Kettering Ignition Question

[Clive]

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----------­()------------
| c||C |
| Primary c||C Secondary |
| c||C o
| |--| [] Spark Plug
[+] | . gap
[ ] -ve o |
[ ] Battery | Grnd ---
[ ] |----- -
[-] | |
| Points / === Condensor
| / |
--- Grnd |-----
- |
Grnd ---
-

 

[kell]

Clive wrote:

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----------­()------------
| c||C |
| Primary c||C Secondary |
| c||C o
| |--| [] Spark Plug
[+] | . gap
[ ] -ve o |
[ ] Battery | Grnd ---
[ ] |----- -
[-] | |
| Points / === Condensor
| / |
--- Grnd |-----
- |
Grnd ---
-