Kettering Ignition Question

Hi,

Most texts and web sites gloss over the secondary, or HT circuit, in an automotive points based ignition circuit. Explanations simply say that voltage produced at the HT post of the secondary winding enables the spark to jump to ground, but do not explain the circuit from the other end of the secondary winding to complete the circuit.

The layout of the circuit I am considering is where the -ve terminal of the coils is connected to both the primary and secondary windings. I hope the ascii rendering below explains the circuit.

As the points are open when the HT voltage is induced in the secondary, it seems to me that the only routes are either through the condenser or the battery.

I have only seen the role of the condensor discussed in terms of the back EMF from the primary.

Thanks, Clive.

+ve HT distrib ----------o--c||C--O----------=AD()------------ | c||C | | Primary c||C Secondary | | c||C o | |--| [] Spark Plug [+] | . gap [ ] -ve o | [ ] Battery | Grnd --- [ ] |----- - [-] | | | Points / =3D=3D=3D Condensor | / | --- Grnd |----- - |=20 Grnd ---=20 -
Reply to
Clive
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Compared to the voltage produced by the HT winding, the battery=20 voltage is essentially zero, and therefore, the positive battery=20 terminal is essentially a ground connection.

If the LT coil is phased correctly with the HT coil, it adds another=20

1% or so to the HT output voltage.

Its primary (excuse the pun) purpose is to control the rate of rise of=20 voltage as the points open, to minimize arching (which damages the=20 points and consumes energy that would otherwise go into the plug=20 spark). It has a minor effect on the spark characteristics at the plug.

Reply to
John Popelish

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Reply to
kell

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