dc/dc converter 12/200V

John Larkin · Apr 18, 2005

On Mon, 18 Apr 2005 14:11:14 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Mon, 18 Apr 2005 13:05:43 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Mon, 18 Apr 2005 09:34:53 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Mon, 18 Apr 2005 09:02:17 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Mon, 18 Apr 2005 17:49:52 +0200, "Frithiof Andreas Jensen"
frithiof.jensen@die_spammer_die.ericsson.com> wrote:

"Jim Thompson" <thegreatone@example.com> wrote in message
news:bme261lenefta1ne07j5nahl8vuqbr7cco@4ax.com...
Why do it in to steps, conversion, then firing circuitry.

Do it in one pass, see....

http://www.analog-innovations.com/SED/CD-Ignition-Basic.pdf

Arrr - how annoyingly simple and obvious after the fact - Smarty-Pants Git,
You ;-)

That's a *very neat* & *elegant* idea - in case you missed the smiley -
Cheap too!

That is very elegant. But is there an advantage to having an
energy-storage inductor, an energy-storage capacitor, and a coil, when
all three can be combined into one part, namely the coil?

John

As Frithiof say, "CHEAP".

Power dissipation is much lower... device is always saturated.

Only if you time the base drive right. Your circuit really needs "on"
timing adjustment as a function of battery voltage, or alternately a
current sensor.

Simple control requirements allow use of star-wheel-magnetic pickup OR
points.

Inductive storage requires either a shaped pickup or complex control
system for low dissipation and avoidance of coil current all over the
map.

That's easy. Your circuit needs base timing, too. 50 cents worth of uP
looks like a pretty good deal to eliminate a big inductor and a big
cap.

Remember, charging an inductor takes a fixed TIME, NOT a fixed
number of degrees.

I'm so grateful I have revered elders around to teach me the
fundamentals.

John

Don't be a smart-ass, John. Modern inductive storage ignitions DO
just that... BUT... it requires a pickup on the flywheel so you know
where you are.

...Jim Thompson

Why? It's a simple timing thing to turn on the coil drive some
reasonable number of milliseconds before the "points" give you the
firing signal. After all, just the firing signals tell you the rpm's,
and everything follows from that. Might as well do the advance in
software while you're at it. Going constant-current certainly helps
during cranking and such, but that's a refinement.

John

Jim Thompson · Apr 18, 2005

On Mon, 18 Apr 2005 14:28:49 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

Why? It's a simple timing thing to turn on the coil drive some
reasonable number of milliseconds before the "points" give you the
firing signal. After all, just the firing signals tell you the rpm's,
and everything follows from that. Might as well do the advance in
software while you're at it. Going constant-current certainly helps
during cranking and such, but that's a refinement.

John

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Apr 18, 2005

On Mon, 18 Apr 2005 14:28:49 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

Why? It's a simple timing thing to turn on the coil drive some
reasonable number of milliseconds before the "points" give you the
firing signal. After all, just the firing signals tell you the rpm's,
and everything follows from that. Might as well do the advance in
software while you're at it. Going constant-current certainly helps
during cranking and such, but that's a refinement.

John

480)460-2350 | |
| E-mail Address at Website Fax

Mike Monett · Apr 18, 2005

John Larkin wrote:

[...]

Power dissipation is much lower... device is always saturated.

Only if you time the base drive right. Your circuit really needs "on"
timing adjustment as a function of battery voltage, or alternately a
current sensor.

Jim's circuit really is very elegant, John. Do it in SPICE - then you see
how well he has done.

You don't need a current sensor or fancy drive electronics. Just make the
base current sufficient to make a spark at worst-case ambient temp,
battery voltage, and include a fudge factor for old ladies who never got
around to switching their summer weight 40W100 oil.

Simple control requirements allow use of star-wheel-magnetic pickup OR
points.

Inductive storage requires either a shaped pickup or complex control
system for low dissipation and avoidance of coil current all over the
map.

That's easy. Your circuit needs base timing, too. 50 cents worth of uP
looks like a pretty good deal to eliminate a big inductor and a big
cap.

Then how do you get a spark? Where is the energy storage?

In Jim's circuit, all you need is a fixed width base drive to saturate
the tranny.

His circuit wastes the first trigger pulse. After that, 400V is sitting
on the collector waiting for the leading edge of a trigger to dump the
charge into the ignition coil.

I love circuits like that! Brilliant. Elegant. Even I can understand how
they work. Bulletproof. Minimum parts count. Pennies for the components.

Why do it any other way?

Remember, charging an inductor takes a fixed TIME, NOT a fixed
number of degrees.

[... snip]

John

Mike Monett

Jim Thompson · Apr 18, 2005

On Mon, 18 Apr 2005 19:45:20 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[...]

Power dissipation is much lower... device is always saturated.

Only if you time the base drive right. Your circuit really needs "on"
timing adjustment as a function of battery voltage, or alternately a
current sensor.

Jim's circuit really is very elegant, John. Do it in SPICE - then you see
how well he has done.

You don't need a current sensor or fancy drive electronics. Just make the
base current sufficient to make a spark at worst-case ambient temp,
battery voltage, and include a fudge factor for old ladies who never got
around to switching their summer weight 40W100 oil.

Simple control requirements allow use of star-wheel-magnetic pickup OR
points.

Inductive storage requires either a shaped pickup or complex control
system for low dissipation and avoidance of coil current all over the
map.

That's easy. Your circuit needs base timing, too. 50 cents worth of uP
looks like a pretty good deal to eliminate a big inductor and a big
cap.

Then how do you get a spark? Where is the energy storage?

In Jim's circuit, all you need is a fixed width base drive to saturate
the tranny.

His circuit wastes the first trigger pulse. After that, 400V is sitting
on the collector waiting for the leading edge of a trigger to dump the
charge into the ignition coil.

I love circuits like that! Brilliant. Elegant. Even I can understand how
they work. Bulletproof. Minimum parts count. Pennies for the components.

Why do it any other way?

Remember, charging an inductor takes a fixed TIME, NOT a fixed
number of degrees.

[... snip]

John

Mike Monett

480)460-2350 | |
| E-mail Address at Website Fax

John Larkin · Apr 18, 2005

On Mon, 18 Apr 2005 19:45:20 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[...]

Power dissipation is much lower... device is always saturated.

Only if you time the base drive right. Your circuit really needs "on"
timing adjustment as a function of battery voltage, or alternately a
current sensor.

Jim's circuit really is very elegant, John. Do it in SPICE - then you see
how well he has done.

I hardly need Spice to understand how a thing like this works.

You don't need a current sensor or fancy drive electronics. Just make the
base current sufficient to make a spark at worst-case ambient temp,
battery voltage, and include a fudge factor for old ladies who never got
around to switching their summer weight 40W100 oil.

The inductor current builds as something like Vb/Ton, and the spark
energy goes as I^2. So low battery voltage, as in cold cranking, would
seem to need a longer (not higher current) base drive. Spice that!

Simple control requirements allow use of star-wheel-magnetic pickup OR
points.

Inductive storage requires either a shaped pickup or complex control
system for low dissipation and avoidance of coil current all over the
map.

That's easy. Your circuit needs base timing, too. 50 cents worth of uP
looks like a pretty good deal to eliminate a big inductor and a big
cap.

Then how do you get a spark? Where is the energy storage?

Store it in the coil, like people have been doing for a century now.

In Jim's circuit, all you need is a fixed width base drive to saturate
the tranny.

Not if you want to get to work every morning.

His circuit wastes the first trigger pulse. After that, 400V is sitting
on the collector waiting for the leading edge of a trigger to dump the
charge into the ignition coil.

Actually, it's tricky to get high stepup ratios in circuits like this.
As the boost ratio increases, energy gets lost in the various
parasitics. You're suggesting a 100:1 boost (4v cold cranking, 400v
peak out) and that's pushing things.

I love circuits like that! Brilliant. Elegant. Even I can understand how
they work. Bulletproof. Minimum parts count. Pennies for the components.

Why do it any other way?

To save a lot of size and money; neither the L nor the C will cost
pennies. Does any carmaker actually do it this way?

John

Jim Thompson · Apr 19, 2005

On Tue, 19 Apr 2005 07:29:02 -0500, "Aubrey McIntosh, Ph.D."
<newsposter@spam.vima.austin.tx.us> wrote:

Jim Thompson wrote:

Wrong. My example is NOT inductive "storage"... it's CONVERT PER
FIRING... the example shown can manage a firing every 2.25ms with the
battery at 12VDC. AND: It HAS been run on many high RPM V8's, for
YEARS... not a FIGMENT like lots of designs seen here on S.E.D ;-)

...Jim Thompson

What is a typical inductance for an ignition coil?

I don't really remember for sure now. For inductive storage driven by
a transistor, they're ~5mH. I believe off-the-shelf coils are about
the same inductance.

My "CD", using 5mH for "charging" and an off-the-shelf coil, will blow
a droplet of oil out of a spark-plug gap, and will burn a hole
straight through 1/8" plexiglass.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Mike Monett · Apr 19, 2005

John Larkin wrote:

[...]

The inductor current builds as something like Vb/Ton, and the
spark energy goes as I^2. So low battery voltage, as in cold
cranking, would seem to need a longer (not higher current) base
drive. Spice that!

Easy - increase the pulse width while cranking. Actually, SPICE
shows it very well!

[...]

His circuit wastes the first trigger pulse. After that, 400V is
sitting on the collector waiting for the leading edge of a
trigger to dump the charge into the ignition coil.

Actually, it's tricky to get high stepup ratios in circuits like
this. As the boost ratio increases, energy gets lost in the
various parasitics. You're suggesting a 100:1 boost (4v cold
cranking, 400v peak out) and that's pushing things.

4V while cranking? I think battery specs are a bit higher. And
regular ignition systems would also run into problems.

Anyway, there's lots of time to charge the coil while cranking. Jim
apparently had no problems. Of course, Arizona winter is mild
compared to Canada

I love circuits like that! Brilliant. Elegant. Even I can
understand how they work. Bulletproof. Minimum parts count.
Pennies for the components.

Why do it any other way?

To save a lot of size and money; neither the L nor the C will cost
pennies. Does any carmaker actually do it this way?

Jim said the coil cost a buck. Fairchild has inexpensive IGBT
transistors for auto ignitions for less than a buck. The cap may
cost a buck. Three dollars and change.

The regular Kettering ignition also needs a coil and transistor, so
the price increment may be only one dollar for the cap.

Jim's design is ideal for older cars with a weak ignition, which is
the market for CD ignition systems. These may cost perhaps $50 for a
cheap one to $500 for a high end. Here's one for $120:

http://www.partshopper.com/fordmustang/Items/MAL-650-6852M.html

Jim's design would also be useful in triggers for high power
strobes, boat engines, maybe even in auto engines used for aircraft
where spark energy, weight and reliability are crucial. Providing
the energy needed for ignition with a single inductor, a cap and
three diodes is a tremendous improvement over the weight and
complexity of conventional cd ignition.

Carmakers seem to be moving to coil-on-plug which have individual
ignition coils for each plug or pair of plugs. This eliminates the
high voltage harness, and provides greater charging time for the
coil which increases the spark energy:

http://hostingprod.com/@aa1car.com/library/copign.htm

John

Mike Monett

Jim Thompson · Apr 19, 2005

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[snip]

Actually, it's tricky to get high stepup ratios in circuits like
this. As the boost ratio increases, energy gets lost in the
various parasitics. You're suggesting a 100:1 boost (4v cold
cranking, 400v peak out) and that's pushing things.

John is confused ;-) 0.5*L*I^2 = 0.5*C*V^2

INDUCTIVE charging, so John's ratio is meaningless

4V while cranking?

4V Cranking is for real... COLD

I think battery specs are a bit higher. And
regular ignition systems would also run into problems.

Operating temperature range -40°C to +140°C

Anyway, there's lots of time to charge the coil while cranking. Jim
apparently had no problems. Of course, Arizona winter is mild
compared to Canada

Actually, in the winter time, Arizona will have the record high AND
LOW temperatures for the day. Out desert regions, like Phoenix, will
have the high temperature, and a place called Hawley Lake up in the
White Mountains will be at -40°F at the same time ;-)

[snip]

Mike Monett

480)460-2350 | |
| E-mail Address at Website Fax

John Larkin · Apr 19, 2005

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[...]

The inductor current builds as something like Vb/Ton, and the
spark energy goes as I^2. So low battery voltage, as in cold
cranking, would seem to need a longer (not higher current) base
drive. Spice that!

Easy - increase the pulse width while cranking. Actually, SPICE
shows it very well!

Oh. I thought somebody was saying something like

"all you need is a fixed width base drive to saturate
the tranny."

Can't remember who.

His circuit wastes the first trigger pulse. After that, 400V is
sitting on the collector waiting for the leading edge of a
trigger to dump the charge into the ignition coil.

Actually, it's tricky to get high stepup ratios in circuits like
this. As the boost ratio increases, energy gets lost in the
various parasitics. You're suggesting a 100:1 boost (4v cold
cranking, 400v peak out) and that's pushing things.

4V while cranking? I think battery specs are a bit higher. And
regular ignition systems would also run into problems.

Someone else here cited the 4V. Sounds reasonable to me. I hate to
hike in the snow.

Anyway, there's lots of time to charge the coil while cranking. Jim
apparently had no problems. Of course, Arizona winter is mild
compared to Canada

I love circuits like that! Brilliant. Elegant. Even I can
understand how they work. Bulletproof. Minimum parts count.
Pennies for the components.

Why do it any other way?

To save a lot of size and money; neither the L nor the C will cost
pennies. Does any carmaker actually do it this way?

Jim said the coil cost a buck. Fairchild has inexpensive IGBT
transistors for auto ignitions for less than a buck. The cap may
cost a buck. Three dollars and change.

The regular Kettering ignition also needs a coil and transistor, so
the price increment may be only one dollar for the cap.

Sooms to me that two inductive components are not the same thing as
one inductive component. Do you disagree?

Jim's design is ideal for older cars with a weak ignition, which is
the market for CD ignition systems. These may cost perhaps $50 for a
cheap one to $500 for a high end. Here's one for $120:

http://www.partshopper.com/fordmustang/Items/MAL-650-6852M.html

Jim's design

I think Jim said it wasn't his design.

would also be useful in triggers for high power
strobes, boat engines, maybe even in auto engines used for aircraft
where spark energy, weight and reliability are crucial. Providing
the energy needed for ignition with a single inductor, a cap and
three diodes is a tremendous improvement over the weight and
complexity of conventional cd ignition.

Complexity, barely; weight and cost, absolutely not. This is a big
inductor, because it has to store *all* the shot energy all at once.

If I wanted to go CD - and I'm not sure why I would - it seems more
sensible to use an oscillating flyback converter with a small ferrite
step-up transformer and voltage feedback to charge the cap. Silicon is
practically free, but the 5 mH inductor will be a beast.

This is a wonderful, fun, clever circuit. It's just not very
practical. Things like that are often hard to let go of, but if it's
not a good engineering choice, it must be let go of.

John

Mike Monett · Apr 19, 2005

Mike Monett wrote:

[...]

Jim said the coil cost a buck. Fairchild has inexpensive IGBT
transistors for auto ignitions for less than a buck. The cap may
cost a buck. Three dollars and change.

I can't count. It still needs an ignition coil.

The regular Kettering ignition also needs a coil and transistor, so
the price increment may be only one dollar for the cap.

Plus $1 for the inductor. Two bucks plus change for the diodes.

About the cost of one gallon of gas

Mike Monett

Mike Monett · Apr 19, 2005

Jim Thompson wrote:

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

[...]

4V while cranking?

4V Cranking is for real... COLD

Golly, no wonder my car clock loses time on a real cold winter morning

So the voltage drop of the extra diode in series with the collector
becomes more significant?

I think battery specs are a bit higher. And
regular ignition systems would also run into problems.

Operating temperature range -40°C to +140°C

Automotive has tough specs.

Anyway, there's lots of time to charge the coil while cranking. Jim
apparently had no problems. Of course, Arizona winter is mild
compared to Canada

Actually, in the winter time, Arizona will have the record high AND
LOW temperatures for the day. Out desert regions, like Phoenix, will
have the high temperature, and a place called Hawley Lake up in the
White Mountains will be at -40°F at the same time ;-)

I flew from St. Paul, Minn. to Phoenix one winter. St. Paul was something
like -30F, Phoenix was something like +120F. I still remember the heat
shock

...Jim Thompson

Mike Monett

Jim Thompson · Apr 19, 2005

On Tue, 19 Apr 2005 12:08:48 -0400, Mike Monett <no@spam.com> wrote:

Jim Thompson wrote:

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

[...]

4V while cranking?

4V Cranking is for real... COLD

Golly, no wonder my car clock loses time on a real cold winter morning

So the voltage drop of the extra diode in series with the collector
becomes more significant?

Even if you figure only 2.5V available for the inductor during crank,
you get to 5A in 10ms, quite adequate for starting. At (600RPM) idle
a V8 has 25ms between firings.

I think battery specs are a bit higher. And
regular ignition systems would also run into problems.

Operating temperature range -40°C to +140°C

Automotive has tough specs.

Anyway, there's lots of time to charge the coil while cranking. Jim
apparently had no problems. Of course, Arizona winter is mild
compared to Canada

Actually, in the winter time, Arizona will have the record high AND
LOW temperatures for the day. Out desert regions, like Phoenix, will
have the high temperature, and a place called Hawley Lake up in the
White Mountains will be at -40°F at the same time ;-)

I flew from St. Paul, Minn. to Phoenix one winter. St. Paul was something
like -30F, Phoenix was something like +120F. I still remember the heat
shock

...Jim Thompson

Mike Monett

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Apr 19, 2005

On Tue, 19 Apr 2005 09:04:44 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[snip]

Jim's design

I think Jim said it wasn't his design.

Not my CONCEPT. But I, as they say, "reduced it to practice".

[snip]

This is a wonderful, fun, clever circuit. It's just not very
practical. Things like that are often hard to let go of, but if it's
not a good engineering choice, it must be let go of.

John

Get over it, John. It IS very practical for someone spinning their
own.

It made it into Ford's racing cars, but not into production
vehicles... not because of cost or size, but due to Ford's concern
that poorly maintained vehicles would start misfiring due to the short
spark duration.

They were wrong about that. (Some of the managers I had to deal with
were engineers who had worked for Ford since Henry the First

480)460-2350 | |
| E-mail Address at Website Fax

John Larkin · Apr 19, 2005

On Tue, 19 Apr 2005 08:53:01 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[snip]

Actually, it's tricky to get high stepup ratios in circuits like
this. As the boost ratio increases, energy gets lost in the
various parasitics. You're suggesting a 100:1 boost (4v cold
cranking, 400v peak out) and that's pushing things.

John is confused ;-) 0.5*L*I^2 = 0.5*C*V^2

Good thing you smilied that one. I'd have to be seriously drunk to get
confused over anything this simple.

INDUCTIVE charging, so John's ratio is meaningless

Boost step-up ratios are not meaningless. High ratios get expensive,
which is why people tend to prefer transformers for high Vout/Vin
ratios on dc/dc converters.

This circuit is cute and clever, and one could certainly build one and
get it to work (provided the base drive timing assured full energy
transfer at min cranking voltage and didn't fry things at max), but I
don't think it's the way people would do this in production.

Its very cleverness is the danger here.

John

Jim Thompson · Apr 19, 2005

On Tue, 19 Apr 2005 10:16:04 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Tue, 19 Apr 2005 08:53:01 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[snip]

Actually, it's tricky to get high stepup ratios in circuits like
this. As the boost ratio increases, energy gets lost in the
various parasitics. You're suggesting a 100:1 boost (4v cold
cranking, 400v peak out) and that's pushing things.

John is confused ;-) 0.5*L*I^2 = 0.5*C*V^2

Good thing you smilied that one. I'd have to be seriously drunk to get
confused over anything this simple.

INDUCTIVE charging, so John's ratio is meaningless

Boost step-up ratios are not meaningless. High ratios get expensive,
which is why people tend to prefer transformers for high Vout/Vin
ratios on dc/dc converters.

This circuit is cute and clever, and one could certainly build one and
get it to work (provided the base drive timing assured full energy
transfer at min cranking voltage and didn't fry things at max), but I
don't think it's the way people would do this in production.

Its very cleverness is the danger here.

John

I can't believe you are so confused, John. You are TOTALLY
out-to-lunch on this one.

From a previous post...

"Turning ON the transistor does two things... dumps the capacitor
through the ignition coil primary (firing the plug) and begins
charging L1.

When the L1 current reaches 5A a control circuit (not shown) turns off
the transistor, which dumps the L1 energy into the capacitor.

Next point opening, or star wheel control signal, turns on the
transistor, repeating the cycle."

Did you miss the part where a "control circuit" turns the device off
when 5A is attained? The current is MEASURED!

The device WAS made in production quantities. What is it you think
made it not mass-producible?

(Maybe you missing the point that the control circuit is not shown,
but it's an integrated circuit with bandgap, smarts, etc. I think
you're also missing the point that the capacitor gets discharged
completely each firing cycle.)

Other folk had no trouble understanding it ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

John Larkin · Apr 19, 2005

On Tue, 19 Apr 2005 11:04:06 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Tue, 19 Apr 2005 10:16:04 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Tue, 19 Apr 2005 08:53:01 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Tue, 19 Apr 2005 11:19:27 -0400, Mike Monett <no@spam.com> wrote:

John Larkin wrote:

[snip]

Actually, it's tricky to get high stepup ratios in circuits like
this. As the boost ratio increases, energy gets lost in the
various parasitics. You're suggesting a 100:1 boost (4v cold
cranking, 400v peak out) and that's pushing things.

John is confused ;-) 0.5*L*I^2 = 0.5*C*V^2

Good thing you smilied that one. I'd have to be seriously drunk to get
confused over anything this simple.

INDUCTIVE charging, so John's ratio is meaningless

Boost step-up ratios are not meaningless. High ratios get expensive,
which is why people tend to prefer transformers for high Vout/Vin
ratios on dc/dc converters.

This circuit is cute and clever, and one could certainly build one and
get it to work (provided the base drive timing assured full energy
transfer at min cranking voltage and didn't fry things at max), but I
don't think it's the way people would do this in production.

Its very cleverness is the danger here.

John

I can't believe you are so confused, John. You are TOTALLY
out-to-lunch on this one.

From a previous post...

"Turning ON the transistor does two things... dumps the capacitor
through the ignition coil primary (firing the plug) and begins
charging L1.

When the L1 current reaches 5A a control circuit (not shown) turns off
the transistor, which dumps the L1 energy into the capacitor.

Next point opening, or star wheel control signal, turns on the
transistor, repeating the cycle."

Did you miss the part where a "control circuit" turns the device off
when 5A is attained? The current is MEASURED!

The device WAS made in production quantities. What is it you think
made it not mass-producible?

(Maybe you missing the point that the control circuit is not shown,
but it's an integrated circuit with bandgap, smarts, etc. I think
you're also missing the point that the capacitor gets discharged
completely each firing cycle.)

Other folk had no trouble understanding it ;-)

...Jim Thompson

Gosh, Jim, you're getting crabby. Of course I understand it; I did
point out, somewhere way up above, that the base drive width had to be
adaptive, perhaps with current sensing, to keep the energy per zap
constant.

Your insistance that I don't understand how it works is surprising.

John

Jim Thompson · Apr 19, 2005

On Tue, 19 Apr 2005 12:16:57 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

Gosh, Jim, you're getting crabby. Of course I understand it; I did
point out, somewhere way up above, that the base drive width had to be
adaptive, perhaps with current sensing, to keep the energy per zap
constant.

Your insistance that I don't understand how it works is surprising.

John

480)460-2350 | |
| E-mail Address at Website Fax

Rich Grise · Apr 19, 2005

On Tue, 19 Apr 2005 09:38:48 -0700, Jim Thompson wrote:

On Tue, 19 Apr 2005 12:08:48 -0400, Mike Monett <no@spam.com> wrote:
Jim Thompson wrote:
....
Actually, in the winter time, Arizona will have the record high AND
LOW temperatures for the day. Out desert regions, like Phoenix, will
have the high temperature, and a place called Hawley Lake up in the
White Mountains will be at -40°F at the same time ;-)

I flew from St. Paul, Minn. to Phoenix one winter. St. Paul was something
like -30F, Phoenix was something like +120F. I still remember the heat
shock

You doth exaggerate, it hasn't been over 92°F this month ;-)

I've only seen > 120°F here two days out of the 43 years I've lived
here.

But when you get on an airplane in the morning and it's -30F out, and step

off into, say, 85, 90F in the afternoon, it _feels_ like 120!

Of course, I can one-up Mike. Flew from MSP/snow to Khorat, Thailand,
where it really _is_ 120! But people get used to the heat: about the
second day there I was miserable - they gave me some Kaopectate and
told me to drink a lot of water - and the next day I was fine, although
I've never been able to tolerate cold since. In Thailand, in the dead of
winter when it gets down to 65, people freeze to death.

Cheers!
Rich

John Larkin · Apr 19, 2005

On Tue, 19 Apr 2005 13:40:37 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Tue, 19 Apr 2005 12:16:57 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

Gosh, Jim, you're getting crabby. Of course I understand it; I did
point out, somewhere way up above, that the base drive width had to be
adaptive, perhaps with current sensing, to keep the energy per zap
constant.

Your insistance that I don't understand how it works is surprising.

John

Me? Crabby? I thought maybe you had one too many Hefe Weizen ;-)

No. My spicy stir-fry chicken demands one of those big Kirins.

Way back I DID explain the control system had "smarts".

And you kept insisting it wasn't "production".

Well, I did ask. Are race cars "production"?

John

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