joule capacity of surface-mount resistors

[John Larkin]

Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
like to discharge about 35 joules of energy from some electrolytic
caps, in a couple tenths of a second maybe, and it would be cool to
use a few 2512 or some such resistors.

I suppose I could try it...



--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

[Joerg]

John Larkin wrote:
>
> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> like to discharge about 35 joules of energy from some electrolytic
> caps, in a couple tenths of a second maybe, and it would be cool to
> use a few 2512 or some such resistors.
>
> I suppose I could try it...
>

Not into SMT but thru-hole. Ohmite has Joule ratings for some but I'd
contact them because 200msec is long:

http://www.e-sonic.com/aboutus/cat/R/resistors.pdf
http://www.ohmite.com/

Example: Page 141 bottom left

Usually high pulse load calls for carbon resistor types.

--
Regards, Joerg

http://www.analogconsultants.com/

[tm]

"Joerg" <inv...@invalid.invalid> wrote in message
news:b0545c...@mid.individual.net...

Put it in LN2 i.e. IRC.

[John Larkin]

On Wed, 22 May 2013 16:54:10 -0700, Joerg <inv...@invalid.invalid>
wrote:

Test: 2512, thickfilm, 0.2 ohms 1%, soldered to lots of copper.

Dumped 10,000 uF at 10 volts, 0.5 joules.

Blew it open first try. Guess I'll try some wirewounds.

[Vladimir Vassilevsky]

On 5/22/2013 6:42 PM, John Larkin wrote:
>
> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> like to discharge about 35 joules of energy from some electrolytic
> caps, in a couple tenths of a second maybe, and it would be cool to
> use a few 2512 or some such resistors.
>
> I suppose I could try it...

I did that. No good idea. The 2512 develops hot spots which burn out.

Vladimir Vassilevsky
DSP and Mixed Signal Designs
www.abvolt.com

[Vladimir Vassilevsky]

Joules assume more or less equilibrium state.
For surge, I^2 x T rating is more appropriate.

[tm]

"John Larkin" <jla...@highlandtechnology.com> wrote in message
news:6snqp8h4b8fsq367l...@4ax.com...

> On Wed, 22 May 2013 16:54:10 -0700, Joerg <inv...@invalid.invalid>
> wrote:
>
>>John Larkin wrote:
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>>
>>> I suppose I could try it...
>>>
>>
>>Not into SMT but thru-hole. Ohmite has Joule ratings for some but I'd
>>contact them because 200msec is long:
>>
>>http://www.e-sonic.com/aboutus/cat/R/resistors.pdf
>>http://www.ohmite.com/
>>
>>Example: Page 141 bottom left
>>
>>Usually high pulse load calls for carbon resistor types.
>
> Test: 2512, thickfilm, 0.2 ohms 1%, soldered to lots of copper.
>
> Dumped 10,000 uF at 10 volts, 0.5 joules.
>
> Blew it open first try. Guess I'll try some wirewounds.
>
>
> --
>
> John Larkin Highland Technology, Inc

Why don't you start out on the low end and see where it fails?

tm

[Jeff Liebermann]

On Wed, 22 May 2013 16:42:32 -0700, John Larkin
<jla...@highlandtechnology.com> wrote:

>Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>like to discharge about 35 joules of energy from some electrolytic
>caps, in a couple tenths of a second maybe, and it would be cool to
>use a few 2512 or some such resistors.
>
>I suppose I could try it...

Welcome to Learn by Destroying(tm). You get to have all the fun
blowing up resistors. I'm jealous.

A really rough estimate of what could be expected in the size of the
resitors could be calculated from the specific heat of ceramic. This
doesn't include hot spots, uneven radiation, conduction to the PCB,
differences in material, current density (fusing), and whatever else I
forgot, but should be in the ballpark as far as the phyical weight of
the device that you're trying to vaporize. I'll guess(tm) that a
resistor can tolerate a 70C temp rise and that the specific heat of
ceramic is 1050 J/kg-C.
kg = 1 / (70 * 1050) = 0.0136 grams
A 2513 resistor is about 0.0513 grams so it should be possible.
Therefore the problem is probably hot spots or current density causing
the resistor material to act like a fuse. If you can find a chip
resistor that uses bulk resistivity instead of a surface painted
trace, I think it might work. Something like this (which I've never
used or tried):
<http://www.vishay.com/docs/30100/wsl.pdf>
I've used such chip resitors in RF dummy loads with good success.




--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[DecadentLinuxUserNumeroUno]

On Wed, 22 May 2013 16:42:32 -0700, John Larkin
<jla...@highlandtechnology.com> wrote:

>
>

>Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>like to discharge about 35 joules of energy from some electrolytic
>caps, in a couple tenths of a second maybe, and it would be cool to
>use a few 2512 or some such resistors.
>
>I suppose I could try it...

Get a wirewound and make it into a MELF or get a bulk carbon comp and
snip and form the leads to make a standing, leaded MELF thingy.

35 joules into a surface mount resistor even slowly would likely open
it up.

[George Herold]

On May 22, 7:42 pm, John Larkin <jlar...@highlandtechnology.com>
wrote:

> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> like to discharge about 35 joules of energy from some electrolytic
> caps, in a couple tenths of a second maybe, and it would be cool to
> use a few 2512 or some such resistors.
>
> I suppose I could try it...
>
> --
>
> John Larkin         Highland Technology, Inc
>

> jlarkin at highlandtechnology dot comhttp://www.highlandtechnology.com

>
> Precision electronic instrumentation
> Picosecond-resolution Digital Delay and Pulse generators
> Custom laser drivers and controllers
> Photonics and fiberoptic TTL data links
> VME thermocouple, LVDT, synchro   acquisition and simulation

I think we use a big zener diode to soak up energy from a coil.

George H.

[Jeff Liebermann]

On Wed, 22 May 2013 19:37:09 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>Something like this (which I've never
>used or tried):
><http://www.vishay.com/docs/30100/wsl.pdf>

Oops. Bad example as it's too low resistance.
Nothing in bulk resistivity here:
<http://www.vishay.com/resistors-linear/1206-to-2512/>
<http://www.vishay.com/resistors-linear/larger-than-2512/>
Foil is too low resistance, thick film can't handle the current
density, so I guess it has to be wirewound.

[John Larkin]

Tomorrow maybe. Had to leave at 5:30.

Higher resistor values might do better, but it looks like there's no way I'm
going to dump 35 or so joules into any reasonable array of regular surface-mount
resistors.

I may have to stand up a leaded wirewound part, roughly 0.25" dia x 1" long.
Inelegant.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

[John Larkin]

On Wed, 22 May 2013 19:37:09 -0700, Jeff Liebermann <je...@cruzio.com> wrote:

>On Wed, 22 May 2013 16:42:32 -0700, John Larkin
><jla...@highlandtechnology.com> wrote:
>
>>Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>like to discharge about 35 joules of energy from some electrolytic
>>caps, in a couple tenths of a second maybe, and it would be cool to
>>use a few 2512 or some such resistors.
>>
>>I suppose I could try it...
>
>Welcome to Learn by Destroying(tm). You get to have all the fun
>blowing up resistors. I'm jealous.

You can blow up resistors too!

We're also designing a power mosfet exploding circuit.

>
>A really rough estimate of what could be expected in the size of the
>resitors could be calculated from the specific heat of ceramic. This
>doesn't include hot spots, uneven radiation, conduction to the PCB,
>differences in material, current density (fusing), and whatever else I
>forgot, but should be in the ballpark as far as the phyical weight of
>the device that you're trying to vaporize. I'll guess(tm) that a
>resistor can tolerate a 70C temp rise and that the specific heat of
>ceramic is 1050 J/kg-C.
> kg = 1 / (70 * 1050) = 0.0136 grams
>A 2513 resistor is about 0.0513 grams so it should be possible.
>Therefore the problem is probably hot spots or current density causing
>the resistor material to act like a fuse. If you can find a chip
>resistor that uses bulk resistivity instead of a surface painted
>trace, I think it might work. Something like this (which I've never
>used or tried):
><http://www.vishay.com/docs/30100/wsl.pdf>
>I've used such chip resitors in RF dummy loads with good success.

--

John Larkin Highland Technology Inc

www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

[tm]

"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
news:or4rp8dh010dv4fuf...@4ax.com...

How about a manganin ribbon? How much space do you have? 35 J is a lot of
energy to dump. Maybe a lamp (or several) of some sort might be able to do
it.

[mi]

Jeff Liebermann <je...@cruzio.com> writes:

> kg = 1 / (70 * 1050) = 0.0136 grams

Make that 0.0136 kg = 13.6 grams. 250 resistors should be enough.

If the dumping is done relatively infrequently, the heat capacity and
pulse power capacity are the limiting factors, the smallest solution is
probably a few carbon/ceramic composition resistors like Ohmite OX/OY series.

--
Mikko OH2HVJ

[John Fields]

---
http://www.globar.com/ec/bulk-ceramic-resistors

--
JF

[Wimpie]

El 23-05-13 1:42, John Larkin escribi�:

>
>
> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> like to discharge about 35 joules of energy from some electrolytic
> caps, in a couple tenths of a second maybe, and it would be cool to
> use a few 2512 or some such resistors.
>
> I suppose I could try it...
>
>
>

Hello,

Try to locate the chip resistor datasheet (introduction thick film) on
http://www.yageo.com/portal/product/open_literature.jsp?SWITCH_CATEGORY=/product/open_literature

This shows data for pulse handling for SMD resistors. It may be helpful.

--
Wim
PA3DJS
www.tetech.nl
Please remove abc first in case of PM

[Klaus Kragelund]

On Thursday, May 23, 2013 1:42:32 AM UTC+2, John Larkin wrote:
> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>
> like to discharge about 35 joules of energy from some electrolytic
>
> caps, in a couple tenths of a second maybe, and it would be cool to
>
> use a few 2512 or some such resistors.
>
>
>
> I suppose I could try it...

You could use the better thermal coupling of an active part, like the SI8445 FET:

http://www.vishay.com/docs/69984/si8445db.pdf

A quick glance reveals thermal impedance, single shot, of 15K/W for 1s pulse. So you should be able to drive about at least 6 Joule into that device.

If you can couple very good thermally to the foot, you can get up to at least 20Joule

Most likely there is other parts with better specs than that.

Regards

Klaus

[Klaus Kragelund]

This one is even better:

http://www.nxp.com/documents/data_sheet/PSMN1R2-25YL.pdf

0.4K/W in a SO8 size package, but you need to stich vias into several layers to get the heat away from the package/PCB area.

Cheers

Klaus

[Jeff Liebermann]

On Thu, 23 May 2013 08:39:47 +0300, mi
<mi...@labserve1.i-did-not-set--mail-host-address--so-tickle-me>
wrote:

>Jeff Liebermann <je...@cruzio.com> writes:
>
>> kg = 1 / (70 * 1050) = 0.0136 grams
>
>Make that 0.0136 kg = 13.6 grams. 250 resistors should be enough.

Thanks. I erred, but not where you pointed out.

kg = 1 / (70 * 1050) = 1.36*10^-5 kg
Converting to grams
g = 1.36*10-5 * 1*10^3 g/kg = 1.36*10^-2 g = 0.0136 g
For 35 joules
g = 35 * 0.0136 = 0.48 g
For a 0.05 gram 2513 resistor
0.48 / 0.05 = 10 resistors required.

>If the dumping is done relatively infrequently, the heat capacity and
>pulse power capacity are the limiting factors, the smallest solution is
>probably a few carbon/ceramic composition resistors like Ohmite OX/OY series.

As I mumbled, this was an approximation.

[Joerg]

More elegant:

http://www.vishay.com/docs/30102/wscwsn.pdf

They even come Ayrton-Perry style if you need low inductance. You'll
have to inquire about pulse dump capabilities because the datasheet is
less than forthcoming in that domain.

[John Larkin]

On Thu, 23 May 2013 03:51:11 -0500, John Fields <jfi...@austininstruments.com>

Yeah, I guess the summary is that the heat has to be generated all through the
bulk of the resistive material. Most insulators conduct heat slowly enough that
the element gets all the energy initially, so it vaporizes. Even most wirewound
resistors make the heat in a small fraction of the total volume.

I might be able to use their 234SP, standing up. It's rated 30 joules for 10
milisecond pulses, apparently more for longer pulses.

http://www.globar.com/ec/bulk-ceramic-resistors/axial-leaded-resistors.html

If I discharge 30,000 uF through, say, 5 ohms, that's a 150 millisecond tau. A
carbon comp with that diameter+length might work too, if one existed.

Here's the board... this is a dummy layout, just pushing parts around and seeing
what might fit.

https://dl.dropboxusercontent.com/u/53724080/PCBs/D100_pads.jpg

That resistor might fit into the upper-left corner.

I think the Globar parts are carborundum, silicon carbide, which is hard to
vaporize.

Thanks

[Tim Wescott]

I've had to do that. Some resistors are rated for pulse service; a few
even have enough information for derating depending on the pulse length.

Were I doing this I'd start by digging around for data sheets that
actually specify pulse power dissipation. Unless I had _lots_ of time to
waste doing my own qualification I'd award the design win to the company
that actually specifies their products thoroughly.

And yes, 200ms is quite long.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Phil Hobbs]

The worry with those is probably thermal fatigue. I like the lamp idea.
A Maglite bulb might be about right.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[lang...@fonz.dk]

On May 23, 1:42 am, John Larkin <jlar...@highlandtechnology.com>
wrote:

> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> like to discharge about 35 joules of energy from some electrolytic
> caps, in a couple tenths of a second maybe, and it would be cool to
> use a few 2512 or some such resistors.
>
> I suppose I could try it...
>

these say 100J : http://www.ohmite.com/cat/res_tp.pdf


-Lasse

[John Larkin]

We have had big wirewounds fail from pulsed-load cycling in NMR
gradient drivers, without exceeding their peak rated power.

> A Maglite bulb might be about right.

The caps can be charged to 50 volts, and I'd like the equivalent of a
few ohms.

--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com

http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom laser drivers and controllers

Photonics and fiberoptic TTL data links

[John Larkin]

On Wed, 22 May 2013 16:54:10 -0700, Joerg <inv...@invalid.invalid>
wrote:

Just tried a 1/4 watt carbon comp, 4.7 ohms, discharging 10,000 uF. It
fell apart at 40 volts, 8 joules. That's impressive.

A 22 ohm 2-watt comp was fine at 60 volts, 18 j. Need to try some
bigger caps.

[John Larkin]

On Wed, 22 May 2013 19:50:52 -0700, DecadentLinuxUserNumeroUno
<DL...@DecadentLinuxUser.org> wrote:

>On Wed, 22 May 2013 16:42:32 -0700, John Larkin
><jla...@highlandtechnology.com> wrote:
>
>>
>>
>>Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>like to discharge about 35 joules of energy from some electrolytic
>>caps, in a couple tenths of a second maybe, and it would be cool to
>>use a few 2512 or some such resistors.
>>
>>I suppose I could try it...
>
> Get a wirewound and make it into a MELF or get a bulk carbon comp and
>snip and form the leads to make a standing, leaded MELF thingy.

Looks like I need volume to absorb the energy, and on this board, that
means I have to use all the height available. So I have to stand
something up on end. Ugly but necessaty.

>
> 35 joules into a surface mount resistor even slowly would likely open
>it up.

100 milliwatts for 350 seconds is 35 joules. An 0603 can do that.

[John Larkin]

On Thu, 23 May 2013 12:44:07 +0200, Wimpie <wima...@tetech.nl>
wrote:

>El 23-05-13 1:42, John Larkin escribió:

>>
>>
>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>> like to discharge about 35 joules of energy from some electrolytic
>> caps, in a couple tenths of a second maybe, and it would be cool to
>> use a few 2512 or some such resistors.
>>
>> I suppose I could try it...
>>
>>
>>
>Hello,
>
>Try to locate the chip resistor datasheet (introduction thick film) on
>http://www.yageo.com/portal/product/open_literature.jsp?SWITCH_CATEGORY=/product/open_literature
>
>This shows data for pulse handling for SMD resistors. It may be helpful.

Their axial 4-watt wirewound KNP400 is rated for 40 watts for 5
seconds, which is 200 joules. The chip parts don't look promising.

[Dimitrij Klingbeil]

"John Larkin" <jla...@highlandtechnology.com> wrote in message

news:umlqp8tbebit3o1de...@4ax.com...

>
>
> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> like to discharge about 35 joules of energy from some electrolytic
> caps, in a couple tenths of a second maybe, and it would be cool to
> use a few 2512 or some such resistors.

SMT resistors generally have poor pulse handling, AFAIK.

You could try an SMT inductor however: find one with enough copper volume
and appropriate DC resistance, connect a diode in anti-parallel to quench
the ringing and there you have what amounts essentially to a big wirewound
resistor :)

Unlikely to be precise, but if your goal is just to discharge some energy
storage caps on switch-off in order to keep them from storing charge
indefinitely and you don't care too much about the exact discharge waveform,
why not.

Greetings
Dimitrij

[George Herold]

On May 23, 1:26 pm, John Larkin <jlar...@highlandtechnology.com>
wrote:
> On Wed, 22 May 2013 16:54:10 -0700, Joerg <inva...@invalid.invalid>

> wrote:
>
>
>
>
>
> >John Larkin wrote:
>
> >> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
> >> like to discharge about 35 joules of energy from some electrolytic
> >> caps, in a couple tenths of a second maybe, and it would be cool to
> >> use a few 2512 or some such resistors.
>
> >> I suppose I could try it...
>
> >Not into SMT but thru-hole. Ohmite has Joule ratings for some but I'd
> >contact them because 200msec is long:
>
> >http://www.e-sonic.com/aboutus/cat/R/resistors.pdf
> >http://www.ohmite.com/
>
> >Example: Page 141 bottom left
>
> >Usually high pulse load calls for carbon resistor types.
>
> Just tried a 1/4 watt carbon comp, 4.7 ohms, discharging 10,000 uF. It
> fell apart at 40 volts, 8 joules. That's impressive.
>
> A 22 ohm 2-watt comp was fine at 60 volts, 18 j. Need to try some
> bigger caps.
>
> --
>
> John Larkin         Highland Technology, Inc
>

> jlarkin at highlandtechnology dot comhttp://www.highlandtechnology.com

>
> Precision electronic instrumentation
> Picosecond-resolution Digital Delay and Pulse generators
> Custom laser drivers and controllers
> Photonics and fiberoptic TTL data links

> VME thermocouple, LVDT, synchro   acquisition and simulation- Hide quoted text -
>
> - Show quoted text -

OK it seems like you just need a certain volume of 'resistor' to soak
up all the energy. So for a crazy idea, how about you dedicate a
layer of the pcb to make a resistor out of copper.
~0.4 J/g-K a 100 degree rise sounds a bit extreme (for one gram of
copper).

George H.

[Phil Hobbs]

On 05/23/2013 01:30 PM, John Larkin wrote:
> On Wed, 22 May 2013 19:50:52 -0700, DecadentLinuxUserNumeroUno
> <DL...@DecadentLinuxUser.org> wrote:
>
>> On Wed, 22 May 2013 16:42:32 -0700, John Larkin
>> <jla...@highlandtechnology.com> wrote:
>>
>>>
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>>
>>> I suppose I could try it...
>>
>> Get a wirewound and make it into a MELF or get a bulk carbon comp and
>> snip and form the leads to make a standing, leaded MELF thingy.
>
> Looks like I need volume to absorb the energy, and on this board, that
> means I have to use all the height available. So I have to stand
> something up on end. Ugly but necessaty.
>
>>
>> 35 joules into a surface mount resistor even slowly would likely open
>> it up.
>
> 100 milliwatts for 350 seconds is 35 joules. An 0603 can do that.
>
>
>

The other approach would be to mount a through-hole resistor on skinny
spacers, e.g. thin wall copper or teflon tubing, and put components
underneath.

[Klaus Kragelund]

Or dump the energy into a high voltage capacitor, discharging this secondary capacitor slowly

Cheers

Klaus

[John Larkin]

OK, say 3 ohms at 500 uohm/square. I'd need 6000 squares, maybe 60
inches of 10 mil trace. Not unreasonable. The paved area would be
fairly large, so it would be heating a lot of epoxy as well as copper.

[John Larkin]

On Thu, 23 May 2013 20:13:11 +0200, "Dimitrij Klingbeil"
<nos...@no-address.com> wrote:

>"John Larkin" <jla...@highlandtechnology.com> wrote in message
>news:umlqp8tbebit3o1de...@4ax.com...
>>
>>
>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>> like to discharge about 35 joules of energy from some electrolytic
>> caps, in a couple tenths of a second maybe, and it would be cool to
>> use a few 2512 or some such resistors.
>
>SMT resistors generally have poor pulse handling, AFAIK.
>
>You could try an SMT inductor however: find one with enough copper volume
>and appropriate DC resistance, connect a diode in anti-parallel to quench
>the ringing and there you have what amounts essentially to a big wirewound
>resistor :)

That is interesting. One could estimate the mass of the copper (or
unwind it and weigh it) to compute peak temperature. The
metal-to-insulator mass ratio of an inductor may well be better than a
typical wirewound resistor.

With 30,000 uF of electrolytics, I'd expect the Q to be so low that
the diode wouldn't be necessary.

Cool. Gotta think about that one.

[tm]

"John Larkin" <jla...@highlandtechnology.com> wrote in message

news:4vrsp8936sudso5ep...@4ax.com...

> On Thu, 23 May 2013 20:13:11 +0200, "Dimitrij Klingbeil"
> <nos...@no-address.com> wrote:
>
>>"John Larkin" <jla...@highlandtechnology.com> wrote in message
>>news:umlqp8tbebit3o1de...@4ax.com...
>>>
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>
>>SMT resistors generally have poor pulse handling, AFAIK.
>>
>>You could try an SMT inductor however: find one with enough copper volume
>>and appropriate DC resistance, connect a diode in anti-parallel to quench
>>the ringing and there you have what amounts essentially to a big wirewound
>>resistor :)
>
> That is interesting. One could estimate the mass of the copper (or
> unwind it and weigh it) to compute peak temperature. The
> metal-to-insulator mass ratio of an inductor may well be better than a
> typical wirewound resistor.
>
> With 30,000 uF of electrolytics, I'd expect the Q to be so low that
> the diode wouldn't be necessary.
>
> Cool. Gotta think about that one.
>
>
> --
>
> John Larkin Highland Technology, Inc
>

What are you using to switch the load?

[John Larkin]

On Thu, 23 May 2013 16:17:59 -0400, "tm" <No_on...@white-house.gov>

The load is a bar laser, up to maybe 25 volts and 250 amps pulsed
power, controlled by a mess of mosfets. The resistor is between the
capacitor bank and a customer's DC power supply. It serves several
functions, like limiting poweron current surge, accidental shorts to
ground, and keeps his (switching?) supply from going nuts after every
laser pulse.

--

John Larkin Highland Technology, Inc

[Wimpie]

El 23-05-13 19:43, John Larkin escribi�:

> On Thu, 23 May 2013 12:44:07 +0200, Wimpie<wima...@tetech.nl>
> wrote:
>

>> El 23-05-13 1:42, John Larkin escribi�:

>>>
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>>
>>> I suppose I could try it...
>>>
>>>
>>>
>> Hello,
>>
>> Try to locate the chip resistor datasheet (introduction thick film) on
>> http://www.yageo.com/portal/product/open_literature.jsp?SWITCH_CATEGORY=/product/open_literature
>>
>> This shows data for pulse handling for SMD resistors. It may be helpful.
>
> Their axial 4-watt wirewound KNP400 is rated for 40 watts for 5
> seconds, which is 200 joules. The chip parts don't look promising.
>
>

Hello John,

I know you need lots of small chip parts to handle your pulse, so if
you can live with the inductance of a wire wound resistor it may be a
better choice.

[amdx]

On 5/23/2013 12:30 PM, John Larkin wrote:
> On Wed, 22 May 2013 19:50:52 -0700, DecadentLinuxUserNumeroUno
> <DL...@DecadentLinuxUser.org> wrote:
>
>> On Wed, 22 May 2013 16:42:32 -0700, John Larkin
>> <jla...@highlandtechnology.com> wrote:
>>
>>>
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>>
>>> I suppose I could try it...
>>
>> Get a wirewound and make it into a MELF or get a bulk carbon comp and
>> snip and form the leads to make a standing, leaded MELF thingy.
>
> Looks like I need volume to absorb the energy, and on this board, that
> means I have to use all the height available. So I have to stand
> something up on end. Ugly but necessaty.
>
>>
>> 35 joules into a surface mount resistor even slowly would likely open
>> it up.
>
> 100 milliwatts for 350 seconds is 35 joules. An 0603 can do that.
>
>
>

How many do you need to make?
Can you stack surface mount resistors on top of each other?

Mikek

[Frank Miles]

On Thu, 23 May 2013 10:20:48 -0700, John Larkin wrote:

>>The worry with those is probably thermal fatigue. I like the lamp idea.
>
> We have had big wirewounds fail from pulsed-load cycling in NMR gradient
> drivers, without exceeding their peak rated power.

Did these WW's have welded connections, or swaged/caps? I've had very reliable
service from the welded types.

One example from eons ago when I was a student/tech in a University nuclear structure lab-
I was asked to repair an instrument that had been left on for weeks in a known failed
state (they didn't want to interrupt an experiment). The failure had caused a wirewound
to be driven so hard it glowed moderately bright red in normal room light. Once turned
off and disconnected from the circuit - the resistor was still within tolerance.

[John Larkin]

On Thu, 23 May 2013 22:16:07 +0000 (UTC), Frank Miles
<f...@u.washington.edu> wrote:

>On Thu, 23 May 2013 10:20:48 -0700, John Larkin wrote:
>
>>>The worry with those is probably thermal fatigue. I like the lamp idea.
>>
>> We have had big wirewounds fail from pulsed-load cycling in NMR gradient
>> drivers, without exceeding their peak rated power.
>
>Did these WW's have welded connections, or swaged/caps? I've had very reliable
>service from the welded types.

They were the big 250 watt military styles, bolt-down aluminum case,
screw studs on the ends for connections. The failure was usually a
short to the case.

We substituted this, works great:

https://dl.dropboxusercontent.com/u/53724080/Parts/Resistors/Welwyn.JPG

[tm]

"John Larkin" <jla...@highlandtechnology.com> wrote in message

news:rn5tp8ds77ni6trac...@4ax.com...

> On Thu, 23 May 2013 22:16:07 +0000 (UTC), Frank Miles
> <f...@u.washington.edu> wrote:
>
>>On Thu, 23 May 2013 10:20:48 -0700, John Larkin wrote:
>>
>>>>The worry with those is probably thermal fatigue. I like the lamp idea.
>>>
>>> We have had big wirewounds fail from pulsed-load cycling in NMR gradient
>>> drivers, without exceeding their peak rated power.
>>
>>Did these WW's have welded connections, or swaged/caps? I've had very
>>reliable
>>service from the welded types.
>
> They were the big 250 watt military styles, bolt-down aluminum case,
> screw studs on the ends for connections. The failure was usually a
> short to the case.
>
> We substituted this, works great:
>
> https://dl.dropboxusercontent.com/u/53724080/Parts/Resistors/Welwyn.JPG
>
>
> --
>
> John Larkin Highland Technology, Inc
>

You ought to TDR that thing :)

[George Herold]

On May 23, 3:35 pm, John Larkin <jlar...@highlandtechnology.com>
wrote:

Hmm, I don't know the 500 uohm/square number... per square inch of Cu?

I figured you'd need ~5 square inches of 1 oz. Cu to make a gram.

So maybe longer and wider (2 oz Cu)? Well unless you can figure on
the Cu dragging a bunch of the epoxy along with it.

George H.

[George Herold]

On May 23, 6:39 pm, John Larkin <jlar...@highlandtechnology.com>

wrote:
> On Thu, 23 May 2013 22:16:07 +0000 (UTC), Frank Miles
>
> <f...@u.washington.edu> wrote:
> >On Thu, 23 May 2013 10:20:48 -0700, John Larkin wrote:
>
> >>>The worry with those is probably thermal fatigue.  I like the lamp idea.
>
> >> We have had big wirewounds fail from pulsed-load cycling in NMR gradient
> >> drivers, without exceeding their peak rated power.
>
> >Did these WW's have welded connections, or swaged/caps?  I've had very reliable
> >service from the welded types.
>
> They were the big 250 watt military styles, bolt-down aluminum case,
> screw studs on the ends for connections. The failure was usually a
> short to the case.
>
> We substituted this, works great:
>
> https://dl.dropboxusercontent.com/u/53724080/Parts/Resistors/Welwyn.JPG

Ahh, can you use something like that for the current problem?
(too big?)

George H.

>
> --
>
> John Larkin         Highland Technology, Inc
>

> jlarkin at highlandtechnology dot comhttp://www.highlandtechnology.com

[Frank Miles]

On Thu, 23 May 2013 15:39:35 -0700, John Larkin wrote:

> On Thu, 23 May 2013 22:16:07 +0000 (UTC), Frank Miles
> <f...@u.washington.edu> wrote:
>
>>On Thu, 23 May 2013 10:20:48 -0700, John Larkin wrote:
>>
>>>>The worry with those is probably thermal fatigue. I like the lamp
>>>>idea.
>>>
>>> We have had big wirewounds fail from pulsed-load cycling in NMR
>>> gradient drivers, without exceeding their peak rated power.
>>
>>Did these WW's have welded connections, or swaged/caps? I've had very
>>reliable service from the welded types.
>
> They were the big 250 watt military styles, bolt-down aluminum case,
> screw studs on the ends for connections. The failure was usually a short
> to the case.

Hmmn... if it's what I'm remembering, those look really great but have a
crappy thermal pathway from element to case. I've seen them fail as you describe.

> We substituted this, works great:
>
> https://dl.dropboxusercontent.com/u/53724080/Parts/Resistors/Welwyn.JPG

That does look nice, at least for pulse power. For continuous you'd have
to have some good heat path.

[Jeff Liebermann]

On Wed, 22 May 2013 21:03:24 -0700, John Larkin
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:


>You can blow up resistors too!
>We're also designing a power mosfet exploding circuit.

I prefer to use electrolytics as weapons of mass destruction:
<http://802.11junk.com/jeffl/pics/drivel/slides/Blown%20Power%20Supply.html>

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Ralph Barone]

Vladimir Vassilevsky <nos...@nowhere.com> wrote:

> On 5/22/2013 6:54 PM, Joerg wrote:
>> John Larkin wrote:
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>>
>>> I suppose I could try it...
>>>
>>
>> Not into SMT but thru-hole. Ohmite has Joule ratings for some but I'd
>> contact them because 200msec is long:
>>
>> http://www.e-sonic.com/aboutus/cat/R/resistors.pdf
>> http://www.ohmite.com/
>>
>> Example: Page 141 bottom left
>>
>> Usually high pulse load calls for carbon resistor types.
>

> Joules assume more or less equilibrium state.
> For surge, I^2 x T rating is more appropriate.
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Designs
> www.abvolt.com

Yup, and if your pulse is fast enough, the heat sink doesn't matter. It's
all I^2*t, so it comes down to the volume of the current carrying portion,
its thermal capacity, and the maximum temperature it can withstand. Perhaps
a length of baling wire would work as well as anything else.

[John Larkin]

On Thu, 23 May 2013 23:46:26 +0000 (UTC), Frank Miles <f...@u.washington.edu>

The Welwyn things are thickfilm on porcelanized steel. They are slightly cupped
so that when you bolt them down, they hug the mounting surface. Neat.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

[John Larkin]

On Thu, 23 May 2013 16:33:29 -0700 (PDT), George Herold <ghe...@teachspin.com>
wrote:

Per square anything of 1 oz copper.

>
>I figured you'd need ~5 square inches of 1 oz. Cu to make a gram.
>

Yeah, 35 joules into a gram of copper is about an 88 deg C temperature spike.

>So maybe longer and wider (2 oz Cu)? Well unless you can figure on
>the Cu dragging a bunch of the epoxy along with it.

The epoxy would probably help, as would adjacent power or ground planes. So one
gram is probably OK. But 5 square inches, maybe doubled for traces+spaces, is a
lot.

--

John Larkin Highland Technology Inc

www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

[John Larkin]

On Thu, 23 May 2013 18:01:15 -0700, Jeff Liebermann <je...@cruzio.com> wrote:

>On Wed, 22 May 2013 21:03:24 -0700, John Larkin
><jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>
>>You can blow up resistors too!
>>We're also designing a power mosfet exploding circuit.
>
>I prefer to use electrolytics as weapons of mass destruction:
><http://802.11junk.com/jeffl/pics/drivel/slides/Blown%20Power%20Supply.html>

Looks like it lost a pie throwing contest.

[John Larkin]

With luck, thousands.

>Can you stack surface mount resistors on top of each other?

What looks practical is to stand a wirewound resistor, roughly 0.25 dia x 1 inch
long, on edge. Inelegant.

--

John Larkin Highland Technology Inc

www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

[John Larkin]

On Thu, 23 May 2013 12:41:53 -0700, John Larkin <jla...@highlandtechnology.com>
wrote:

>On Thu, 23 May 2013 20:13:11 +0200, "Dimitrij Klingbeil"
><nos...@no-address.com> wrote:
>
>>"John Larkin" <jla...@highlandtechnology.com> wrote in message
>>news:umlqp8tbebit3o1de...@4ax.com...
>>>
>>>
>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>> like to discharge about 35 joules of energy from some electrolytic
>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>> use a few 2512 or some such resistors.
>>
>>SMT resistors generally have poor pulse handling, AFAIK.
>>
>>You could try an SMT inductor however: find one with enough copper volume
>>and appropriate DC resistance, connect a diode in anti-parallel to quench
>>the ringing and there you have what amounts essentially to a big wirewound
>>resistor :)
>
>That is interesting. One could estimate the mass of the copper (or
>unwind it and weigh it) to compute peak temperature. The
>metal-to-insulator mass ratio of an inductor may well be better than a
>typical wirewound resistor.
>
>With 30,000 uF of electrolytics, I'd expect the Q to be so low that
>the diode wouldn't be necessary.
>
>Cool. Gotta think about that one.

Hey, copper is a pretty good RTD. Some clever circuit could dump the joules into
the coil and measure the temperature before it cools off.

--

John Larkin Highland Technology Inc

www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

[mi]

John Larkin <jla...@highlandtechnology.com> writes:

> Looks like I need volume to absorb the energy, and on this board, that
> means I have to use all the height available. So I have to stand
> something up on end. Ugly but necessaty.

An assembly house had once changed Ohmite OY-series 100ohm resistors to
carbon film resistors. The guy calibrating the device wondered why the
device made a strange *phut* sound on every measurement.

Opening the device revealed that the resistors shot out 20mm flames on each
measurement! Apparently the films did not like to 3kW peak / 20J load..

The Kanthal Globars you have quite a high maximum operating temperature!
--
Mikko OH2HVJ

[John Devereux]

I remember those green "vitreous enamelled"" wirewounds from my youth,
you could put them on car batteries and they would glow orange-hot,
melting the glass. You could see the coil through the glass.

Didn't seem to do them much harm at the time, but hardly a scientific
test!

<http://uk.farnell.com/welwyn/w22-4r7-ji/resistor-ww-7w-5-4r7/dp/9505016>

--

John Devereux

[George Herold]

On May 23, 11:07 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Thu, 23 May 2013 16:33:29 -0700 (PDT), George Herold <gher...@teachspin.com>

Got it.. so length/width is your 6,000. (for three ohms) If area is 5
sq-in. I get a width of 30 mil and a length of ~180" (ouch!)
For your long time scales you might guess you get twice the volume of
fiber glass dragged along... So 1/3 the area...

George H.

>
>
>
> >I figured you'd need ~5 square inches of 1 oz. Cu to make a gram.
>
> Yeah, 35 joules into a gram of copper is about an 88 deg C temperature spike.
>
> >So maybe longer and wider (2 oz Cu)?  Well unless you can figure on
> >the Cu dragging a bunch of the epoxy along with it.
>
> The epoxy would probably help, as would adjacent power or ground planes. So one
> gram is probably OK. But 5 square inches, maybe doubled for traces+spaces, is a
> lot.
>
> --
>

> John Larkin                  Highland Technology Incwww.highlandtechnology.com  jlarkin at highlandtechnology dot com

>
> Precision electronic instrumentation
> Picosecond-resolution Digital Delay and Pulse generators
> Custom timing and laser controllers
> Photonics and fiberoptic TTL data links
> VME  analog, thermocouple, LVDT, synchro, tachometer

> Multichannel arbitrary waveform generators- Hide quoted text -

[Phil Hobbs]

Why not mount it horizontally, but elevated, and put circuitry underneath?

[John Larkin]

This board is mainly paved over with tall stuff, caps and heatsinks
and connectors. I'd prefer to not cover up the little opamps and
things either, cause that makes them hard to probe. I do have a niche
in the corner, about 0.3 diameter, that's unused, and I could stand up
a wirewound there.

Packaging is 50% of electronics. Actual circuit design, the funnest
part, is maybe 10% if that.

--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com

http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators

Custom laser drivers and controllers

Photonics and fiberoptic TTL data links

[Phil Hobbs]

Yup. On the plus side, I just finished specifying a $100k digitizing
scope as the back end for a demo instrument. The immediate customer is
enthusiastic, partly I think because they'll get to keep the scope when
the demo is finished. ;)

[John Larkin]

On Fri, 24 May 2013 15:48:26 -0400, Phil Hobbs

Hmmm, comes out of a different departmental budget. Maybe all they
want is the scope!

We recently got a LeCroy (now Teledyne) 4-channel 7 GHz scope for
about $50K, Windows based. It does some cool things, when willing.

https://dl.dropboxusercontent.com/u/53724080/Gear/LeCrash.JPG

I guess you can run scope apps on it; haven't looked into that.

Really, it's more logical to get a knobless/screenless digitizer box
and connect it to a PC.

[John Fields]

On Thu, 23 May 2013 12:28:13 -0400, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>On 05/23/2013 11:03 AM, John Larkin wrote:
>> On Thu, 23 May 2013 03:51:11 -0500, John Fields <jfi...@austininstruments.com>
>> wrote:
>>
>>> On Wed, 22 May 2013 20:59:53 -0700, John Larkin
>>> <jjla...@highNOTlandTHIStechnologyPART.com> wrote:

>>>
>>>> On Wed, 22 May 2013 22:16:10 -0400, "tm" <No_on...@white-house.gov> wrote:
>>>>
>>>>>
>>>>> "John Larkin" <jla...@highlandtechnology.com> wrote in message

>>>>> news:6snqp8h4b8fsq367l...@4ax.com...
>>>>>> On Wed, 22 May 2013 16:54:10 -0700, Joerg <inv...@invalid.invalid>
>>>>>> wrote:

>>>>>>
>>>>>>> John Larkin wrote:
>>>>>>>>
>>>>>>>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>>>>>>>> like to discharge about 35 joules of energy from some electrolytic
>>>>>>>> caps, in a couple tenths of a second maybe, and it would be cool to
>>>>>>>> use a few 2512 or some such resistors.
>>>>>>>>
>>>>>>>> I suppose I could try it...
>>>>>>>>
>>>>>>>

>>>>>>> Not into SMT but thru-hole. Ohmite has Joule ratings for some but I'd
>>>>>>> contact them because 200msec is long:
>>>>>>>
>>>>>>> http://www.e-sonic.com/aboutus/cat/R/resistors.pdf
>>>>>>> http://www.ohmite.com/
>>>>>>>
>>>>>>> Example: Page 141 bottom left
>>>>>>>
>>>>>>> Usually high pulse load calls for carbon resistor types.
>>>>>>

>>>>>> Test: 2512, thickfilm, 0.2 ohms 1%, soldered to lots of copper.
>>>>>>
>>>>>> Dumped 10,000 uF at 10 volts, 0.5 joules.
>>>>>>
>>>>>> Blew it open first try. Guess I'll try some wirewounds.

>>>>>>
>>>>>>
>>>>>> --
>>>>>>
>>>>>> John Larkin Highland Technology, Inc
>>>>>

>>>>> Why don't you start out on the low end and see where it fails?
>>>>>
>>>>> tm
>>>>
>>>> Tomorrow maybe. Had to leave at 5:30.
>>>>
>>>> Higher resistor values might do better, but it looks like there's no way I'm
>>>> going to dump 35 or so joules into any reasonable array of regular surface-mount
>>>> resistors.
>>>>
>>>> I may have to stand up a leaded wirewound part, roughly 0.25" dia x 1" long.
>>>> Inelegant.
>>>
>>> ---
>>> http://www.globar.com/ec/bulk-ceramic-resistors
>>
>> Yeah, I guess the summary is that the heat has to be generated all through the
>> bulk of the resistive material. Most insulators conduct heat slowly enough that
>> the element gets all the energy initially, so it vaporizes. Even most wirewound
>> resistors make the heat in a small fraction of the total volume.
>>
>> I might be able to use their 234SP, standing up. It's rated 30 joules for 10
>> milisecond pulses, apparently more for longer pulses.
>>
>> http://www.globar.com/ec/bulk-ceramic-resistors/axial-leaded-resistors.html
>>
>> If I discharge 30,000 uF through, say, 5 ohms, that's a 150 millisecond tau. A
>> carbon comp with that diameter+length might work too, if one existed.
>>
>> Here's the board... this is a dummy layout, just pushing parts around and seeing
>> what might fit.
>>
>> https://dl.dropboxusercontent.com/u/53724080/PCBs/D100_pads.jpg
>>
>> That resistor might fit into the upper-left corner.
>>
>> I think the Globar parts are carborundum, silicon carbide, which is hard to
>> vaporize.
>>
>> Thanks

>
>The worry with those is probably thermal fatigue. I like the lamp idea.

> A Maglite bulb might be about right.
>
>Cheers
>
>Phil Hobbs

---
Since a Maglite bulb's tungsten filament is subjected to severe length
as well as diametral changes during its excitation, - depending on its
grain structure after rolling - and is constrained by mechanical
supports, I'd expect that thermal fatigue would cause it to fail more
often than the more or less innocuous stretch and shrink of a bulk
silicon carbide resistor.

I haven't looked up the TCEs of tungsten or silicon carbide, so it's
all just conjecture, so far.

Do you want to sally forth?

--
JF

[josephkk]

Ya. I saw the photo, and they do look cool. But the pulse power to
continuous power handling capability is not as good as metal film, metal
foil, wirewound (includes foil wound), or carbon composition resistors.

?-)

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Wed, 22 May 2013 21:03:24 -0700, John Larkin
> <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>
>>You can blow up resistors too!
>>We're also designing a power mosfet exploding circuit.
>
> I prefer to use electrolytics as weapons of mass destruction:
> <http://802.11junk.com/jeffl/pics/drivel/slides/Blown%20Power%20Supply.html>

Ha- there's a daewoo IC there. I forgot about them. Apparently they
collapsed in 1999.

[Jeff Liebermann]

On Sat, 25 May 2013 03:50:18 +0000 (UTC), Cydrome Leader
<pres...@MUNGEpanix.com> wrote:

>Jeff Liebermann <je...@cruzio.com> wrote:
>> On Wed, 22 May 2013 21:03:24 -0700, John Larkin
>> <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>>
>>
>>>You can blow up resistors too!
>>>We're also designing a power mosfet exploding circuit.
>>
>> I prefer to use electrolytics as weapons of mass destruction:
>> <http://802.11junk.com/jeffl/pics/drivel/slides/Blown%20Power%20Supply.html>

Note that the entire mess came from the contents of two small
electrolytics. The "cans" are the purple and black things near the
middle of the picture.

>Ha- there's a daewoo IC there. I forgot about them. Apparently they
>collapsed in 1999.

Daewoo came back from the dead in about 2006:
<http://www.daewooelecusa.com>
and is now part of the Dongbu group:
<http://www.dongbu.com/eng/main/main.asp>
Incidentally, Daewoo means "Woo the great". Woo was the name of
company founder. More in the same style:
<http://802.11junk.com/jeffl/pics/drivel/slides/dae-young.html>
Yes, the hard drive died young.

[Phil Hobbs]

A tungsten bulb's filament is free-standing, so there's not much shear
stress to cause cracking and fatigue. Also the annealing temperature of
tungsten is below 2000K iirc, so the filament itself is always in the
fully-annealed state, so no work-hardening is expected.

Something like a coil of wire hanging on long skinny supports is about
the best structure imaginable for resisting thermal fatigue.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203

Briarcliff Manor NY 10510 USA
+1 845 480 2058

[Phil Hobbs]

If the scope runs Windows, I agree with you. There's a trend away from
that at the moment (hurrah), so it may soon be possible to have a scope
that you can hang on a network and not have to worry about.

I'd be quite unlikely to spend big bux for a low-volume digitizer box
that didn't have a display attached. I can just imagine what finding
drivers for something like that would be like in, say, 10 years' time.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203

Briarcliff Manor NY 10510 USA
+1 845 480 2058

[John Fields]

---
"Long skinny supports" certainly doesn't apply to the Maglite lamps
you've cited, and one would expect that, since the points of
attachment of the filament to the electrodes run much cooler than the
radiating parts of the filament, the mechanical expansion of the
filament during heating will stress the joint in compression and
shear, causing work-hardening and, ultimately, failure to occur at the
joint.

Then there's also what happens when the flashlight is turned off...

--
JF

[John Fields]

---
If you have drivers for it now, why wouldn't they work 10 years from
now?

After all, VGA is still viable.


--
JF

[Jeroen]

On 2013-05-25 20:51, Phil Hobbs wrote:
> John Larkin wrote:
[.....]

>> Really, it's more logical to get a knobless/screenless digitizer box
>> and connect it to a PC.
>
> If the scope runs Windows, I agree with you. There's a trend away from
> that at the moment (hurrah), so it may soon be possible to have a scope
> that you can hang on a network and not have to worry about.
>
> I'd be quite unlikely to spend big bux for a low-volume digitizer box
> that didn't have a display attached. I can just imagine what finding
> drivers for something like that would be like in, say, 10 years' time.

Drivers? Who needs drivers? You'd control the thing using an ordinary
web browser.

Jeroen Belleman

[Phil Hobbs]

Why not do a study of the fatigue properties of light bulbs, and tell us
how they perform?

[John Fields]

On Sat, 25 May 2013 17:34:09 -0400, Phil Hobbs

<pcdhSpamM...@electrooptical.net> wrote:

>On 5/25/2013 5:06 PM, John Fields wrote:
>> On Sat, 25 May 2013 14:47:48 -0400, Phil Hobbs
>> <pcdhSpamM...@electrooptical.net> wrote:
>>
>>
>>> A tungsten bulb's filament is free-standing, so there's not much shear
>>> stress to cause cracking and fatigue. Also the annealing temperature of
>>> tungsten is below 2000K iirc, so the filament itself is always in the
>>> fully-annealed state, so no work-hardening is expected.
>>>
>>> Something like a coil of wire hanging on long skinny supports is about
>>> the best structure imaginable for resisting thermal fatigue.
>>
>> ---
>> "Long skinny supports" certainly doesn't apply to the Maglite lamps
>> you've cited, and one would expect that, since the points of
>> attachment of the filament to the electrodes run much cooler than the
>> radiating parts of the filament, the mechanical expansion of the
>> filament during heating will stress the joint in compression and
>> shear, causing work-hardening and, ultimately, failure to occur at the
>> joint.
>>
>> Then there's also what happens when the flashlight is turned off...
>>
>
>Why not do a study of the fatigue properties of light bulbs, and tell us
>how they perform?

---
Since you're the one who broached the subject, and it's been
contested, it seems to me that you're the one upon whom the onus of
proof falls.


--
JF

[Phil Hobbs]

Why? Your deciding (for reasons of your own) to go snapping round my
ankles doesn't obligate me at all. If you don't like the idea, don't
use it.

[Jasen Betts]

X-Face: ?)Aw4rXwN5u0~$nqKj`xPz>xHCwgi^q+^?Ri*+R(&uv2=E1Q0Zk(>h!~o2ID@6{uf8s;a+M[5[U[QT7xFN%^gR"=tuJw%TXXR'Fp~W;(T"1(739R%m0Yyyv*gkGoPA.$b,D.w:z+<'"=-lVT?6{T?=R^:W5g|E2#EhjKCa+nt":4b}dU7GYB*HBxn&Td$@f%.kl^:7X8rQWd[NTc"P"u6nkisze/Q;8"9Z{peQF,w)7UjV$c|RO/mQW/NMgWfr5*$-Z%u46"/00mx-,\R'fLPe.)^

yeah, you'll probably still be able to run windows 8 in 10 years time.

--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---

[Phil Hobbs]

Jasen Betts wrote:
>
> X-Face: ?)Aw4rXwN5u0~$nqKj`xPz>xHCwgi^q+^?Ri*+R(&uv2=E1Q0Zk(>h!~o2ID@6{uf8s;a+M[5[U[QT7xFN%^gR"=tuJw%TXXR'Fp~W;(T"1(739R%m0Yyyv*gkGoPA.$b,D.w:z+<'"=-lVT?6{T?=R^:W5g|E2#EhjKCa+nt":4b}dU7GYB*HBxn&Td$@f%.kl^:7X8rQWd[NTc"P"u6nkisze/Q;8"9Z{peQF,w)7UjV$c|RO/mQW/NMgWfr5*$-Z%u46"/00mx-,\R'fLPe.)^
>
> On 2013-05-25, John Fields <jfi...@austininstruments.com> wrote:
> > On Sat, 25 May 2013 14:51:28 -0400, Phil Hobbs
> ><pcdhSpamM...@electrooptical.net> wrote:
> >
> >
> >>I'd be quite unlikely to spend big bux for a low-volume digitizer box
> >>that didn't have a display attached. I can just imagine what finding
> >>drivers for something like that would be like in, say, 10 years' time.
> >
> > ---
> > If you have drivers for it now, why wouldn't they work 10 years from
> > now?
> >
>
> yeah, you'll probably still be able to run windows 8 in 10 years time.
>

The issue is, can you configure a newish computer to run the old
drivers? Maybe yes, maybe no. A dozen years ago, the latest and
greatest MS OS was Win 2k. Can you run those drivers today?

Hardware is changing more rapidly now than 10 years ago, and the changes
are not in Microsoft's favour. Also, attacks always get better, never
worse, so even if you stick with antique hardware, who knows how long
one will be able to connect such a computer to the network?

Some nice self-contained thing with a non-Windows OS in write-protected
flash memory is the ticket, at least for my money.

[Jamie]

Phil Hobbs wrote:

> Jasen Betts wrote:
>
>>X-Face: ?)Aw4rXwN5u0~$nqKj`xPz>xHCwgi^q+^?Ri*+R(&uv2=E1Q0Zk(>h!~o2ID@6{uf8s;a+M[5[U[QT7xFN%^gR"=tuJw%TXXR'Fp~W;(T"1(739R%m0Yyyv*gkGoPA.$b,D.w:z+<'"=-lVT?6{T?=R^:W5g|E2#EhjKCa+nt":4b}dU7GYB*HBxn&Td$@f%.kl^:7X8rQWd[NTc"P"u6nkisze/Q;8"9Z{peQF,w)7UjV$c|RO/mQW/NMgWfr5*$-Z%u46"/00mx-,\R'fLPe.)^
>>
>>On 2013-05-25, John Fields <jfi...@austininstruments.com> wrote:
>>
>>>On Sat, 25 May 2013 14:51:28 -0400, Phil Hobbs
>>><pcdhSpamM...@electrooptical.net> wrote:
>>>
>>>
>>>
>>>>I'd be quite unlikely to spend big bux for a low-volume digitizer box
>>>>that didn't have a display attached. I can just imagine what finding
>>>>drivers for something like that would be like in, say, 10 years' time.
>>>
>>>---
>>>If you have drivers for it now, why wouldn't they work 10 years from
>>>now?
>>>
>>
>>yeah, you'll probably still be able to run windows 8 in 10 years time.
>>
>
>
> The issue is, can you configure a newish computer to run the old
> drivers? Maybe yes, maybe no. A dozen years ago, the latest and
> greatest MS OS was Win 2k. Can you run those drivers today?
>
> Hardware is changing more rapidly now than 10 years ago, and the changes
> are not in Microsoft's favour. Also, attacks always get better, never
> worse, so even if you stick with antique hardware, who knows how long
> one will be able to connect such a computer to the network?
>
> Some nice self-contained thing with a non-Windows OS in write-protected
> flash memory is the ticket, at least for my money.
>
> Cheers
>
> Phil Hobbs
>

Yes, a jumper is always the best way!

Jamie

[Joerg]

Jasen Betts wrote:
> X-Face: ?)Aw4rXwN5u0~$nqKj`xPz>xHCwgi^q+^?Ri*+R(&uv2=E1Q0Zk(>h!~o2ID@6{uf8s;a+M[5[U[QT7xFN%^gR"=tuJw%TXXR'Fp~W;(T"1(739R%m0Yyyv*gkGoPA.$b,D.w:z+<'"=-lVT?6{T?=R^:W5g|E2#EhjKCa+nt":4b}dU7GYB*HBxn&Td$@f%.kl^:7X8rQWd[NTc"P"u6nkisze/Q;8"9Z{peQF,w)7UjV$c|RO/mQW/NMgWfr5*$-Z%u46"/00mx-,\R'fLPe.)^
>
> On 2013-05-25, John Fields <jfi...@austininstruments.com> wrote:
>> On Sat, 25 May 2013 14:51:28 -0400, Phil Hobbs
>> <pcdhSpamM...@electrooptical.net> wrote:
>>
>>
>>> I'd be quite unlikely to spend big bux for a low-volume digitizer box
>>> that didn't have a display attached. I can just imagine what finding
>>> drivers for something like that would be like in, say, 10 years' time.
>> ---
>> If you have drivers for it now, why wouldn't they work 10 years from
>> now?
>>
>
> yeah, you'll probably still be able to run windows 8 in 10 years time.
>

Until a few years ago I ran a printer from the early 90's. The only
reason I stopped was that it began to fall apart. Then there's my logic
analyzer from the mid-80's. Operates through RS232, no problems either.
Although I haven't needed it in years.

--
Regards, Joerg

http://www.analogconsultants.com/

[Phil Hobbs]

Good luck to the malware writers infecting a boat anchor over GPIB or
RS232!

[John Fields]

On Sat, 25 May 2013 19:35:06 -0400, Phil Hobbs

---
Hardly snapping round your ankles; I was merely pointing out an
inconsistency in your earlier post, to which you took umbrage and
decided to engage your Larkin emulator.

--
JF

[Robert Baer]

You give such deLIGHTful examples..

[rickman]

I worked at a place that designed military radios. We were adding an
FPGA to provide an interface for a special app and they wanted to be
able to download new FPGA bitstreams in the factory or repair depot.
Security was a MAJOR issue, so I recommended a jumper. The software
people overrode that and made it a software accessible something or
other using a "key". Obviously that isn't as secure, but there was no
point in arguing. They didn't want to be in a position where they had
to depend on a hardware person to tell them which jumper or something
silly like that. Heck, if the jumper was a problem in the lab, just
always keep it on. Otherwise why take the risk that the "key" could be
hacked/copied/predicted... etc. It was one key for *all* units, so if
it was compromised the entire set of units was compromised.

--

Rick

[rickman]

On 5/23/2013 1:10 PM, lang...@fonz.dk wrote:
> On May 23, 1:42 am, John Larkin<jlar...@highlandtechnology.com>

> wrote:
>> Has anybody dumped a lot of energy into surfmount resistors, fast? I'd
>> like to discharge about 35 joules of energy from some electrolytic
>> caps, in a couple tenths of a second maybe, and it would be cool to
>> use a few 2512 or some such resistors.
>>
>> I suppose I could try it...
>>
>

> these say 100J : http://www.ohmite.com/cat/res_tp.pdf

I think this is a bit larger than he wanted, but otherwise seems to be
just the ticket! Odd designing a circuit and even the layout before
knowing what part you will be using.

--

Rick

[John Fields]

---
:-)

--
JF

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Sat, 25 May 2013 03:50:18 +0000 (UTC), Cydrome Leader
> <pres...@MUNGEpanix.com> wrote:
>
>>Jeff Liebermann <je...@cruzio.com> wrote:
>>> On Wed, 22 May 2013 21:03:24 -0700, John Larkin
>>> <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>>>
>>>
>>>>You can blow up resistors too!
>>>>We're also designing a power mosfet exploding circuit.
>>>
>>> I prefer to use electrolytics as weapons of mass destruction:
>>> <http://802.11junk.com/jeffl/pics/drivel/slides/Blown%20Power%20Supply.html>
>
> Note that the entire mess came from the contents of two small
> electrolytics. The "cans" are the purple and black things near the
> middle of the picture.
>
>>Ha- there's a daewoo IC there. I forgot about them. Apparently they
>>collapsed in 1999.
>
> Daewoo came back from the dead in about 2006:
> <http://www.daewooelecusa.com>
> and is now part of the Dongbu group:
> <http://www.dongbu.com/eng/main/main.asp>
> Incidentally, Daewoo means "Woo the great". Woo was the name of
> company founder. More in the same style:
> <http://802.11junk.com/jeffl/pics/drivel/slides/dae-young.html>
> Yes, the hard drive died young.

ha, even the label on that drive looks cheap. The crappiest drives made
since the 1980s I ever saw were "JTS" and from India. The excitement in
openening a stryofoam tray of those drives was finding on that would last
long enough to survive an installation of windows.

[Cydrome Leader]

mi <mi...@labserve1.i-did-not-set--mail-host-address--so-tickle-me> wrote:
> Jeff Liebermann <je...@cruzio.com> writes:
>
>> kg = 1 / (70 * 1050) = 0.0136 grams
>
> Make that 0.0136 kg = 13.6 grams. 250 resistors should be enough.
>
> If the dumping is done relatively infrequently, the heat capacity and
> pulse power capacity are the limiting factors, the smallest solution is
> probably a few carbon/ceramic composition resistors like Ohmite OX/OY series.

How about a nice MOV? Put a window in the enclosure so the flames can be
used as some sort of "sevice" indicator.

[Cydrome Leader]

Once you remove the dark, cluttery buttons, the actual waveform looks
like it was copy and pasted from an a cell phone.

[Jeff Liebermann]

On Wed, 29 May 2013 17:33:18 +0000 (UTC), Cydrome Leader

<http://en.wikipedia.org/wiki/JT_Storage>

<http://en.wikipedia.org/wiki/List_of_defunct_hard_disk_manufacturers>
I think I've used or seen drives from about half of these
manufacturers.

I've also had "dead out of the box" failures. I purchased spare
drives when I setup a RAID 0+1 array of 5 drives. I think there were
3 spare drives. When the operating drives started to show signs of
impending doom, I replaced the failing drive with a new identical
drive from the spares collection. A few days later, another of the
running drives started to show symptoms, which was also replaced by
one of the spare new drives. Then the first replacement started to
fail, followed by another of the running drives. Obviously, so many
failures, including one new drive, must have a common cause. I wasted
considerable time chasing power problems and replacing the Mylex RAID
controller. I eventually determined that the drives really were the
problem and that the life expectancy of a running drive and one that
had been languishing in the box, were identical. I could not find the
"post warranty destruct timer" device on the PCB. All the drives were
replaced with a different brand, which worked reliably for at least 5
years, when my situation changed and I no longer serviced the account.

Sometimes I wonder if it's like the bulging electrolytics problem.
Once the manufacturers find a mechanism that produces a failure
immediately after the warranty period is over, there's a financial
incentive to continue doing it the same way. I know it's possible to
have a drive run nearly forever. I have a 1986(?) vintage Conner
Peripherals 1GB drive in the ancient Xenix server in my palatial
office, that has been running continuously for about 25 years with no
evidence of impending failure. I would gladly trade half or more of
the drive capacity for a major increase in reliability. Better life
seems to be something customers want. When I ordered "enhanced
reliability" drives from Dell about 4 years ago, which turned out to
be Samung drives, they all died after about 1 year of intermittent
service.

[John Devereux]

Jeff Liebermann <je...@cruzio.com> writes:

> On Wed, 29 May 2013 17:33:18 +0000 (UTC), Cydrome Leader
> <pres...@MUNGEpanix.com> wrote:
>
>>Jeff Liebermann <je...@cruzio.com> wrote:
>
>>> <http://802.11junk.com/jeffl/pics/drivel/slides/dae-young.html>
>>> Yes, the hard drive died young.
>
>>ha, even the label on that drive looks cheap. The crappiest drives made
>>since the 1980s I ever saw were "JTS" and from India. The excitement in
>>openening a stryofoam tray of those drives was finding on that would last
>>long enough to survive an installation of windows.
>
> <http://en.wikipedia.org/wiki/JT_Storage>
>
> <http://en.wikipedia.org/wiki/List_of_defunct_hard_disk_manufacturers>
> I think I've used or seen drives from about half of these
> manufacturers.
>

[...]

> Sometimes I wonder if it's like the bulging electrolytics problem.
> Once the manufacturers find a mechanism that produces a failure
> immediately after the warranty period is over, there's a financial
> incentive to continue doing it the same way.

Maybe, but drives are pretty interchangeable so there is a reputation to
protect I think. Recently I took one apart that was a couple years old,
out of curiousity. There very clever things in there, beautifully
engineered and optimised, must be really state of the art manufacturing
techniques. Pity they break so often...

> I know it's possible to have a drive run nearly forever. I have a
> 1986(?) vintage Conner Peripherals 1GB drive in the ancient Xenix
> server in my palatial office, that has been running continuously for
> about 25 years with no evidence of impending failure. I would gladly
> trade half or more of the drive capacity for a major increase in
> reliability. Better life seems to be something customers want. When
> I ordered "enhanced reliability" drives from Dell about 4 years ago,
> which turned out to be Samung drives, they all died after about 1 year
> of intermittent service.

Similar here, I now assume "enhanced reliability" is just an extended
warranty paid for by the cost bump.

--

John Devereux

[Joe Gwinn]

In article <87sj14o...@devereux.me.uk>, John Devereux

I think that the 10,000 RPM "Enterprise" disks intended for servers are
different. I fitted one to a desktop Mac some years ago. What a
difference in performance it made! And you could tell it was there by
the deep hum when it ran.

Joe Gwinn