I need a schematic of a circuit to convert 12vdc into 6vdc

Hi, I need a circuit to convert 12vdc at 15amps into 6vdc at 12-15amps. the reason I need the circuit is I went to a yard sale the other day, the lady's husband (who had worked on engines) had passed away and she was selling a lot of NOS engine parts... I found a brand new ignition coil still in the box that was marked $.50us so I bought it for my lawn mower engine that had mechanical points but the PO had installed an electronic maginito onto the engine and now the maginito is failing. Well when I got home I noticed the coil said it was for a 6 volt system and the original system was 12 volts and I can't get a 6 volt starter for a 1977 8hp briggs and stratton engine. so I need a circuit to make 12vdc into 6vdc for the ignition coil but keep the rest of the system at 12vdc and have a common 12vdc negitive ground.

thanks in advance,
John

maybe wire a zener regulator in parallel with the coil?

With any linear regulation method you are going to loose 1/2 the amps dropping from 12V to 6V.

Check to see if you can get a switching regulator, but there will still be some loss.
Mouser and Digikey have pages of them.

EDIT: Somehow I did not read all of the original post. A switching regulator may cost too much.

Might try about .3 ohms in series with the coil. Maybe 3, 1 ohm 10 watt in //.

might sound kinda dumb but why not just use a motorcycle battery 6v for the ignition and 12 v for the starter.
then just wire up the charging system to charge the 6v and 12 v batteries.

Or just buy or scrounge a 12V coil. Using the 6V coil is just too much work.

I did not know how much current a coil draws. But I am thinking 12Amps is a lot for a 1 or 2 cylinder engine. Where did you get that number ?

That sounds like really a lot of current. I think gas is a bit more flammable then that.
this site talks about using a 6v coil with a ballast.
12v Or 6v Ignition Coil?

thanks "EternityForest" and everyone else, I now have the info I need