Re: gas engine question

The coil must have been faulty. Power on - power off has no effect. Once the coil is powered and has established its magnetic field the current drops to near zero - stays flowing just enough to maintain the field, much like a solenoid, except insted of pulling in a core as is the case with a solenoid, this field charges a secondary field which contains many more windings. The principle of operation is that the points opening disrupt the tiny current that maintains the primary field, which causes the primary field to instantly collapses - creating a voltage spike in the secondary coil of many thousand volts, which jumps at the spark plug to ground. Usually the coils are encapsulated and contain small amounts of resin type insulation - a fault in the right spot could heat the coil to a point of ignition of the resin and, yes,cook it or blow it to pieces. The usual mode of failure however is a break in the circuit rather than a short - a break would simply leave the coil useless - out of commission. No need to do anything but get another coil and install it.

Sorry but this is wrong. Current most certainly does not drop once the magnetic field is saturated. No magic is available that changes the resistance of a copper wire. Simply put, with the points closed current flow and the coil gets hot. Ted Wrobel Cal 33 Celebration Newport, RI From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] Sent: Thursday, July 03, 2014 8:55 AM To: Ca… [at] yahoogroups.com Subject: [Cal_Boats] Re: gas engine question The coil must have been faulty. Power on - power off has no effect. Once the coil is powered and has established its magnetic field the current drops to near zero - stays flowing just enough to maintain the field, much like a solenoid, except insted of pulling in a core as is the case with a solenoid, this field charges a secondary field which contains many more windings. The principle of operation is that the points opening disrupt the tiny current that maintains the primary field, which causes the primary field to instantly collapses - creating a voltage spike in the secondary coil of many thousand volts, which jumps at the spark plug to ground. Usually the coils are encapsulated and contain small amounts of resin type insulation - a fault in the right spot could heat the coil to a point of ignition of the resin and, yes,cook it or blow it to pieces. The usual mode of failure however is a break in the circuit rather than a short - a break would simply leave the coil useless - out of commission. No need to do anything but get another coil and install it.

Yes, the only magic that changes the resistance is heat. As temp goes up, so does resistance. However, the point you were trying to get across is still valid. Cheers! :-) Mike, Cal-20 Calamity On July 3, 2014 6:03:14 AM PDT, "'Ted Wrobel' tw… [at] tacticaltech.com [Cal_Boats]" <Ca… [at] yahoogroups.com> wrote: >Sorry but this is wrong. Current most certainly does not drop once the >magnetic field is saturated. No magic is available that changes the >resistance of a copper wire. Simply put, with the points closed current >flow >and the coil gets hot. > > > >Ted Wrobel > >Cal 33 Celebration > >Newport, RI > > > > > >From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] >Sent: Thursday, July 03, 2014 8:55 AM >To: Ca… [at] yahoogroups.com >Subject: [Cal_Boats] Re: gas engine question > > > > > >The coil must have been faulty. Power on - power off has no effect. >Once the >coil is powered and has established its magnetic field the current >drops to >near zero - stays flowing just enough to maintain the field, much like >a >solenoid, except insted of pulling in a core as is the case with a >solenoid, >this field charges a secondary field which contains many more windings. >The >principle of operation is that the points opening disrupt the tiny >current >that maintains the primary field, which causes the primary field to >instantly collapses - creating a voltage spike in the secondary coil of >many >thousand volts, which jumps at the spark plug to ground. > > > >Usually the coils are encapsulated and contain small amounts of resin >type >insulation - a fault in the right spot could heat the coil to a point >of >ignition of the resin and, yes,cook it or blow it to pieces. The usual >mode >of failure however is a break in the circuit rather than a short - a >break >would simply leave the coil useless - out of commission. > > > >No need to do anything but get another coil and install it. --

Right you are. Left that part out, thanks. Ted From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] Sent: Thursday, July 03, 2014 9:06 AM To: Ca… [at] yahoogroups.com Subject: RE: [Cal_Boats] Re: gas engine question Yes, the only magic that changes the resistance is heat. As temp goes up, so does resistance. However, the point you were trying to get across is still valid. Cheers! :-) Mike, Cal-20 Calamity On July 3, 2014 6:03:14 AM PDT, "'Ted Wrobel' tw… [at] tacticaltech.com <mailto:tw… [at] tacticaltech.com> [Cal_Boats]" <Ca… [at] yahoogroups.com <mailto:Ca… [at] yahoogroups.com> > wrote: Sorry but this is wrong. Current most certainly does not drop once the magnetic field is saturated. No magic is available that changes the resistance of a copper wire. Simply put, with the points closed current flow and the coil gets hot. Ted Wrobel Cal 33 Celebration Newport, RI From: Ca… [at] yahoogroups.com <mailto:Ca… [at] yahoogroups.com> [mailto:Ca… [at] yahoogroups.com] Sent: Thursday, July 03, 2014 8:55 AM To: Ca… [at] yahoogroups.com <mailto:Ca… [at] yahoogroups.com> Subject: [Cal_Boats] Re: gas engine question The coil must have been faulty. Power on - power off has no effect. Once the coil is powered and has established its magnetic field the current drops to near zero - stays flowing just enough to maintain the field, much like a solenoid, except insted of pulling in a core as is the case with a solenoid, this field charges a secondary field which contains many more windings. The principle of operation is that the points opening disrupt the tiny current that maintains the primary field, which causes the primary field to instantly collapses - creating a voltage spike in the secondary coil of many thousand volts, which jumps at the spark plug to ground. Usually the coils are encapsulated and contain small amounts of resin type insulation - a fault in the right spot could heat the coil to a point of ignition of the resin and, yes,cook it or blow it to pieces. The usual mode of failure however is a break in the circuit rather than a short - a break would simply leave the coil useless - out of commission. No need to do anything but get another coil and install it. --

The magnetic field is proportional to the current and will build slowly when the points are closed due to the inductance of the coil. It will continue to increase until limited by some resistance which better be more than the copper resistance, thus the ballast resistor. The voltage on the secondary is proportional to the rate of change of the magnetic field. When the points open, the combination of the capacitor on the primary and the coil product a very fast change in that field which creates the firing spark. The only other detail is that the current in a coil cannot change instantaneously. That is what the capacitor across the points is for. That creates a place for the current to go when the points are opened. Without that, the current would continue to flow in the form of a spark across the points which would then wear out quickly. Or something close to this :-) Allen On Thu, Jul 3, 2014 at 7:00 AM, 'Ted Wrobel' tw… [at] tacticaltech.com [Cal_Boats] <Ca… [at] yahoogroups.com> wrote: > > > Right you are. Left that part out, thanks. > > > > Ted > > > > > > *From:* Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] > *Sent:* Thursday, July 03, 2014 9:06 AM > *To:* Ca… [at] yahoogroups.com > *Subject:* RE: [Cal_Boats] Re: gas engine question > > > > > > Yes, the only magic that changes the resistance is heat. As temp goes up, > so does resistance. However, the point you were trying to get across is > still valid. > Cheers! :-) > Mike, Cal-20 Calamity > > On July 3, 2014 6:03:14 AM PDT, "'Ted Wrobel' tw… [at] tacticaltech.com > [Cal_Boats]" <Ca… [at] yahoogroups.com> wrote: > > > > Sorry but this is wrong. Current most certainly does not drop once the > magnetic field is saturated. No magic is available that changes the > resistance of a copper wire. Simply put, with the points closed current > flow and the coil gets hot. > > > > Ted Wrobel > > Cal 33 Celebration > > Newport, RI > > > > > > *From:* Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com > <Ca… [at] yahoogroups.com>] > *Sent:* Thursday, July 03, 2014 8:55 AM > *To:* Ca… [at] yahoogroups.com > *Subject:* [Cal_Boats] Re: gas engine question > > > > > > The coil must have been faulty. Power on - power off has no effect. Once > the coil is powered and has established its magnetic field the current > drops to near zero - stays flowing just enough to maintain the field, much > like a solenoid, except insted of pulling in a core as is the case with a > solenoid, this field charges a secondary field which contains many more > windings. The principle of operation is that the points opening disrupt the > tiny current that maintains the primary field, which causes the primary > field to instantly collapses - creating a voltage spike in the secondary > coil of many thousand volts, which jumps at the spark plug to ground. > > > > Usually the coils are encapsulated and contain small amounts of resin type > insulation - a fault in the right spot could heat the coil to a point of > ignition of the resin and, yes,cook it or blow it to pieces. The usual mode > of failure however is a break in the circuit rather than a short - a break > would simply leave the coil useless - out of commission. > > > > No need to do anything but get another coil and install it. > > > -- > Sent from my Android device with K-9 Mail. Please excuse my brevity. > > >

Very well put! Thanks Allen. Mike, Cal-20, Calamity On July 3, 2014 7:17:29 AM PDT, "Allen Edwards al… [at] gmail.com [Cal_Boats]" <Ca… [at] yahoogroups.com> wrote: >The magnetic field is proportional to the current and will build slowly >when the points are closed due to the inductance of the coil. It will >continue to increase until limited by some resistance which better be >more >than the copper resistance, thus the ballast resistor. The voltage on >the >secondary is proportional to the rate of change of the magnetic field. >When the points open, the combination of the capacitor on the primary >and >the coil product a very fast change in that field which creates the >firing >spark. The only other detail is that the current in a coil cannot >change >instantaneously. That is what the capacitor across the points is for. > That creates a place for the current to go when the points are opened. >Without that, the current would continue to flow in the form of a spark >across the points which would then wear out quickly. Or something >close to >this :-) > >Allen > > >On Thu, Jul 3, 2014 at 7:00 AM, 'Ted Wrobel' tw… [at] tacticaltech.com >[Cal_Boats] <Ca… [at] yahoogroups.com> wrote: > >> >> >> Right you are. Left that part out, thanks. >> >> >> >> Ted >> >> >> >> >> >> *From:* Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] >> *Sent:* Thursday, July 03, 2014 9:06 AM >> *To:* Ca… [at] yahoogroups.com >> *Subject:* RE: [Cal_Boats] Re: gas engine question >> >> >> >> >> >> Yes, the only magic that changes the resistance is heat. As temp goes >up, >> so does resistance. However, the point you were trying to get across >is >> still valid. >> Cheers! :-) >> Mike, Cal-20 Calamity >> >> On July 3, 2014 6:03:14 AM PDT, "'Ted Wrobel' >tw… [at] tacticaltech.com >> [Cal_Boats]" <Ca… [at] yahoogroups.com> wrote: >> >> >> >> Sorry but this is wrong. Current most certainly does not drop once >the >> magnetic field is saturated. No magic is available that changes the >> resistance of a copper wire. Simply put, with the points closed >current >> flow and the coil gets hot. >> >> >> >> Ted Wrobel >> >> Cal 33 Celebration >> >> Newport, RI >> >> >> >> >> >> *From:* Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com >> <Ca… [at] yahoogroups.com>] >> *Sent:* Thursday, July 03, 2014 8:55 AM >> *To:* Ca… [at] yahoogroups.com >> *Subject:* [Cal_Boats] Re: gas engine question >> >> >> >> >> >> The coil must have been faulty. Power on - power off has no effect. >Once >> the coil is powered and has established its magnetic field the >current >> drops to near zero - stays flowing just enough to maintain the field, >much >> like a solenoid, except insted of pulling in a core as is the case >with a >> solenoid, this field charges a secondary field which contains many >more >> windings. The principle of operation is that the points opening >disrupt the >> tiny current that maintains the primary field, which causes the >primary >> field to instantly collapses - creating a voltage spike in the >secondary >> coil of many thousand volts, which jumps at the spark plug to ground. >> >> >> >> Usually the coils are encapsulated and contain small amounts of resin >type >> insulation - a fault in the right spot could heat the coil to a point >of >> ignition of the resin and, yes,cook it or blow it to pieces. The >usual mode >> of failure however is a break in the circuit rather than a short - a >break >> would simply leave the coil useless - out of commission. >> >> >> >> No need to do anything but get another coil and install it. >> >> >> -- >> Sent from my Android device with K-9 Mail. Please excuse my brevity. >> >> >> --

A coil is an inductive electrical circuit which opposes the flow of current through it. The current limiting factor is due to the presence of the self induced emf within the inductor as a result of the growth of magnetic flux, (Lenz’s Law). After a time the voltage source neutralizes the effect of the self induced emf, the current flow, quickly reduced from a theoretical initial short circuit, becomes constant and the induced current and field are reduced to zero.

This is incorrect. A coil resists changes in current so initially draws little current and ultimately will draw infinite current. In the real world, a coil will include some resistance along with the inductance and that will limit the current. Specifically, for an inductor V = L*di/dt which says that the applied voltage is proportional to the change in current with time. Said another way, applying a voltage to a coil will cause the current to increase as long as the voltage is applied. This is critical to how the high voltage is created as opening the points causes a sudden change in the current which then makes a huge voltage which is what fires the spark plugs. If you want a device that is initially a short circuit and has the current reduce to zero after the current flows, you want a capacitor. A capacitor is more or less the opposite of an inductor. On Sat, Jul 5, 2014 at 6:47 AM, du… [at] aim.com [Cal_Boats] < Ca… [at] yahoogroups.com> wrote: > > > A coil is an inductive electrical circuit which opposes the flow of > current through it. The current limiting factor is due to the presence of > the self induced emf within the inductor as a result of the growth of > magnetic flux, (Lenz’s Law). After a time the voltage source neutralizes > the effect of the self induced emf, the current flow, quickly reduced > from a theoretical initial short circuit, becomes constant and the > induced current and field are reduced to zero. > >

Correction - I was wrong - The induction circuit resists CHANGE in current flow - I need to open my old dusty books and rush up on all this - sorry for the confusion. From: dutchessc22 <du… [at] aim.com> To: Cal_Boats <Ca… [at] yahoogroups.com> Sent: Sat, Jul 5, 2014 9:47 am Subject: Re: gas engine question A coil is an inductive electrical circuit which opposes the flow of current through it. The current limiting factor is due to the presence of the self induced emf within the inductor as a result of the growth of magnetic flux, (Lenz’s Law). After a time the voltage source neutralizes the effect of the self induced emf, the current flow, quickly reduced from a theoretical initial short circuit, becomes constant and the induced current and field are reduced to zero.