This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John

On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.


You have a copper workbench?????


;-)
Rich

John Larkin wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.


Great. 92% is pretty cool. I'd still try it with a CD40106. Might have
to parallel a bit or use a npn/pnp to get to 92% but who knows. I got
pretty close to 90% on one but that had to operate from Vbat (9V,
allowed down to 6V) to around 60V. At 12V input the 40106 might have
enough oomph on its own. And has a built-in resistor :-)

--
Regards, Joerg

http://www.analogconsultants.com

John Larkin wrote:
This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John

I used to do converters like that all the time, and as you noted, with a little
tweaking, and good load stability, they are quite efficient. I had to stop
building things like that when FCC certification became the norm... The RFI
spectrum is kind of hard to control.

-Chuck

Chuck Harris wrote:
John Larkin wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.
Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John


I used to do converters like that all the time, and as you noted, with a
little
tweaking, and good load stability, they are quite efficient. I had to stop
building things like that when FCC certification became the norm... The RFI
spectrum is kind of hard to control.


That's where using a CD40106 comes in handy. You can take one of the
free inverters as a 2nd oscillator and inject a little dithering. I like
the French word for it, estompage.

Of course the EMI guys frown upon that and I try to remain under without
dither.

--
Regards, Joerg

http://www.analogconsultants.com

"John Larkin" wrote in message
...
This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John





Nice, TI has some tiny(sot-23) 1 cap charge pumps, nice and neat. But only
~60ma and 5V max.
http://focus.ti.com/paramsearch/docs...ramCriteria=no


Cheers

On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John



OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.

John

John Larkin wrote:

On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:


This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John




OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.


Why not use a ceramic cap in series with a small resistance? That's the
common method to obtain a well defined ESR. I'd never use tantalums. But
I also do not use LDOs anymore so the problem rarely arises. Never had a
switcher going berserk though but I usually keep them in discontinuous
mode at all times and avoid getting anywhere close to a RHP zero issue.

I'd rather spring for a little larger core and not hold my breath
whether or not somebody in the field connects a weird load. Right now it
seems you'll be in full control of the load but some day that could
change. You'll be sipping pinacoladas next to your Learjet on Larkin
Island and some guy in your old company thinks "Hey, let's use John's
old switcher for this board!"

--
Regards, Joerg

http://www.analogconsultants.com

On Fri, 20 Jul 2007 13:43:24 -0700, Joerg
wrote:

John Larkin wrote:

On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:


This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John




OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.


Why not use a ceramic cap in series with a small resistance? That's the
common method to obtain a well defined ESR.

I guess I could, but it would take much more area, and I need to keep
ripple down, too. Maybe I'll try and see how much R it takes to keep
it sane.

I'd never use tantalums.

Derated 2:1 on voltage, all I'll need is a little luck!

But
I also do not use LDOs anymore so the problem rarely arises. Never had a
switcher going berserk though but I usually keep them in discontinuous
mode at all times and avoid getting anywhere close to a RHP zero issue.

This is going into a DDS frequency synthesizer, and I'm not
enthusiastic about having 20 volts p-p snapoff ringing, roughly 1 MHz,
a few inches from the output amps. Snubbing would wreck efficiency.
This version runs in continuous mode from 32 mA to 1 amp, so my idle
load will keep it continuous.


I'd rather spring for a little larger core and not hold my breath
whether or not somebody in the field connects a weird load.

I'm trying to do an 8-channel 32 MHz DDS synthesizer (4 actual
outputs, four hidden modulation sources) with AM/FM/PM mods, summing,
channel sync, arbitrary waveforms, RS232, Ethernet, phase locking, 20
v p-p outputs, 32-bit uP, and some neat colored LEDs, in 16 square
inches.

Right now it
seems you'll be in full control of the load but some day that could
change. You'll be sipping pinacoladas next to your Learjet on Larkin
Island and some guy in your old company thinks "Hey, let's use John's
old switcher for this board!"

Serves them right, arrogant young puppies!

John

John Larkin wrote:

On Fri, 20 Jul 2007 13:43:24 -0700, Joerg
wrote:


John Larkin wrote:


On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:



This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John




OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.


Why not use a ceramic cap in series with a small resistance? That's the
common method to obtain a well defined ESR.


I guess I could, but it would take much more area, and I need to keep
ripple down, too. Maybe I'll try and see how much R it takes to keep
it sane.


For ripple it doesn't really matter much whether the ESR is inside or
outside the cap ;-)


I'd never use tantalums.


Derated 2:1 on voltage, all I'll need is a little luck!


A whole lotta luck I'd say. Some fine day the manufacturer "improves"
the capacitor but thinks that since its ESR is better the spec update
can wait until Jane is back from maternity leave. Suddenly your
switchers are on the edge and then the first hickups are reported from
the field. Doesn't have to happen, but I've seen it.


But
I also do not use LDOs anymore so the problem rarely arises. Never had a
switcher going berserk though but I usually keep them in discontinuous
mode at all times and avoid getting anywhere close to a RHP zero issue.


This is going into a DDS frequency synthesizer, and I'm not
enthusiastic about having 20 volts p-p snapoff ringing, roughly 1 MHz,
a few inches from the output amps. Snubbing would wreck efficiency.
This version runs in continuous mode from 32 mA to 1 amp, so my idle
load will keep it continuous.


Then you have to. But I'd probably do that using a push-pull converter
with an inductor after the rectifier. Usually those talk less.


I'd rather spring for a little larger core and not hold my breath
whether or not somebody in the field connects a weird load.


I'm trying to do an 8-channel 32 MHz DDS synthesizer (4 actual
outputs, four hidden modulation sources) with AM/FM/PM mods, summing,
channel sync, arbitrary waveforms, RS232, Ethernet, phase locking, 20
v p-p outputs, 32-bit uP, and some neat colored LEDs, in 16 square
inches.


That sure explains the need for efficiency, assuming liquid cooling is
not an option.


Right now it
seems you'll be in full control of the load but some day that could
change. You'll be sipping pinacoladas next to your Learjet on Larkin
Island and some guy in your old company thinks "Hey, let's use John's
old switcher for this board!"


Serves them right, arrogant young puppies!


--
Regards, Joerg

http://www.analogconsultants.com

On Sat, 21 Jul 2007 18:19:52 -0400, PeteS
wrote:

John Larkin wrote:
On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John



OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.

John


The ESR problem is one I solved by using a pair of tants (to reduce the
surge on each) and a parallel small ceramic in series with ~1 ohm
resistor to maintain the ESR at extended temps (where tants can't be
said to have the best characteristics). Another type of cap I used
successfully in this area was Niobium Oxide.

Cheers

PeteS

Conventional dry tants seem to have pretty flat esr versus temperature
(whereas aluminums and wet-slug tants go nuts below 0C). They'd be
ideal for my little circuit, and for lots of IC LDO's and switchers,
except for the surge current failure mechanism. And it's annoying to
add resistors specifically to wreck the cap impedance.

Maybe I can do something fairly simple to soft-start my inverter, to
keep the cap surge current down. That would make me feel a little
better about using tants.

Dumb idea: a series resistor that is shorted out by a mosfet after the
supply starts up.

Anyhow, we've learned to read voltage regulator datasheets *very*
carefully for plainly stated, or carefully hidden, requirements for
output cap ESR's. Try an LM337 with ceramics some time!

John

John Larkin wrote:
On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John



OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.

John


The ESR problem is one I solved by using a pair of tants (to reduce the
surge on each) and a parallel small ceramic in series with ~1 ohm
resistor to maintain the ESR at extended temps (where tants can't be
said to have the best characteristics). Another type of cap I used
successfully in this area was Niobium Oxide.

Cheers

PeteS

John Larkin wrote:
On Sat, 21 Jul 2007 18:19:52 -0400, PeteS
wrote:

John Larkin wrote:
On Thu, 19 Jul 2007 11:27:55 -0700, John Larkin
wrote:

This circuit is back! I'm getting 92% efficiency converting +12 to -12
at 6.5 watts out, and the regulation loop seems to work. In fact, the
whole thing worked first try. The parts are cheap... the fet is 23
cents and the LM5112 is 50 cents at 1K.

The series gate resistor can be tweaked to essentially snub the small
switching rings, at some cost in efficiency, but then snubbing always
costs efficiency.

Now I've got to explore the control space, stability and load
transients at various loads. It will go discontinuous at light loads,
so the dynamics will change. Control-wise, it behaves sort of like a
hysteretic buck converter.

John


OK, I have the standard dilemma, common with most LDOs, negative
regulators, and many switchers:

It's unstable with ceramic output caps; ESR is too low. Stabilizing
the loop wrecks load transient response.

It's fine with aluminum caps, but aluminums go to hell below 0 degrees
C.

Polymer alums are rare at 12 volts, and have super-low ESRs, so may
oscillate anyhow.

It's great with tantalums, between explosions.

It looks like the compromise is to reduce loop gain about 2:1 (bigger
feedback resistor), and make the output cap from a 47 uF, 25 volt
tantalum paralleled with a 10 uF ceramic, and hope the tantalum
explodes infrequently.

John

The ESR problem is one I solved by using a pair of tants (to reduce the
surge on each) and a parallel small ceramic in series with ~1 ohm
resistor to maintain the ESR at extended temps (where tants can't be
said to have the best characteristics). Another type of cap I used
successfully in this area was Niobium Oxide.

Cheers

PeteS

Conventional dry tants seem to have pretty flat esr versus temperature
(whereas aluminums and wet-slug tants go nuts below 0C). They'd be
ideal for my little circuit, and for lots of IC LDO's and switchers,
except for the surge current failure mechanism. And it's annoying to
add resistors specifically to wreck the cap impedance.

Maybe I can do something fairly simple to soft-start my inverter, to
keep the cap surge current down. That would make me feel a little
better about using tants.

Dumb idea: a series resistor that is shorted out by a mosfet after the
supply starts up.

Anyhow, we've learned to read voltage regulator datasheets *very*
carefully for plainly stated, or carefully hidden, requirements for
output cap ESR's. Try an LM337 with ceramics some time!

John


Soft starting the supply is just about always a good idea. The method of
choice in integrated devices is a small (a few microamps) current source
charging an external cap - choose the cap for the start time required,
although this has side effects in Linear tech devices (the overcurrent
operating time is sensitive to this value). Soft starting by controlling
the output ramp rather than the output effective resistance might be
simpler as it does not have to switch in and out, although a small
resistor and mosfet may well solve the issue. A pretty simple setup
would do it, although you need to be careful of the body diode.

As to being careful of datasheets, I've inherited sufficient marginal or
downright 'will not work' supplies because the details in the
datasheet(s) were not properly attended to. The LM337 issue is
interesting - they were invented in a time when esr values of a few
milliohms were not even a pipe dream, at least for typical power supply
value caps. Just goes to show that 'newer and better' isn't always

It can sometimes take quite some time to choose the right parts for a
supply that has to be stable across a wide range of Vin/Vout and zero
output current to a large output current; I went to the extent of
writing some simple utilities to plug the numbers in and get simple bode
plots in excel to at least get me in the ballpark.

Cheers

PeteS

It's great with tantalums, between explosions.

LOL!

Sorry,just had to laugh at that one..
I friggin hate tantalums,for that very reason.

On Thu, 26 Jul 2007 01:02:21 -0700, PhattyMo
wrote:



It's great with tantalums, between explosions.

LOL!

Sorry,just had to laugh at that one..
I friggin hate tantalums,for that very reason.

It's like with Saabs: great cars to drive, between fires.

John

"John Larkin" wrote in
message

It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there must be
some parameter that's being pushed. Voltage not derated enough?


--

Reply in group, but if emailing add another
zero, and remove the last word.

On Fri, 27 Jul 2007 16:03:35 -0400, "Tom Del Rosso"
wrote:

"John Larkin" wrote in
message

It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there must be
some parameter that's being pushed. Voltage not derated enough?

High currents (ie, high dV/dT) causes tiny little sintered projections
to heat up. Tantalum metal is fuel and the MnO2 electrode is the
oxidizer. Once triggered, it becomes a chemical reaction that is
impressively exothermic, even if a lot of electrical energy is not
available.

The fixes are to severely under-rate the parts on voltage (1/2 to 1/3
rated voltage are suggested) and soft-start supplies to avoid high
peak currents.

Interestingly, most tant suppliers say to *never* use their parts
above 80% of "rated voltage."

In use, solid tantalums seem to have a declining failure rate versus
time, whereas aluminums, both electrolytic and polymer, eventually
fail... one from losing water, the other from gaining water!


John

John Larkin wrote:

On Fri, 27 Jul 2007 16:03:35 -0400, "Tom Del Rosso"
wrote:


"John Larkin" wrote in
message

It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there must be
some parameter that's being pushed. Voltage not derated enough?


High currents (ie, high dV/dT) causes tiny little sintered projections
to heat up. Tantalum metal is fuel and the MnO2 electrode is the
oxidizer. Once triggered, it becomes a chemical reaction that is
impressively exothermic, even if a lot of electrical energy is not
available.

The fixes are to severely under-rate the parts on voltage (1/2 to 1/3
rated voltage are suggested) and soft-start supplies to avoid high
peak currents.

Interestingly, most tant suppliers say to *never* use their parts
above 80% of "rated voltage."


I find that a rather dishonest specsmanship. "Here is our product and
here are the specs but please never use it up to those specs". Why don't
they just say 100uF/28V instead of 100uF/35V? All the more reason for me
not to use any tants.


In use, solid tantalums seem to have a declining failure rate versus
time, whereas aluminums, both electrolytic and polymer, eventually
fail... one from losing water, the other from gaining water!


Electrolytics often get too bad of a rap. I've got dozens and dozens
here that are about my age or older. Like the Hammond organ from 1961
where they put the cap right next to (!) the big rectifier tube. First
cap, still fine. Same for the ones in the Sachsenwerk radio from the
early 50's and the Astor BPJ radio here in the office which is also from
the 50's. Then there is the Rohde&Schwarz SMF generator which often ran
all day long. No fan, totally shielded, gets quite toasty in there. Has
the original electrolytics from around 1955, only the steel tube for the
oscillator is developing arthritis. But after over 50 years of dutiful
service that's ok.

--
Regards, Joerg

http://www.analogconsultants.com

On Fri, 27 Jul 2007 21:50:33 GMT, Joerg
wrote:

John Larkin wrote:

On Fri, 27 Jul 2007 16:03:35 -0400, "Tom Del Rosso"
wrote:


"John Larkin" wrote in
message

It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there must be
some parameter that's being pushed. Voltage not derated enough?


High currents (ie, high dV/dT) causes tiny little sintered projections
to heat up. Tantalum metal is fuel and the MnO2 electrode is the
oxidizer. Once triggered, it becomes a chemical reaction that is
impressively exothermic, even if a lot of electrical energy is not
available.

The fixes are to severely under-rate the parts on voltage (1/2 to 1/3
rated voltage are suggested) and soft-start supplies to avoid high
peak currents.

Interestingly, most tant suppliers say to *never* use their parts
above 80% of "rated voltage."


I find that a rather dishonest specsmanship. "Here is our product and
here are the specs but please never use it up to those specs". Why don't
they just say 100uF/28V instead of 100uF/35V? All the more reason for me
not to use any tants.


In use, solid tantalums seem to have a declining failure rate versus
time, whereas aluminums, both electrolytic and polymer, eventually
fail... one from losing water, the other from gaining water!


Electrolytics often get too bad of a rap. I've got dozens and dozens
here that are about my age or older. Like the Hammond organ from 1961
where they put the cap right next to (!) the big rectifier tube. First
cap, still fine. Same for the ones in the Sachsenwerk radio from the
early 50's and the Astor BPJ radio here in the office which is also from
the 50's. Then there is the Rohde&Schwarz SMF generator which often ran
all day long. No fan, totally shielded, gets quite toasty in there. Has
the original electrolytics from around 1955, only the steel tube for the
oscillator is developing arthritis. But after over 50 years of dutiful
service that's ok.

It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.

John

John Larkin wrote:

On Fri, 27 Jul 2007 21:50:33 GMT, Joerg
wrote:


John Larkin wrote:


On Fri, 27 Jul 2007 16:03:35 -0400, "Tom Del Rosso"
wrote:



"John Larkin" wrote in
message


It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there must be
some parameter that's being pushed. Voltage not derated enough?


High currents (ie, high dV/dT) causes tiny little sintered projections
to heat up. Tantalum metal is fuel and the MnO2 electrode is the
oxidizer. Once triggered, it becomes a chemical reaction that is
impressively exothermic, even if a lot of electrical energy is not
available.

The fixes are to severely under-rate the parts on voltage (1/2 to 1/3
rated voltage are suggested) and soft-start supplies to avoid high
peak currents.

Interestingly, most tant suppliers say to *never* use their parts
above 80% of "rated voltage."


I find that a rather dishonest specsmanship. "Here is our product and
here are the specs but please never use it up to those specs". Why don't
they just say 100uF/28V instead of 100uF/35V? All the more reason for me
not to use any tants.



In use, solid tantalums seem to have a declining failure rate versus
time, whereas aluminums, both electrolytic and polymer, eventually
fail... one from losing water, the other from gaining water!


Electrolytics often get too bad of a rap. I've got dozens and dozens
here that are about my age or older. Like the Hammond organ from 1961
where they put the cap right next to (!) the big rectifier tube. First
cap, still fine. Same for the ones in the Sachsenwerk radio from the
early 50's and the Astor BPJ radio here in the office which is also from
the 50's. Then there is the Rohde&Schwarz SMF generator which often ran
all day long. No fan, totally shielded, gets quite toasty in there. Has
the original electrolytics from around 1955, only the steel tube for the
oscillator is developing arthritis. But after over 50 years of dutiful
service that's ok.


It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.

--
Regards, Joerg

http://www.analogconsultants.com

On Fri, 27 Jul 2007 23:31:27 GMT, Joerg
wrote:

John Larkin wrote:

[snip]

It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.

"Overlooked in automotive"? What amateurs are you talking about? All
my automotive stuff was designed around -40°C to +140°C.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

John Larkin wrote:

....

It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.

John


What about such series as FK from Panasonic? Their impedance is
specified as only 3 times higher at -40°C than at 20°C (at 120Hz).

-- Andy

Jim Thompson wrote:

On Fri, 27 Jul 2007 23:31:27 GMT, Joerg
wrote:


John Larkin wrote:


[snip]

It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.


"Overlooked in automotive"? What amateurs are you talking about? All
my automotive stuff was designed around -40°C to +140°C.


Well, yes, AFAIR you worked for Bosch. They make the good stuff. But my
wife once had an "all electronic" car in Germany and then one night they
had a hard freeze. -20C or so. The whole thing went into hibernation,
even the dashboard didn't work anymore. There was battery juice. She
called the shop, they sent out the truck and brought the car into their
"thawing warehouse". After forking over some Deutschmarks it worked again.

--
Regards, Joerg

http://www.analogconsultants.com

On Sat, 28 Jul 2007 16:28:47 GMT, Joerg
wrote:

Jim Thompson wrote:

On Fri, 27 Jul 2007 23:31:27 GMT, Joerg
wrote:


John Larkin wrote:


[snip]

It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.


"Overlooked in automotive"? What amateurs are you talking about? All
my automotive stuff was designed around -40°C to +140°C.


Well, yes, AFAIR you worked for Bosch. They make the good stuff. But my
wife once had an "all electronic" car in Germany and then one night they
had a hard freeze. -20C or so. The whole thing went into hibernation,
even the dashboard didn't work anymore. There was battery juice. She
called the shop, they sent out the truck and brought the car into their
"thawing warehouse". After forking over some Deutschmarks it worked again.

Even the US stuff was specified at -40°C to +140°C.

Mercedes products are hilariously noted around here for "melting"
dashboard electronics ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

On Sat, 28 Jul 2007 16:28:47 GMT, Joerg
wrote:


Jim Thompson wrote:


On Fri, 27 Jul 2007 23:31:27 GMT, Joerg
wrote:



John Larkin wrote:


[snip]


It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.


"Overlooked in automotive"? What amateurs are you talking about? All
my automotive stuff was designed around -40°C to +140°C.


Well, yes, AFAIR you worked for Bosch. They make the good stuff. But my
wife once had an "all electronic" car in Germany and then one night they
had a hard freeze. -20C or so. The whole thing went into hibernation,
even the dashboard didn't work anymore. There was battery juice. She
called the shop, they sent out the truck and brought the car into their
"thawing warehouse". After forking over some Deutschmarks it worked again.


Even the US stuff was specified at -40°C to +140°C.


Haven't checked US vehicles lately. However, "specified" and "actually
performing" are often not the same thing.


Mercedes products are hilariously noted around here for "melting"
dashboard electronics ;-)


Here they hold up pretty good. For me they are too electronic though, I
prefer vehicles that are simpler.

--
Regards, Joerg

http://www.analogconsultants.com

On Sat, 28 Jul 2007 20:50:21 GMT, Joerg
wrote:

Jim Thompson wrote:

On Sat, 28 Jul 2007 16:28:47 GMT, Joerg
wrote:


Jim Thompson wrote:


On Fri, 27 Jul 2007 23:31:27 GMT, Joerg
wrote:



John Larkin wrote:


[snip]


It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.


"Overlooked in automotive"? What amateurs are you talking about? All
my automotive stuff was designed around -40°C to +140°C.


Well, yes, AFAIR you worked for Bosch. They make the good stuff. But my
wife once had an "all electronic" car in Germany and then one night they
had a hard freeze. -20C or so. The whole thing went into hibernation,
even the dashboard didn't work anymore. There was battery juice. She
called the shop, they sent out the truck and brought the car into their
"thawing warehouse". After forking over some Deutschmarks it worked again.


Even the US stuff was specified at -40°C to +140°C.


Haven't checked US vehicles lately. However, "specified" and "actually
performing" are often not the same thing.

Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.



Mercedes products are hilariously noted around here for "melting"
dashboard electronics ;-)


Here they hold up pretty good. For me they are too electronic though, I
prefer vehicles that are simpler.

It doesn't really get hot where you are ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Tom Del Rosso wrote:
"John Larkin" wrote in
message
It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there must be
some parameter that's being pushed. Voltage not derated enough?



Tants have a problem with surge currents more than voltage, which is why
they are not usually suitable for the input to a supply, and are ok at
the output provided it's a fairly stable load and can be soft started.
The critical rating for me is the rms and peak current v. temp.

Cheers

PeteS

PeteS wrote:

Tom Del Rosso wrote:
"John Larkin" wrote in
message
It's like with Saabs: great cars to drive, between fires.

That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there
must be some parameter that's being pushed. Voltage not derated
enough?



Tants have a problem with surge currents more than voltage, which is
why they are not usually suitable for the input to a supply, and are
ok at the output provided it's a fairly stable load and can be soft
started. The critical rating for me is the rms and peak current v.
temp.

Cheers

PeteS

Guess I could look this up, but what makes tants more/less desirable
for which reasons?

- YD.
--

YD wrote:
PeteS wrote:

Tom Del Rosso wrote:
"John Larkin" wrote in
message
It's like with Saabs: great cars to drive, between fires.
That's just a Saab story.

I've heard of tantalums exploding if reversed, but otherwise there
must be some parameter that's being pushed. Voltage not derated
enough?


Tants have a problem with surge currents more than voltage, which is
why they are not usually suitable for the input to a supply, and are
ok at the output provided it's a fairly stable load and can be soft
started. The critical rating for me is the rms and peak current v.
temp.

Cheers

PeteS

Guess I could look this up, but what makes tants more/less desirable
for which reasons?

- YD.

Tants have a very high capacitance density which is always desirable in
constrained space. Note that MLCC devices can also have high density,
although not as high as tants. MLCCs come with their own pros and cons,
of course.

They have low (but not very low) esr which can be a desirable trait,
particularly with LDOs and some switch mode converters (which was the
issue at the start of this thread). That comes down to (simplistically)
providing an output zero to maintain the feedback phase margin. Some
manufacturers have started to get the clue and provide converters of
this type that are stable with ceramics (esr in the 10s of milliohms or
lower). I've done converters that are stable with ceramics only but it
takes a little more work (it's necessary to add extra pole/zero pairs,
basically which means more components). Typical LDOs (such as the ones
from National) require an output esr in the range of 0.5 - 10 ohms for
stability incidentally.

The wet tants don't have particularly good esr characteristics across
extended temperature so sometimes it's a good idea to put a ceramic in
series with a small resistor in parallel with the tant to maintain the
output esr for loop stability reasons. Note that the increase in esr
increases the surge susceptibility.

Tants are very susceptible to high surge currents (di/dt rate seems to
be as much an issue as absolute surge) and can fail spectacularly
(pyrotechnically, in fact).

That's my view of them - how it affects where I use them depends on what
I need to do, of course. Personally, I only use them if I have no other
choice.

Cheers

PeteS

Jim Thompson wrote:

On Sat, 28 Jul 2007 20:50:21 GMT, Joerg
wrote:


Jim Thompson wrote:


On Sat, 28 Jul 2007 16:28:47 GMT, Joerg
wrote:



Jim Thompson wrote:



On Fri, 27 Jul 2007 23:31:27 GMT, Joerg
wrote:




John Larkin wrote:


[snip]



It depends on the crimped seals, which is a matter of luck. My other
problem with alums is that I want my gear to work to at least -20C,
perferably -40, and elec esr's skyrocket below 0C, so my switchers
will go crazy or at least make huge amounts of ripple.


Yes, that's a problem, one that is often overlooked in automotive. For
hi-rel stuff with temperature extremes I try to limit myself to
ceramics. It's amazing that you can get 10uF for pennies nowadays.


"Overlooked in automotive"? What amateurs are you talking about? All
my automotive stuff was designed around -40°C to +140°C.


Well, yes, AFAIR you worked for Bosch. They make the good stuff. But my
wife once had an "all electronic" car in Germany and then one night they
had a hard freeze. -20C or so. The whole thing went into hibernation,
even the dashboard didn't work anymore. There was battery juice. She
called the shop, they sent out the truck and brought the car into their
"thawing warehouse". After forking over some Deutschmarks it worked again.


Even the US stuff was specified at -40°C to +140°C.


Haven't checked US vehicles lately. However, "specified" and "actually
performing" are often not the same thing.


Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.



Mercedes products are hilariously noted around here for "melting"
dashboard electronics ;-)


Here they hold up pretty good. For me they are too electronic though, I
prefer vehicles that are simpler.


It doesn't really get hot where you are ;-)


It doesn't often get above 110F but it does go well below freezing.

--
Regards, Joerg

http://www.analogconsultants.com

On Mon, 30 Jul 2007 17:11:45 GMT, Joerg
wrote:

Jim Thompson wrote:

[snip]

Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.

[snip]

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

On Mon, 30 Jul 2007 17:11:45 GMT, Joerg
wrote:


Jim Thompson wrote:


[snip]

Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.


[snip]

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.


Depends on what failed. For example, it's highly unlikely that a
motorist had a spare radiator in the trunk ;-)

--
Regards, Joerg

http://www.analogconsultants.com

On Mon, 30 Jul 2007 18:05:43 GMT, Joerg
wrote:

Jim Thompson wrote:

On Mon, 30 Jul 2007 17:11:45 GMT, Joerg
wrote:


Jim Thompson wrote:


[snip]

Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.


[snip]

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.


Depends on what failed. For example, it's highly unlikely that a
motorist had a spare radiator in the trunk ;-)

Chewing gum ?:-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

On Mon, 30 Jul 2007 18:05:43 GMT, Joerg
wrote:


Jim Thompson wrote:


On Mon, 30 Jul 2007 17:11:45 GMT, Joerg
wrote:



Jim Thompson wrote:


[snip]


Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.


[snip]

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.


Depends on what failed. For example, it's highly unlikely that a
motorist had a spare radiator in the trunk ;-)


Chewing gum ?:-)


That works for small leaks. However, in the old days some of the
mechanical parts in a car weren't as reliable as today so there
certainly is progress. For example, sometimes the thermostat failed and
by the time the driver noticed that the temp gauge had pegged white
plumes billowed from under the hood. I've seen cases where for some
reason the hoses held but the radiator simply split open.

Then there is that dreaded water pump where you typically don't have a
spare in the trunk either. There are brands that fail all the time and
then there are the Japanese cars where they seem to last forever. Once
when my Chrysler pump failed for the umpteenth time I'd had it and
adapted a Mercedes pump. Never failed again ....

--
Regards, Joerg

http://www.analogconsultants.com

On Mon, 30 Jul 2007 12:15:11 -0700, Joerg
wrote:

Jim Thompson wrote:

On Mon, 30 Jul 2007 18:05:43 GMT, Joerg
wrote:


Jim Thompson wrote:


On Mon, 30 Jul 2007 17:11:45 GMT, Joerg
wrote:



Jim Thompson wrote:


[snip]


Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.


[snip]

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.


Depends on what failed. For example, it's highly unlikely that a
motorist had a spare radiator in the trunk ;-)


Chewing gum ?:-)


That works for small leaks. However, in the old days some of the
mechanical parts in a car weren't as reliable as today so there
certainly is progress. For example, sometimes the thermostat failed and
by the time the driver noticed that the temp gauge had pegged white
plumes billowed from under the hood. I've seen cases where for some
reason the hoses held but the radiator simply split open.

Then there is that dreaded water pump where you typically don't have a
spare in the trunk either. There are brands that fail all the time and
then there are the Japanese cars where they seem to last forever. Once
when my Chrysler pump failed for the umpteenth time I'd had it and
adapted a Mercedes pump. Never failed again ....

You bought a Chrysler product ?:-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

On Mon, 30 Jul 2007 12:15:11 -0700, Joerg
wrote:


Jim Thompson wrote:


On Mon, 30 Jul 2007 18:05:43 GMT, Joerg
wrote:



Jim Thompson wrote:



On Mon, 30 Jul 2007 17:11:45 GMT, Joerg
wrote:




Jim Thompson wrote:


[snip]



Well! In the golden days when I designed car parts we TESTED -40°C to
+160°C.


Yeah, those golden days. Problem is, some of the gold seems to have
flaked off in the automotive area.

In the golden days cars often let you down when they overheated but that
usually just required patience and maybe a water source nearby. Nowadays
a dashboard light comes on and it's all over. It's not that I am against
electronics in cars but I'd prefer it more in moderation.


[snip]

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.


Depends on what failed. For example, it's highly unlikely that a
motorist had a spare radiator in the trunk ;-)


Chewing gum ?:-)


That works for small leaks. However, in the old days some of the
mechanical parts in a car weren't as reliable as today so there
certainly is progress. For example, sometimes the thermostat failed and
by the time the driver noticed that the temp gauge had pegged white
plumes billowed from under the hood. I've seen cases where for some
reason the hoses held but the radiator simply split open.

Then there is that dreaded water pump where you typically don't have a
spare in the trunk either. There are brands that fail all the time and
then there are the Japanese cars where they seem to last forever. Once
when my Chrysler pump failed for the umpteenth time I'd had it and
adapted a Mercedes pump. Never failed again ....


You bought a Chrysler product ?:-)


Well, that was right after getting my engineering degree. IOW when the
budget was starting at the "pre-employment level". My old Citroen 2CV
could not pass another road safety check at 16 years and those are
mandatory in Germany. Plus a car that tops out around 50mph and needs to
be started with a crank ain't so hot when you have to pick up clients
from the airport ;-)

So I bought a Horizon. A very practical car, just not of the highest
quality. Then I gave it to my brother. Some time later while he was
driving it he felt it wanting to take off like an airplane. A peek into
the rearview 'splained it: The whole right rear suspension had entered
the passenger compartment. Then I bought a big Audi Station. Best car I
ever had but the Mits I've got now is also really good, just eats a lot
more gas.

--
Regards, Joerg

http://www.analogconsultants.com

Jim Thompson wrote:


I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.

...Jim Thompson

I'm not aware of any new cars that have only a single uP. Everything since
the OBD and CAN systems has a microprocessor where it is needed, and a bus
that runs through the car to the various microprocessors. Many new cars have
a microprocessor for the engine, one for the transmission, one for the air
bag systems, one for the brakes, one for climate control, one for the
stereo/CD/MP3 player, one for the navigation system, one for the autodarkening
rear view mirror/compass, one for the dash board, one for the HVAC....

Your Datsun probably has one for the arm rests, and tail lights too ;-)

-Chuck

On Mon, 30 Jul 2007 16:25:19 -0400, Chuck Harris
wrote:

Jim Thompson wrote:


I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.

...Jim Thompson

I'm not aware of any new cars that have only a single uP. Everything since
the OBD and CAN systems has a microprocessor where it is needed, and a bus
that runs through the car to the various microprocessors. Many new cars have
a microprocessor for the engine, one for the transmission, one for the air
bag systems, one for the brakes, one for climate control, one for the
stereo/CD/MP3 player, one for the navigation system, one for the autodarkening
rear view mirror/compass, one for the dash board, one for the HVAC....

Your Datsun probably has one for the arm rests, and tail lights too ;-)

-Chuck

Q45, GPS/Navigation, Sirius/FM/AM, CD, tape, seats (front and back),
HVAC controls (front and back), back-up camera, electric windows,
heated/cooled seats, 8 air bags, cruise control, adjustable suspension
and rear-end, sun roof, 0-60 mph acceleration time of 6.7 seconds, and
340 hp (253 kW) 4.5 L VK45DE V8 engine, and 333 lb-ft of torque

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

"Jim Thompson" wrote in
message ...

I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.

Sad isn't it?

I found out in Albuquerque when the battery developed an open
cell. The dash lights all lit, getting brighter and dimmer with
the rpm. Then I discovered the transmission was electronically
shifted. I barely got it out of traffic.

That's why I like my standard even though they can have problems
too.

Chuck Harris wrote:

Jim Thompson wrote:


I'd prefer as it was in my day... multiple systems, so one failure
doesn't stop you completely, as these single uP designs do.

...Jim Thompson


I'm not aware of any new cars that have only a single uP. Everything since
the OBD and CAN systems has a microprocessor where it is needed, and a bus
that runs through the car to the various microprocessors. Many new cars
have
a microprocessor for the engine, one for the transmission, one for the air
bag systems, one for the brakes, one for climate control, one for the
stereo/CD/MP3 player, one for the navigation system, one for the
autodarkening
rear view mirror/compass, one for the dash board, one for the HVAC....

Your Datsun probably has one for the arm rests, and tail lights too ;-)


AFAIK my Mitsubishi Montero Sport has only one, for the engine control
unit. That's enough uC in a car for me.

--
Regards, Joerg

http://www.analogconsultants.com