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Last Updated: September 06, 2013

Shogun DC-CDI schematic

The picture shows an OEM dc-cdi of a Suzuki shogun 125cc that prior on my recent posting about kawasaki OEM dc-cdi, they are almost identical, parts used are almost exactly the same although in a different layout and or placement on the PCB. However, i recently found out the two dc-cdi differs on the design of their HV generator.

Digital DC-CDI by the way uses microprocessor on the pulse shaping circuit to maintain integrity and reliability of giving out right timing all the time when the spark plug will fire the combustible material inside the combustion, it is also to where the ignition map of the engine is stored for accurate timing. Many OEM uses MCU specific for their design and no available datasheet for us to understand it fully. This OEM upon analyzing the entire board has an Rx, Tx, and ground port, and if only i have the datasheet of the IC, perhaps we can be able to extract the data and dump it to a computer for further enhancement.

Again about the High Voltage design of the said DC-cdi's, although both uses forward converter topology, a design for simplicity  and low cost, but according to some articles i had always been reading, the design lacks efficiency at higher rpm and cannot cope more on charging the capacitor, thus limited power at top end.

The building block of this dc-cdi are

1. the pulse shaper circuit
2. TPS
3. MCU
4. SCR and oscillator trigger
5. HV generator

I had made and sketch each and every block with the exception of the MCU and related part for it to work, this article will only cope the four other block.

Pulse shaper circuit

Pulse Signal Amplifying circuit

TPS circuit

SCR and HV oscillator trigger

High Voltage DC-DC converter circuit

Looking at the High voltage converter circuit, it is almost identical with the one posted on the Dc-CDI schematic . Any CDI made to be DC needs an ON-OFF circuit that will stop the oscillator of the converter to ensure safe discharge on the capacitor and avoiding SCR lock during discharge.

The power of the dc-dc converter determines the capability of the CD ignition to rev higher, that when it cannot cope for the time it can charge the capacitor at higher rpm, then the overall power of the engine will be limited.


If you know how to read the schematic diagram..there is a room for improvement on this DC-CDI to rev past 10,000 rpm...or give a higher output voltage that will feed thru your ignition coil.

Remember that in one of my article about CDI at this site, the CAPACITOR and the HV converter section plays an important role on any DC-CDI design...the pulse shaping on this OEM cdi is digital so whatever it sense it will still try to give you the right timing of spark, irregardless of advancing or retarding your pulser coil.

CAPACITOR VALUE is critical..lower the value and you'll have a low energy of ignition but you have to compensate the HV output by raising your secondary output of the transformer. HOW? find it out.