Thread: Amateur auto electrician needs advice

I suppose it depends on what you're trying to achieve. Sounds like homework and looks like it needs a push start.

Originally Posted by BradC

I suppose it depends on what you're trying to achieve. Sounds like homework and looks like it needs a push start.

I thought the goal was obvious!

Trying to achieve 12v to the coil at startup, then revert to 9v.

It wasn’t obvious to me (and I’m an electronics tech) so I didn’t comment. Now that I know, it’s still not obvious.

I’d need to redraw the circuit so that it makes sense.

Making no comment on the drawing, but shouldn't that " capacitor 9V" be a ballast resistor?

no its not, thats the setup for a ballested ignition.

IF you use a capacitor instead of a ballast resistor in the way you are setting it up the engine will run until the capacitor charges and then it will stop as the spark fails.

there are 2 places a capacitor gets used on a typical points system.

1 is in the points and its there to stop arcing, the other is usually on the alternator or near the coil and its used as a noise surpressor.

Originally Posted by Alpal

I have drawn a schematic for an ignition coil requiring a capacitor; my hope is that it is correct. Thoughts please?

swap the capacitor out for a ballast resistor, will do what you want.

Edit.. unless you mean you want a suppression capacitor for points bounce, but the dizzy should already have a capacitor in it, if not it goes from -ve coil wire to earth, mount as close to dizzy as possible.

What you have drawn is a diagram suited for a ballast resistor setup using relay, to give full volts to coil when cranking and reduce volts when running, you can do it without the relay too.

Also you can buy a coil that sucks less running current but still gives high spark voltage and none of this wiring needed.

try this...

30 to IGN+ (always hot if ign or cranking)
85 to start signal
86 to earth
87 to coil positive
across pins 87-87a wire a resistor with between .8 and 1.4 ohms (lots of vairables here) rated for a constant 10-15w.



heres a sample.


universal Ignition Ballast resistor for use with 1.6 Ohm Ballast coils | eBay

Originally Posted by Blknight.aus

try this...

30 to IGN+ (always hot if ign or cranking)
85 to start signal
86 to earth
87 to coil positive
across pins 87-87a wire a resistor with between .8 and 1.4 ohms (lots of vairables here) rated for a constant 10-15w.



heres a sample.


universal Ignition Ballast resistor for use with 1.6 Ohm Ballast coils | eBay

I appreciate everyone helping, Is what I need and why i asked. This section or your post is hard to get my head around.{across pins 87-87a wire a resistor with between .8 and 1.4 ohms (lots of vairables here) rated for a constant 10-15w.}

I edited the post and will again until it is correct [I hope].