltage standoff, low enough thermal conductivity
to get the cathode working, sufficient stiffness so all the foils don't
simply fall apart, and so on.

And you could include, say, planar inductors, to build one hell of a
distributed amplifier. (Maybe one of the ceramic layers is ferrite loaded
epoxy paste?)

Would it be at all competitive with MOSFETs? Doubtful. Even with the
large advantage in electron velocity*, the effective* mobility of any
semiconductor is orders of magnitude higher than vacuum, for the simple
fact that, rather than being space, it's space loaded with ions, balancing
the charge and allowing way higher carrier density. And more current
basically means more gain, end of story.

*Equivalent and wave-of-the-hands approximated, since vacuum physics is
ballistic physics, not thermalized. Some semiconductors get close (e.g.,
the underlying 'snappy' phenomenon in GaAs Gunn diodes), and the better
structures (2DEG) and materials (GaN?) are probably even better than that.

Tim

--
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com

 

On Friday, November 21, 2014 1:13:17 AM UTC, smb...@gmail.com wrote:

If you run the LED string from one 1.5A 5.45 or 6 volt supply, it's
likely to look just fine. The supply may current limit and cost you a
little brightness. No harm done. Again, try it. Nothing bad is likely
to happen.

They GE G35 'Color Effects' bulbs and have a digital logic (microcontroller?) on each bulb. That's why I'm concerned about what might happen if there's too much supply. Could be they chose 5.5V specifically to maximize brightness without destroying the logic.

Yep. I forget what psus you have, but diodes or schottky diodes can always drop some. No, they dont drop 0.6v at rated i.


> I suppose I should dissect one of the bulbs and see what kind of controller it is using and/or whether there is on-board regulation.

NT

 

On Thursday, November 20, 2014 3:01:39 PM UTC, Martin Brown wrote:

On 20/11/2014 05:40, jurb6006@gmail.com wrote:
On a forum, I read this :

"I am the proud new owner of a 2270. It seems to be in pretty good shape, but I noticed today that it seems like all the radio stations at once are coming from the left channel. The volume knob doesn't affect it, as it is the same level no matter where you turn it to. Changing the input selector doesn't help, and neither does moving the tuner. What is going on? "

Sounds more like local taxis breakthrough on the power amplifier to
speaker lead. A signal that doesn't depend on the input selector or
volume control isn't going through either!

The thread contiues with some details, these are FM stations. I can understand if it is AM, but FM ? He says it is about ten stations all at once, though that is probably subjective, it could be "only" five.

I can't see any way that normal FM channels could appear only on the
left channel of a stereo pair. In all the places I know they transmit
stereo as L+R and L-R except in Japan during bilingual news
transmission. (When L+R = Japanese and L-R = English)

What, in a regular audio reciever could demodulate multiple FM staions up in around 100 mHz that have a measely 75 kHz deviation ?

Could this have something to do with this digital stuff in the signal now ?

I shudder to think how this could happen as described unless there is
something else present causing massive intermodulation distortion.

Maybe the positive feedback valve is misbiased, causing frequency drift of the tuning tank


NT

 

[Jamie M]

On 11/19/2014 6:15 PM, sroberts6328@gmail.com wrote:
> Also check to see if the Co2 will run vertically before you buy it. Some cheap tubes do have a thermal gradient issue. Has to

do with convective gas flow patterns in the tube.

I'll be shocked if you get good structural strength at 40 watts.


Phil's numbers strike me as highly optimistic. I can barely cut thin steel shim stock at 40 watts on a professional laser cutter,

with assist gas. I would not even try to weld it.

Steve

Hi,

Thanks for the info about the thermal gradient issue, I guess this could
cause overheating near the top of the tube..

Also what is your cutting beam diameter approx at 40watts? Do you ever
have problems with metal splatter onto the optical components?

Phil's example used a 50micron focus beam diameter, about 0.002",
is your shim stock about that thickness too? What do you think you
could cut without the assist gas? I think that thickness might be the
high end of what powder thickness could be welded.

I came up with a simple idea for a metal powder leveler that is just a
fixed horizontal bar attached to the spindle/toolholder axis, and at a
fixed height so that it always levels the metal powder to the exact
height of laser beam focus, this way when the Z stage goes up to melt
the next layer of metal, the levelling bar also goes up the same amount
and levels the powder, which there is an excess pile of.

cheers,
Jamie


>

 

[Jamie M]

On 11/19/2014 6:58 PM, sroberts6328@gmail.com wrote:

Here is a detailed thesis on the matter

http://etheses.whiterose.ac.uk/378/1/uk_bl_ethos_400851.pdf

At lower laser powers a copper doped stainless steel powder is the material of choice. The copper aids in bonding the steel particles.

This still needs fusing in a furnace.

Steve

Thanks!

 

[Jamie M]

On 11/19/2014 6:58 PM, sroberts6328@gmail.com wrote:

Here is a detailed thesis on the matter

http://etheses.whiterose.ac.uk/378/1/uk_bl_ethos_400851.pdf

At lower laser powers a copper doped stainless steel powder is the material of choice. The copper aids in bonding the steel particles.

This still needs fusing in a furnace.

Steve

Hi,

Have you ever come across a wire feed laser welder? I was thinking
something like a MIG welder, but using a laser instead of the electrical
arc. If the wire feed was small enough diameter something like this
could be used for 3D printing too.

cheers,
Jamie

 

On Thursday, November 20, 2014 7:06:22 PM UTC-5, Maynard A. Philbrook Jr. wrote:

In article <227fa5bf-db57-412f-8fb7-a27513ada1c1@googlegroups.com>,
dakupoto@gmail.com says...

Could some electronics guru pleas explain what
a "self-ballasted" LED lamp mean ? I have seen
LED lamps, running off the AC line, and powered
by a simple small 5V 1 Amp SMPS, but what exactly
does a self-ballasted LED lamp mean ?

it means it has the require components inside to
accommodate a direct connection to a commonly known
source.

Even with that, you still need to ensure you get the
correct one that matches the voltage you are attaching
it to.

Jamie

Thanks. Your explanation seems to be the most likely one.
We were looking at specifications for certification of
AC wall socket compatible LED lamp in as Asian country.

 

[John Larkin]

On Thu, 20 Nov 2014 14:24:36 -0800 (PST), smbaker@gmail.com wrote:

You could also get a 6V 3A wart cheap.

Life is never so simple... I bench checked the power supplies, and they're actually all 5.45V (same reading loaded and unloaded), not 6V as stated on the label. There's also a "5V 3A" labeled power supply from the same company that measures out at 5.45V.

These are for LED Christmas lights, and I'm unsure that boosting the voltage from 5.5V to 6V using a standard wall wart is a good idea. I suppose I could take a 6V wall wart and put a standard silicon diode in front of it, and that should yield pretty close to what this 5.45V supply is putting out.

If you run the LED string from one 1.5A 5.45 or 6 volt supply, it's
likely to look just fine. The supply may current limit and cost you a
little brightness. No harm done. Again, try it. Nothing bad is likely
to happen.

If it blinks, you have a shutdown/retry type supply, which wouldn't
look good on a christmas tree.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Clifford Heath]

On 19/11/14 09:02, rickman wrote:

Thanks for helping me understand this.

Now I need to figure out why the Cascode design doesn't deliver a higher
gain. It should, right? Ah, I just found it. He left the output on
the drain to emitter leg and the output is now on the collector! That's
much better giving some 75 dB at 60 kHz now.

Thanks, I think I learned a few things. Now if I can bias the circuit
properly.

I've previously mentioned my 350MHz RF probe/amplifier, which uses a
cascode. If you want to explore it in LTSpice, the full design files and
performance measurements are here:

<http://cjh.polyplex.org/electronics/RFCascodeProbe/>

The bandwidth is limited by the Ciss of the FET and the probe lead
inductance.

Something I don't understand, which someone more experienced might be
able to explain, is why I had to add such a large source resistance to
the input to kill the resonance between the input inductance and the
Ciss. Input inductance is approximately right for a pair of 4mm probes,
and they won't have appreciable resistance. What kills this resonance in
real life?

Clifford Heath.

 

[Maynard A. Philbrook Jr.]

In article <227fa5bf-db57-412f-8fb7-a27513ada1c1@googlegroups.com>,
dakupoto@gmail.com says...

Could some electronics guru pleas explain what
a "self-ballasted" LED lamp mean ? I have seen
LED lamps, running off the AC line, and powered
by a simple small 5V 1 Amp SMPS, but what exactly
does a self-ballasted LED lamp mean ?

it means it has the require components inside to
accommodate a direct connection to a commonly known
source.

Even with that, you still need to ensure you get the
correct one that matches the voltage you are attaching
it to.

Jamie

 

[rickman]

On 11/20/2014 4:29 PM, legg wrote:

On Thu, 20 Nov 2014 11:36:06 -0500, rickman <gnuarm@gmail.com> wrote:

On 11/20/2014 11:28 AM, Tim Williams wrote:
"legg" <legg@nospam.magma.ca> wrote in message
news:26qr6a9nfcf0dehq7rotu3tpc4an1jq24g@4ax.com...
Similar complexity is present in semiconductor large scale integration
or optical interfaces. It's there, but you just don't notice it except
perhaps as a more frequent junking of some device that used to last
for decades.

Some applications simply defy miniaturization. Some will never last
long enough to justify the effort. The first attempt is often the
end-run, trying to avoid the need for so many individual terminations.

Compactrons come to mind.

I've got to imagine tubes could be pretty slick these days with MEMS.

If they had MEMS back in the day, they could've done some really neat
stuff, integrated TV receiver - demodulator - chroma separator, say.

Of course... "neat stuff" would include transistors, so we'd still be
where we are today without the glowbugs. :^)

I seem to recall there was a UK company with a plan to produce a pre-LCD
display using very pointy field emitters. I can't recall if they were
etched in Si, or what. Is that the sort of thing you are referring to
with MEMS tubes?

I believe this company never shipped a commercial product.

You're possibly thinking of field emission triodes and arrays. I
believe the issue was with erosion of the emitter (even with vapor
deposited diamond surfaces). They were etched in Si, GaAs and InP.
Not much published after Y2K.

Field emission was also a consideration for Ion Propulsion thrusters.

Wikipedia to the rescue.

http://en.wikipedia.org/wiki/Field_emission_display

They describe it as being printed but to mention the need for a higher
vacuum than is used in a CRT. As to who was doing the development, I
may well be confusing Sir Clive Sinclare's flat CRT with this display.
The wiki article does not say anyone ever produced a commercial product
using this technology.

--

Rick

 

[mike]

On 11/20/2014 3:20 PM, John Larkin wrote:

On Thu, 20 Nov 2014 14:24:36 -0800 (PST), smbaker@gmail.com wrote:

You could also get a 6V 3A wart cheap.

Life is never so simple... I bench checked the power supplies, and they're actually all 5.45V (same reading loaded and unloaded), not 6V as stated on the label. There's also a "5V 3A" labeled power supply from the same company that measures out at 5.45V.

These are for LED Christmas lights, and I'm unsure that boosting the voltage from 5.5V to 6V using a standard wall wart is a good idea. I suppose I could take a 6V wall wart and put a standard silicon diode in front of it, and that should yield pretty close to what this 5.45V supply is putting out.



If you run the LED string from one 1.5A 5.45 or 6 volt supply, it's
likely to look just fine. The supply may current limit and cost you a
little brightness. No harm done. Again, try it. Nothing bad is likely
to happen.

If it blinks, you have a shutdown/retry type supply, which wouldn't
look good on a christmas tree.

I don't suppose you've considered the obvious...
running half the lights from each supply???