[QUOTE][Pre transistor ignition could have switched 12V instead of 25kV, and used individual step-up coils to transform 12V to 25kV at each spark plug as they do now. Would have saved a lot of grief./QUOTE]
ERRM....but that's exactly what they DID do! Primary of coil was energised via points....created strong magnetic flux in coil....points opened, flux colapsed, aided by condenser which also damped arc-over at points....collapse induced high voltage in secondary......now the clever bit
the same shaft was utilised to drive the rotor-arm which merely guided the HT to the appropriate "stud" in the cap which was assigned to the correct cylinder........the cap served more than one purpose It held the HT leads in alignment to catch the HT pulse, kept damp and dirt out and insulated the HT leads from each other and "earth"
Some very early engines had 2 wires in the cylinder-one was cranked to touch the other and mechanically swivelled to form a spark-gap,as it was fed , initially, with battery-voltage (usually very low...6V was standard-practice before WW2 and early 50's saw standardisation of Negative-Ground and 12 volts.
Let's not forget the "Trembler-Coil"..basically an electric-doorbell without the gong and hammer!
When the speed of V-8's made timing marginal and sparks weaker, Prince of Darkness used 2 sets of points in series, thus almost doubling the available Dwell-time....a kludge but it worked reasonably well.
they developed electronic ignition in the late 70's Rolls Shadows and Spirits had a potted board with 4 transistors, in the Distributor body..a n inductive pickup was aligned to an 8-finned sleeve on the central shaft..as a fin passed the pickup it disrupted the current-flow...amplified and used to switch the coil primary....a conventional cap and rotor distributed the spark-current to the appropriate cylinder.
I think Jaguar , triumph stag, Rover/range Rover all used the same system.
After~20 years, the low-signal transistors became unreliable...car wouldn't start or would cut-out , only to restart after a 5-minute rest and often perform faultlessly for days ,before playing-up again.
The transistors used were at the bleeding edge, in their day....modern replacements ~5p each give instant starting and reliable running...
Give the Prince his due, late to the table, but produced the goods when he got there.
Unlike the modern system, one cylinder misfiring didn't bring everything to a grinding halt
Magnetos were used on early aircraft....still used today...100 years of proven ,reliable technology at work
