I saw a web page somewhere that had a circuit you could build to
replace the points and condenser on a lawnmower engine, but I lost it.
Can someone point me to it?
Thanks,


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

Ron Thompson wrote in article
...
I saw a web page somewhere that had a circuit you could build to
replace the points and condenser on a lawnmower engine, but I lost it.
Can someone point me to it?
Thanks,


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)



When I managed a NAPA store, we sold an inexpensive (under $20) electronic
ignition conversion for B&S among others.

Bob Paulin - R.A.C.E.
Race Car Chassis Analysis & Setup Services

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David




"Ron Thompson" wrote in message
news
I saw a web page somewhere that had a circuit you could build to
replace the points and condenser on a lawnmower engine, but I lost it.
Can someone point me to it?
Thanks,


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David
Thanks, that's the idea. But I was looking for the home built circuit.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

On Tue, 08 Jun 2004 21:16:01 GMT, Ron Thompson
wrote:

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David
Thanks, that's the idea. But I was looking for the home built circuit.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Try www.modelflight.com/ignition.html
All I did was google for "electronic ignition circuit" This one is
battery operated. All the home made ones I seen use a battery.
ERS

On Tue, 08 Jun 2004 21:16:01 GMT, Ron Thompson
wrote:

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David
Thanks, that's the idea. But I was looking for the home built circuit.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Try www.modelflight.com/ignition.html
All I did was google for "electronic ignition circuit" This one is
battery operated. All the home made ones I seen use a battery.
ERS
Yeah, me too. Not much good on a lawnmower.
I thought I had the other one saved on my computer, but I can't find
it.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

I don't think that those "electronic ignitions" for lawnmower engines are
anything more than a hefty zener diode. I'm sure that there must be a
small-engine group (or 10) somewhere on the Internet where you could get a more
definitive answer. In my fuzzy experience, you just bolt "the part" to a
grounded part of the engine and hook it's one wire to the points connection. It
works fine, and resultantly I doubt if they have been putting mechanical points
in lawnmowers for the last 15 or 20 years.

I run a communications shop and we have drawers full of parts, some of
which would likely do the job just fine. That said; if I needed that part, I
would go to somewhere where they sell lawnmower parts and buy one. My time has
a certain small amount of value to me.

Vaughn


"Ron Thompson" wrote in message
news
I saw a web page somewhere that had a circuit you could build to
replace the points and condenser on a lawnmower engine, but I lost it.
Can someone point me to it?
Thanks,


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center,
USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

On Tue, 08 Jun 2004 22:30:32 GMT, Ron Thompson
wrote:

On Tue, 08 Jun 2004 21:16:01 GMT, Ron Thompson
wrote:

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David
Thanks, that's the idea. But I was looking for the home built circuit.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Try www.modelflight.com/ignition.html
All I did was google for "electronic ignition circuit" This one is
battery operated. All the home made ones I seen use a battery.
ERS
Yeah, me too. Not much good on a lawnmower.
I thought I had the other one saved on my computer, but I can't find
it.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Ron- I have used the ones you can buy for about 10 bucks. Some in
plastic cases and others in metal cases. They all worked perfectly.
Interestingly, B&S used some kind of coil in their electronic ignition
to sense the magnet on the flywheel. And these ignitions were not that
reliable. The ones you buy must sense the voltage build up and fire
then. In a magneto ignition system the magnet needs to be passing the
coil when the points open to get a good spark. I don't know how the
retrofit systems know exactly when to fire. Different magnetos will
have different voltages. The first ones I saw had to be bought for the
right engine but the last one I bought said it would work on any
engine. And it worked on a B&S, Tecumseh, and a japanese made
weedwhacker motor.
ERS

In article ,
says...


That said; if I needed that part, I
would go to somewhere where they sell lawnmower parts and buy one. My time has
a certain small amount of value to me.

Vaughn


That's it. When you need a part that's un-obtainable, make one. On a
part that takes 3 or 4 hours to make, and you can buy the thing for 10
or 20 dollars... forget it.

Jim Kovar
Vulcan, Mi

so, Japanese weeds are different from American weeds?

"Eric R Snow" wrote in message
...
On Tue, 08 Jun 2004 22:30:32 GMT, Ron Thompson
wrote:

On Tue, 08 Jun 2004 21:16:01 GMT, Ron Thompson
wrote:

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David
Thanks, that's the idea. But I was looking for the home built circuit.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Try www.modelflight.com/ignition.html
All I did was google for "electronic ignition circuit" This one is
battery operated. All the home made ones I seen use a battery.
ERS
Yeah, me too. Not much good on a lawnmower.
I thought I had the other one saved on my computer, but I can't find
it.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Ron- I have used the ones you can buy for about 10 bucks. Some in
plastic cases and others in metal cases. They all worked perfectly.
Interestingly, B&S used some kind of coil in their electronic ignition
to sense the magnet on the flywheel. And these ignitions were not that
reliable. The ones you buy must sense the voltage build up and fire
then. In a magneto ignition system the magnet needs to be passing the
coil when the points open to get a good spark. I don't know how the
retrofit systems know exactly when to fire. Different magnetos will
have different voltages. The first ones I saw had to be bought for the
right engine but the last one I bought said it would work on any
engine. And it worked on a B&S, Tecumseh, and a japanese made
weedwhacker motor.
ERS

How about this one: http://www.5bears.com/tim4.htm

Robert

"Ron Thompson" wrote in message
news
I saw a web page somewhere that had a circuit you could build to
replace the points and condenser on a lawnmower engine, but I lost it.
Can someone point me to it?
Thanks,


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

On Wed, 09 Jun 2004 01:40:14 GMT, "Jon Grimm"
wrote:
No, well, maybe, but that's not the point. The japanese ignitions were
different from the american ones. In fact, the american ones were
actually made in the USA.
ERS
so, Japanese weeds are different from American weeds?

"Eric R Snow" wrote in message
.. .
On Tue, 08 Jun 2004 22:30:32 GMT, Ron Thompson
wrote:

On Tue, 08 Jun 2004 21:16:01 GMT, Ron Thompson
wrote:

http://www.mfgsupply.com/m/c/31-8786.html?id=7qILfYVr
David
Thanks, that's the idea. But I was looking for the home built circuit.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Try www.modelflight.com/ignition.html
All I did was google for "electronic ignition circuit" This one is
battery operated. All the home made ones I seen use a battery.
ERS
Yeah, me too. Not much good on a lawnmower.
I thought I had the other one saved on my computer, but I can't find
it.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Ron- I have used the ones you can buy for about 10 bucks. Some in
plastic cases and others in metal cases. They all worked perfectly.
Interestingly, B&S used some kind of coil in their electronic ignition
to sense the magnet on the flywheel. And these ignitions were not that
reliable. The ones you buy must sense the voltage build up and fire
then. In a magneto ignition system the magnet needs to be passing the
coil when the points open to get a good spark. I don't know how the
retrofit systems know exactly when to fire. Different magnetos will
have different voltages. The first ones I saw had to be bought for the
right engine but the last one I bought said it would work on any
engine. And it worked on a B&S, Tecumseh, and a japanese made
weedwhacker motor.
ERS

How about this one: http://www.5bears.com/tim4.htm

Robert
Thanks, but it requires a battery.
To the "just buy it" crowd, I haven't found one locally and I haven't
worked for over two years. Money is scarce.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

Vaughn wrote:

I don't think that those "electronic ignitions" for lawnmower engines are
anything more than a hefty zener diode.

Now, why would a Zenner diode create the KV necessary for a spark?

I run a communications shop and we have drawers full of parts, some of
which would likely do the job just fine.

Do you use Zenner diodes for RF generation too?

Ted

"Ted Edwards" wrote in message
...
Vaughn wrote:

I don't think that those "electronic ignitions" for lawnmower
engines are
anything more than a hefty zener diode.

Now, why would a Zenner diode create the KV necessary for a spark?

It can act just like a set of points. It allows the voltage to rise to
a certain point, where it suddenly conducts, which collapses the magnetic
field. The collapsing field cuts the turns in the coil creating a spark. (I
think)

I run a communications shop and we have drawers full of parts, some
of
which would likely do the job just fine.

Do you use Zenner diodes for RF generation too?

Used mostly in DC power supply circuits and in circuit protection, come
in many voltages and physical sizes depending on power.

Vaughn



Ted

"Ron Thompson" wrote in message
...
How about this one: http://www.5bears.com/tim4.htm

To the "just buy it" crowd, I haven't found one locally and I haven't
worked for over two years.

Sorry to hear about that...

Money is scarce.
I understand. Then watch your local trash piles and scrounge (recycle)
what you need. Get someone who really knows to confirm, but I think most of the
lawnmowers that you find in the trash these days will have electronic ignition.
Electronic ignition *must* be cheaper than mechanical points.

Early in the summer is probably the best time of the year to find
junked-out lawnmowers as people are facing new heavy growth and junky lawnmowers
that barely made it through last year's season.

Vaughn



Vaughn




Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center,
USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

In article ,
Vaughn Simon wrote:

"Ted Edwards" wrote in message
...
Vaughn wrote:

I don't think that those "electronic ignitions" for lawnmower
engines are
anything more than a hefty zener diode.

Now, why would a Zenner diode create the KV necessary for a spark?

It can act just like a set of points. It allows the voltage to rise to
a certain point, where it suddenly conducts, which collapses the magnetic
field. The collapsing field cuts the turns in the coil creating a spark. (I
think)

I seem to remember something else for that purpose. Like a
zener, it does not turn on until it reaches a threshold voltage, but
unlike a zener, it does not remain at that voltage drop -- instead it
switches to an extremely low voltage drop. (Consider it to be like a
Zener diode connected between the gate an anode of an SCR, so when
things reach the right voltage, the SCR is turned on, and all the
current is dumped into the coil.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

How about this one: http://www.5bears.com/tim4.htm

Robert
Thanks, but it requires a battery.
To the "just buy it" crowd, I haven't found one locally and I haven't
worked for over two years. Money is scarce.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Ron,
Is this some kind of a special project you are working on, or do you
just want to get your lawnmower running? If it's a case of just
getting a mower running - provide some specifics like engine name,
numbers, etc., and either I or someone else can probably help you out.
Ken.

On Wed, 09 Jun 2004 18:35:33 GMT, "Vaughn Simon"
wrote:


"Ted Edwards" wrote in message
...
Vaughn wrote:

I don't think that those "electronic ignitions" for lawnmower
engines are
anything more than a hefty zener diode.

Now, why would a Zenner diode create the KV necessary for a spark?

It can act just like a set of points. It allows the voltage to rise to
a certain point, where it suddenly conducts, which collapses the magnetic
field. The collapsing field cuts the turns in the coil creating a spark. (I
think)


Got it backwards, kinda.
The votage increases, but there is no current until the zener fires.
The zener firing would BUILD the magnetic field, not collapse it.
Might still work if the field could build as fast as opening points
allows it to collapse. But some how you need to collapse that feild
too - which MAY happen effectively when the zener stops conducting.
Only problem is, the coil "rings" and the zener would likely false
trigger, killing the spark prematurely.

I suspect there is something a bit fancier than a Zener in the little
box.
I run a communications shop and we have drawers full of parts, some
of
which would likely do the job just fine.

Do you use Zenner diodes for RF generation too?

Used mostly in DC power supply circuits and in circuit protection, come
in many voltages and physical sizes depending on power.

Vaughn



Ted

On Wed, 09 Jun 2004 14:17:40 GMT, Ron Thompson
wrote:

How about this one: http://www.5bears.com/tim4.htm

Robert
Thanks, but it requires a battery.
To the "just buy it" crowd, I haven't found one locally and I haven't
worked for over two years. Money is scarce.

Last one I bought a couple of years ago cost me $9.95 at Princess
Auto. For that price I can't source the parts, pick them up, and plug
in the soldering iron, much less fiddle around trying to make it work,
and I'm a cheap beggar.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

Ron,
Is this some kind of a special project you are working on, or do you
just want to get your lawnmower running? If it's a case of just
getting a mower running - provide some specifics like engine name,
numbers, etc., and either I or someone else can probably help you out.
Ken.
I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.
I recalled this simple little circuit and got obsessed with finding it
again. Still no luck.
The zener and SCR sounds like it may be the ticket.
Thanks everyone for your responses.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

Ron,
Is this some kind of a special project you are working on, or do you
just want to get your lawnmower running? If it's a case of just
getting a mower running - provide some specifics like engine name,
numbers, etc., and either I or someone else can probably help you out.
Ken.
I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.
I recalled this simple little circuit and got obsessed with finding it
again. Still no luck.
The zener and SCR sounds like it may be the ticket.
Thanks everyone for your responses.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
Okay, I understand. Typically, though, a set of points (properly set)
and a *good* condenser should last *years and years* without any
problems. If the points are burning prematurely, changing the
condenser should cure the problem. Oil getting on the points is also
a "no-no" and can cause problems. Considering the "old" points and
condenser used in cars would go 12K miles, the intermittent use of a
lawnmower would seem to indicate almost "lifetime" duration - although
I realize that's not the case. I am familiar with the little unit
that replaces the points and condenser that is available retail -
somewhere around $16 and the only requirement for it is that the coil
is good - (no battery needed). I understand, from the paperwork
included with the unit, that it "fires" the plug dozens of times -
providing reliable ignition - just how it does this, I don't know.
I will "look around" a little for you to see if I find a schematic for
the setup you are looking for. Maybe I'll stumble onto something.
Ken.

There are two approaches to electronic ignition. One is to connect the
coil across a power source, let the current build up then interupt it.
V = L di/dt so voltage rises and in both primary and secondary until
plug fires. That's how pointed ignition systems worked. Early
"transistorized" ignitions simply replaced the points with a transistor
triggered by points or optical or magnetic sensor.

The second is capacitor discharge. Here a cap is charged up from an
appropriate power supply and discharged through the coil primary. These
are generally better.

The power source can be a vehicle electrical system or a coil and
magnet.

Pretty quick and dirty explanation but there is just no way you're going
to do it with just a Zenner diode.

(I've designed and built a few of both kinds.)

Ted

Ron Thompson wrote:

I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.

Replace the condenser. A bad condenser will either stop the engine dead
or just get it to eat points.

The zener and SCR sounds like it may be the ticket.

See my post elsewhere in this thread. That doesn't work.

Ted

On Thu, 10 Jun 2004 18:05:19 GMT, Ted Edwards
wrote:

There are two approaches to electronic ignition. One is to connect the
coil across a power source, let the current build up then interupt it.
V = L di/dt so voltage rises and in both primary and secondary until
plug fires. That's how pointed ignition systems worked. Early
"transistorized" ignitions simply replaced the points with a transistor
triggered by points or optical or magnetic sensor.

The second is capacitor discharge. Here a cap is charged up from an
appropriate power supply and discharged through the coil primary. These
are generally better.

The power source can be a vehicle electrical system or a coil and
magnet.

Pretty quick and dirty explanation but there is just no way you're going
to do it with just a Zenner diode.

(I've designed and built a few of both kinds.)

Ted

Ted-I've always seen these types of diodes called zener, just one "n",
not two. Are they really called zenner?
ERS

In article , Ted Edwards says...

The zener and SCR sounds like it may be the ticket.

See my post elsewhere in this thread. That doesn't work.

A zen(n)er alone obviously won't work. That plus an
SCR to switch the current sounds almost plausible....

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Ron Thompson wrote:

I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.

Replace the condenser. A bad condenser will either stop the engine dead
or just get it to eat points.

The zener and SCR sounds like it may be the ticket.

See my post elsewhere in this thread. That doesn't work.

Ted
Yes, I should have said points and condenser. The end of the condenser
is the lower contact of the points set.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)

On Thu, 10 Jun 2004 07:33:00 GMT, Ron Thompson
wrote:

Ron,
Is this some kind of a special project you are working on, or do you
just want to get your lawnmower running? If it's a case of just
getting a mower running - provide some specifics like engine name,
numbers, etc., and either I or someone else can probably help you out.
Ken.
I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.
I recalled this simple little circuit and got obsessed with finding it
again. Still no luck.
The zener and SCR sounds like it may be the ticket.
Thanks everyone for your responses.
In all my years of mowing with junk mowers, I have never replaced
points; touched them up on the grinder a couple times, freed up the
plunger occasionally and replaced the plug once or twice. Most I ever
paid for a mower was $15.00 but that one lasted 22 years mowing a
minimum of three lawns full time.
Gerry :-)}
London, Canada

I will keep an eye out for a junked engine with an electronic module
in it. i have been curious about that too.

Dan



Ron Thompson wrote in message I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.
I recalled this simple little circuit and got obsessed with finding it
again. Still no luck.
The zener and SCR sounds like it may be the ticket.
Thanks everyone for your responses.

Ron Thompson

In article ,
jim rozen wrote:
In article , Ted Edwards says...

The zener and SCR sounds like it may be the ticket.

See my post elsewhere in this thread. That doesn't work.

A zen(n)er alone obviously won't work. That plus an
SCR to switch the current sounds almost plausible....

Only if you can depend on the ringing to turn the SCR off again.
Not sure whether I would bet on that.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 9 Jun 2004 19:43:32 -0400, (DoN. Nichols) wrote:
I seem to remember something else for that purpose. Like a
zener, it does not turn on until it reaches a threshold voltage, but
unlike a zener, it does not remain at that voltage drop -- instead it
switches to an extremely low voltage drop. (Consider it to be like a
Zener diode connected between the gate an anode of an SCR, so when
things reach the right voltage, the SCR is turned on, and all the
current is dumped into the coil.

That would be a Diac.

Gary

On Fri, 11 Jun 2004 16:08:41 GMT, the renowned
(Gary Coffman) wrote:

On 9 Jun 2004 19:43:32 -0400, (DoN. Nichols) wrote:
I seem to remember something else for that purpose. Like a
zener, it does not turn on until it reaches a threshold voltage, but
unlike a zener, it does not remain at that voltage drop -- instead it
switches to an extremely low voltage drop. (Consider it to be like a
Zener diode connected between the gate an anode of an SCR, so when
things reach the right voltage, the SCR is turned on, and all the
current is dumped into the coil.

That would be a Diac.

Gary

Or SBS, SUS, or SIDAC. The first two are pretty much obsolete. The
latter are used in ignition systems. Diacs are typically spec'd for
triggering larger thyristors.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Eric R Snow wrote:

Ted-I've always seen these types of diodes called zener, just one "n",
not two. Are they really called zenner?

You are right and I am wrong. I just looked it up. It's Zener.

BTW, NEVER trust my spelling, especially when it comes to ddoouubbllee
leters. :-)

Ted

In article , Ted Edwards says...

I just looked it up. It's Zener.

Maybe you were thinking of Gunnnn diodes....

Jim

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please reply to:
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jim rozen wrote:

Maybe you were thinking of Gunnnn diodes....

Actually, I new Dr. Gunn. He was a prof in the Solid State Physics
group at University of British Columbia. It was told around the Physics
department that on a trip to San Fransisco in his Jag, a piston
colapsed. He pulled over to the side of the road, got out the tool kit
and removed the piston and rod from that cylinder. He then carried on
on seven to 'Frisco where he could get a replacement piston.

Ted

In article , Ted Edwards says...

Actually, I new Dr. Gunn. He was a prof in the Solid State Physics
group at University of British Columbia. It was told around the Physics
department that on a trip to San Fransisco in his Jag, a piston
colapsed. He pulled over to the side of the road, got out the tool kit
and removed the piston and rod from that cylinder. He then carried on
on seven to 'Frisco where he could get a replacement piston.

Ian Gunn worked at IBM research for some time.
Apparently he had quite an attraction to earth
moving equipment (backhoes) as well.

Jim

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please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
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On 14 Jun 2004 13:30:41 -0700, jim rozen
calmly ranted:

In article , Ted Edwards says...

Actually, I new Dr. Gunn. He was a prof in the Solid State Physics
group at University of British Columbia. It was told around the Physics
department that on a trip to San Fransisco in his Jag, a piston
colapsed. He pulled over to the side of the road, got out the tool kit
and removed the piston and rod from that cylinder. He then carried on
on seven to 'Frisco where he could get a replacement piston.

Uh, Ted. How did he get the oil pressure to stay up without a
rod in place (to stop the gaping oil holes in the crank)?

That sounds like an old story, back when you could see the engine
as a separate entity from the underbonnet.


Ian Gunn worked at IBM research for some time.
Apparently he had quite an attraction to earth
moving equipment (backhoes) as well.

Who doesn't? arr arr arr

--
Don't forget the 7 P's:
Proper Prior Planning Prevents ****-Poor Performance
----------------------------------------------------
http://diversify.com Website Application Programming

Larry Jaques wrote:

Uh, Ted. How did he get the oil pressure to stay up without a
rod in place (to stop the gaping oil holes in the crank)?

I have no idea. Hose clamp on the crank covering the oil hole?

That sounds like an old story, back when you could see the engine
as a separate entity from the underbonnet.

Early '50s.

Ian Gunn worked at IBM research for some time.
Apparently he had quite an attraction to earth
moving equipment (backhoes) as well.

Who doesn't? arr arr arr

Not many!
It was summer. The walls were poured, damp-proofed and insulated. Time
to
backfill. We could have someone come in and do it in a day for around
Cdn$400. For the same money, we could rent a Bobcat for a week. This
was
just before the July long weekend and we had a bunch of visitors
comming.

We decided to go the rental route. Well, our guests were unanimous that
that
Bobcat was more fun than a trip to Disney Land. There was a constant
line up
of eager drivers of all ages.

The back filling got done along with some other earth moving projects.

Ted

On Mon, 14 Jun 2004 17:58:45 -0700, Larry Jaques
wrote:

On 14 Jun 2004 13:30:41 -0700, jim rozen
calmly ranted:

In article , Ted Edwards says...

Actually, I new Dr. Gunn. He was a prof in the Solid State Physics
group at University of British Columbia. It was told around the Physics
department that on a trip to San Fransisco in his Jag, a piston
colapsed. He pulled over to the side of the road, got out the tool kit
and removed the piston and rod from that cylinder. He then carried on
on seven to 'Frisco where he could get a replacement piston.

Uh, Ted. How did he get the oil pressure to stay up without a
rod in place (to stop the gaping oil holes in the crank)?

I actually saw a guy do it in our lot back in 1969. A 235 Chevy 6 in a
'55 Bel_Air from Newfoundland pulled into the station, knocking like a
son-of-a-gun. The young fellow bought a pan gasket and a rad hose
clamp and borrowed a couple of wrenches. He crawled under the car with
one set of wheels on the curb, dropped the pan, unbolted the offending
con-rod, and jammed the piston up in the cyl with a block of wood. He
then took off his belt, cut off the end, and wrapped it around the
crankpin, clamping it with the rad hose clamp.
He bolted the pan back on, filled it up with oil, and left Elmira
Ontario for Come-By Chance or Joe Bat's Arm on the Granite Planet.

So it CAN be done.

That sounds like an old story, back when you could see the engine
as a separate entity from the underbonnet.


Ian Gunn worked at IBM research for some time.
Apparently he had quite an attraction to earth
moving equipment (backhoes) as well.

Who doesn't? arr arr arr

On Tue, 15 Jun 2004 02:28:04 GMT, Ted Edwards
calmly ranted:

Larry Jaques wrote:
Who doesn't? arr arr arr

Not many!
It was summer. The walls were poured, damp-proofed and insulated. Time
to
backfill. We could have someone come in and do it in a day for around
Cdn$400. For the same money, we could rent a Bobcat for a week. This
was
just before the July long weekend and we had a bunch of visitors
comming.

We decided to go the rental route. Well, our guests were unanimous that
that
Bobcat was more fun than a trip to Disney Land. There was a constant
line up
of eager drivers of all ages.

Sounds like a blast. I've never driven a tractor or bobcat.
I'll have to ask that steam roller owner if I can stand on for
the parade if his little boy isn't with him next week at the
Pottsville, OR steam/tractor shindig. I can't believe the prices
they get for those old hit 'n miss engines. thud

--
Don't forget the 7 P's:
Proper Prior Planning Prevents ****-Poor Performance
----------------------------------------------------
http://diversify.com Website Application Programming