CDI Capacitor Discharge Ignition Circuit Demo

this is a simplified drawing of a CDI capacitor discharge ignition all the way to the left is the exciter coil and it has a rotating magnet that induces an AC voltage in that coil below that is the pulse rotor it has one magnet and it induces a voltage in the trigger coil now the rotation of these will depend on the requirements of the motor and I chose a rotation pattern strictly for demonstration purposes up in a little bit to the right is the ignition stop switch when that's closed it basically shorts out the voltage that would charge the capacitor to the right of that is the diode d1 that diode is the one that lets the voltage through that charges the capacitor to the right and between those two is the SCR that is a solid-state device that triggers the discharge of the capacitor which then produces a spark and that happens when the gate gets a signal from the trigger to the right of the capacitor is the ignition coil and spark plug now the magnets have rotated and has induced a voltage and the exciter coil with this polarity negative on the bottom positive on the top and when that happens d1 will conduct and here you can see the charge path for the capacitor when the magnet continues to rotate we don't have any current but notice that the capacitor is still charged and when the magnet is in this configuration we've got the opposite polarity and still nothing happens because the diode will only conduct in one direction and as we continue and get to another South Pole we have the polarity again negative on the bottom and positive on the top and d1 conducts and we get a little more voltage in the capacitor and again we don't have anything until we get to another South Pole and we have a little bit more voltage put into that capacitor and now we're coming up on another South Pole and now the capacitor is charged completely now take a look at the pulse rotor in this position it is induced a signal into the trigger which goes up through the resistor onto the gate of that SCR that SCR now fires our shorts out and all the voltage that was stored in that capacitor now discharged and produces a spark at the spark plug now the capacitor has started charging again and the voltage and current that is going through the primary of that ignition coil is low enough that it will not produce a spark but it is enough to start charging the capacitor I'm going to let this run for a while so you can see the sequence a few times you thanks for watching

Channel: AllAmericanFiveRadio

Views: 755,367

Keywords: CDI Capacitor Discharge Ignition Circuit Demo, Capacitor Discharge Ignition Circui

Id: 0yK3Opq_i0M

Length: 5min 31sec (331 seconds)

Published: Thu Sep 12 2013