This circuit turns an AC-CDI into a DC-CDI.

An AC-CDI needs a working STATOR to charge. If the stator fails, let it be rewind or buy a new one is pretty expensive!
This circuit was designed to bypass the faulty stator by making High Voltage (around 100 to 200V) directly from the +12v battery.

When the internal SCR of the AC-CDI has been latched in ON state for a spark, only the voltage crossing a falling zero will turn it OFF again. In order to let the SCR return to blocking state, this circuit alternates ON and OFF states.

  • 50 to 20,000 RPM
  • Kill switch
  • Power supply voltage DC 12 volts
  • Current drain: 60mA to 1.3A
  • 2A Fuse Protection
  • Dimensions: 75 x 50 x 25mm (3 x 2 x 1 inch)
  • Available in the SHOP section


FRQ solder pad:
If open (default): Frequency of the circuit is 1000Hz (equal to 6 pulses/rotation at 10000RPM)
If close: Frequency of the circuit is 500Hz (equal to 3 pulses/rotation at 10000RPM)

PWM solder pad:
If open(default): HV generator alternate ON/OFF period at 50%
If close: HV generator is 100% ON, no OFF period. /!\ This can lead to the destruction of the internal SCR of the CDI. Try this at your own risk!

Kill switch:
Remove the KILL wire from the ACCDI and connect the Kill Switch to this Power module
If Kill input is connected to Ground: DC generator stops and Led turns ON.

Over Voltage Protection: Turn the trimmer to adjust the maximum voltage.
+180v at position N°1
+90v at position N°5
Led turns ON when OVP is active.

Transistors need a heatsink if run at 15000rpm longer then 1 minute.

Blue: Mosfet Gate. Yellow: DC output


Click here for more info




  • Version V1R2C1:
    • First Version.
  • Version V2R0C0:
    • [soft] Improvements.

3 thoughts on “AC-CDI 2 DC-CDI”

  1. Hi Thierry
    Sorry to write you again but I just saw that you are doing something similar to what I asked you in the previous email AC CDI 2DC CDI and I see that you do not have it for sale yet but you could send me the program and the PCB to go doing tests.
    Thanks Jose Luis

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