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that was an exellent description of the ign. sys. coil saturation: current flowing through a wire induces a mag field around it. mag field passing through a wire induces a voltage in it. the movement of the field is the key. a static mag field dosent affect the electron flow. in the coil as current flows in the primary,a mag field is created. at some point the building mag field will oppose the incoming current to the point of stopping it-saturation. when the points open, the stored charge in the condenser pushes the current back through the primary-cauring a rapid collapse of the mag field. that moving mag field induces a voltage in the sec. windings. since the sec are about 1000 times more, the voltage is also much higher than the pri. this happens because both windings are around the same iron core. whew
 

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so ... you know a little about sound equipment. do you know what impedance is? this has abearing on all this. the mag field will stop expanding when current stops flowing. a counter electromotive force is created by the mag field induced. when it equals the electromotive force moving the current, flow stops. it's like the more you try to put in the more resistance to putting in occures. the condenser(capacitor) is like an accumulater in hydrolics. sort of a spring loaded can. you can fill it up, but when you open it the contents will spray out. p.s. it's main function is to help the coil mmake a spark. if it is not properly matched to the ign sys. point pitting can occure.[neg metal on the neg contact means not a bigg enough capacitor]
 

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the condenser will charge to over 100v at rpm. when the points open there's 12v on the + side of the coil. 100v on the neg side will cause current to flow back through the coil. this "back flow" is what causes the rapid mag field collaps.
 

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if you think of the mag field as the rings formed when you throw a pebble in a pond. always expanding away from the pebble. now imagine them reversing back to the center. thats the collapsing mag field
 

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the compression tester isn't very accurate. cranking speed, fuel in cyls, oil incyls ,etc can vary readings. running compression test is easier and more usefull. with engine running- short each cyl. and record rpm drop. large rpm drop- most efficient cyl. least rpm drop-least efficient cyl. you can short cyls by putting pieces of hose on the cap, put plug wires in the hoses. use your test light to touch the hose. spark will go through the light to ground. hoses should be about 2" long.
 

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the short pieces of hose will act as a conductor to pass the spark to the plugs, but if you touch the test light to the hose the path of least resistance is through the test light shorting the spark to ground . the cyl hose you touch will stop running. this will not hurt any part of the sys, and is an accepted way of doing a cyl bal test. cheap too
 

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oh-- tesla also invented the radio(not marconi) he also implemented the first hidroelectric plant at niagra falls which is still in use. edison invented the light bulb, but tesla figured out how to get power to the people to use it
 

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cyl. bal test dosen't involve the timing light. yes the spark will go through the hose and the engine will run normally. the hoses just need to fit into dist end of the plug wire boot and over the stud on the dist cap. with your test light conneced to the neg bat post(test the pointed end on pos post for light) now with eng. running-touching the pointed end of the test light to a hose will kill that cyl. using the timing light varifies spark in the plug wire, but doesn't varify cyl contribution to eng. power. spark may be there, it doesn't mean the cyl is making power
 
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