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After I wrote the following on the stationary-engine maillist,
It makes sense to have a capacitor across the contacts to reduce erosion on the surfaces. It also may well goose up the voltage a bit too. I will be experimenting on this because I now have three engines in need of a buzz coil.
I stirred up a bees' nest and observed the following comments:

From: Ron
Subject: Re: BUZZ Coils
I don't think I have heard this expression in relation to capacitors before. I always thought the capacitor served as a storage area for electrons which would then surge across the primary coil at the opening or closing of the ignition points, causing a stronger magnetic pulse in the soft iron core which, in turn, creates a flow of electrons at higher voltage to emerge from the secondary winding. By God, you are right! Goosing up the voltage is just what it does. Such a terse yet artistic descriptive phrase! Thank you for your contribution to my electrical vocabulary.

From: Robert Holcomb
Subject: BUZZ Coils
Gotta jump in on this one.. A couple of years ago when my 1.5 H.P.Fairbanks dishpan quit, we checked the coil and it was dead. I was ready to shell out for a rebuilt one when this older gentleman stopped in. He went back to his truck and brought back a standard lawn mower condenser. He then strapped the condenser to the 8-32 screw and hooked up the lead to the screw that adjusts the points. I do not own a hotter coil now and the cost was 2.00 to 3.00 dollars U.S.

From: Jerry Mac Martin
Subject: Re: BUZZ Coils
Bob's right Harry there's a capacitor inside the Buzz coil mounted next to the high tension coil. You might like to refer to GEM Nov.1988 Page 7 and June 1988 Page31 on how to make a Buzz coil. The average consensus is, that a capacitor value of 0.5 to 1 mfd. is sufficient and it should be rated at 2 to 400 volts.

From: John Morton
May I share a thought with you concerning condensers. A condenser is (supposedly) infinitely resistant to DC. BUT, when a DC is dumped into a condenser by the opening or closing of the points, it roars into the condenser, stops, backs up, roars in again, stops, backs up, etc, like waves on a beach on an incoming tide. A condenser cushions the flow of electrons in a circuit like a spring/shock combo. Therefore, when a point makes or breaks, the coil is subjected to what seems to be AC instead of DC. The lowly condenser acts like an oscillator circuit and this combined with the step up action of the coil is what jumps up the volts and fires the plug. PROOF? put a HUGE capacitor or a TINY capacitor in instead of the right sort. Too big or small doesn't do the job. An ignition circuit needs a condenser that is matched to the coil, and the voltage source, and the RPM of the motor. Too big acts like none at all, and too small acts like none at all. In addition to the capacitance of the condenser, it is important that it be designed to ring like a bell, for lack of a better word). Capacitor design / ignition design somehow takes into account the natural frequency of the capacitor.
Ignition condensers are actually pretty special little gizmos. I took electronics in High School many years ago and this was the theory then. There may be an entirely different explanation by now.
John Morton

From: Rob Skinner
1. Never place cellophane, paper, or any foreign material between the breaker points for the purposes of timing. Doing so will contaminate the points. Don't believe me? Get a high power magnifier and look at that match book cover. It looks like a hairy forest! Yeow. You don't want that junk getting on the points. Set the points using a timing light, buzzer, or sight.
2. If using a timing light, buzzer, or ohm meter to set the timing, the primary lead wire from the coil must be disconnected at the breaker points. If the coil wire is not disconnected, when the points open, current will flow through the primary side of the coil. This will induce a magnetic field, thereby weakening the magnet. Demagnetizing can also occur from testing the windings while they are in place.
3. If you are cranking over an engine without the spark plug connected, never disconnect the wire from the mag nor let the spark plug wire hang. Always ground the plug wire to the engine block. To do otherwise can cause excessive voltage in the secondary winding, and a breakdown of the insulation on the wires.
Rob Skinner

From: Charles R. Bryant
Subject: Re: BUZZ Coils
>>Quoted from the late Bob Learned: Believe it or not, these coils can be repaired and the condenser replaced. I have recently seen an ad that advertised this rebuild service. I believe it may have been in and Antique Automobile magazine. It's a problem because most of these coils are filled with tar and it gets pretty messy inside.
The guy that rebuilds buzz coils and advertisesin GEM is
Bob Betlach
101 Worthy Circle
Fenton, MO 63026-2764
Bob is also a member of our club. He does a good job.
Harold Bowden, another club member (who is the mfg. of Kwik Poly) used to be a big collector of Model T's. He has a buzz coil tester so I take all my buzz coils to him for testing. His auction a couple of years back of Model T's and parts took over 2 days.

From: Bill Dickerson
Subject: Re: BUZZ Coils
Here is the scoop:
Current in primary winding causes a magnetic field around the coil and iron core, (as any electric coil will do). This magnet field causes the iron core to become a magnet, pulling the metal movable point down, causing the points to open.
Circuit in primary winding broken, magnetic field collapses - this SUDDEN collapse of the magnetic field induces a voltage in the secondary winding - this voltage is higher since there are more windings in the secondary for the magnetic field to act upon.
It is the SUDDEN collapse that causes the current in the secondary. Arching would cause a slow, or un-smooth collapse, thus lowering the strength of the field collapse, and cause either a low, or no voltage to be induced.
Once the field collapses, the iron core is no longer a magnet, and the points are released to close again.
Reason for arching - the collapse in the field also induces current opposite to the original in the primary winding. It is this current that causes the arching.
A condenser is able to absorb this excess, and higher electron flow, and store it until the circuit is made again, where it is released harmlessly. Without the condenser, the current would literally "bounce" back and forth in the primary winding, prohibiting a clean collapse of the magnetic field. This can all be witnessed by using a scope on the system.

From: Harold Kuret & Cindy Blair
Subject: Re: BUZZ Coils
I believe that condensers can go bad for at least 2 reasons. One is that they are able to absorb the electron flow quickly but discharge it slowly. The other is that they absorb the electron flow slowly but discharge it quickly. I have had condensers that can not discharge the electrons quickly. They are very frustrating because they will give you a good spark most of the time.
An elderly friend of mine has a coil and condenser tester. You plug it into 115V current and hook your coil or condenser to the test leads. It buzzes away like a Buzz coil would. It has an area where you can view the spark as well as a meter on it. I don't know exactly how it works. I do know that I can take any kind of a coil or condenser to him and he can quickly tell what's going on.
Does anyone out there know where to get or how to make such a tester.
Harold Kuret,
Lynden, Ont. Canada

From: George Best
Subject: Testing Webster Tri-polar
The following info is taken from an old Webster repair manual:
"Testing magneto for voltage."
Remove the inductor springs and spring arm and drive the magneto at 500 RPM. [You need a variable speed lathe, drill press, or motor connected to the magneto shaft to turn it at the needed 500 rpm.]
Check the voltage generated by the magneto with a AC voltmeter. If the voltage produced by the magneto is at or above the amounts listed below, the mag is good.
If the voltage is low, remagnetize the magneto and test again. If after remagnetizing it is still low, then the coil or magnet is bad.
Type   Volts

M      8.5
MM     13
K      9.5
L      11.5
JZ     11
JY     15
PY     20
1A     9
1E     25
1F     14
2C     12

Note: voltage reading for 1E may not come up to 25 volts unless the voltmeter is of the high resistance type. On an ordinary voltmeter this reading will probably show around 17 volts.
George Best
Portland, OR

Dave Rotigel also made a valid point about grounding a magneto. If you rebuild and repaint the engine, make sure the mounting bolts and contact area between the magneto and the engine casting are clean bare metal. Of course that goes for all other contacts and connections in the circuit as well. NEXT PAGE: >

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