How does an ingnition box work

[d72hemi]

Like i tell the guys at work, "I am allowed one stupid question a day".

What exactly does an ignition box do, and how does it do it? I understand that Voltage goes to the coil, bumping up the Voltage to just the plug gap. Then it is sent to the distributer, which sends the voltage to the proper plug, then BANG, we have combustion. How does the igition box fit into all of this? Also how does an MSD box differ from a standard box? If anyonehas digrams that would be awsome, I work on elecrtonics for a living, so digrams would help me understand a lot. 

Ian

[Chryco Psycho]

the ign control box is really just a switch when it sees the voltage spike from the dist it opens the switch for the coil ground collapsing the feild in the coil & creeating a spark as soon as it does that it regrounds the coil to build a charge for the next spark

[John_Kunkel]

The MSD (Multiple Spark Discharge) box fires the plug multiple times at each event rather than once like the stock box does. The number of sparks is higher at low speed and dies off to a single spark at high rpms.

[d72hemi]

A MSD box just interups the ground multiple times? basicly flipping a switch on-and-off (really fast) durring the time that the rotor is sending Voltage through the cap to the spark plug? Does the Ignition box, ground the coil (really a transformer), before or after the rotor makes contact the cap? Also, is the Ignition box grounding the primary coil (from the Alt/Battery) cusing tihe field to collaps on the secondary coil, which is now grounded by the spark plug through the rotor and cap? What voltage is the Ignition box "looking for" from the dist.? I just want to make sure that I am on the right page. Does any one have circuit digram? for either box? I have a lot of time and a bunch of electronic parts to cannableize at work. I would like to make my own box, just for the hell of it.   

[Chryco Psycho]

MSd will fire twice up to 3000 rpm , above that it doesn`t have time to fire more than once just like the stock ign sytstems 
the coil is grounded btween the terminals on the cap , as the rotor approaches the terminal the ground is broken collapsing the primary circuit & building high voltage in the secondary coil circuit which as you stated basically grounds across the spark plug
the dist creates a pulse in millivolts that is sent to the ECU