Capacitance Discharge Ignition System

[jaap de vries]

Dear friends,

I am building a CDI system to ignite fuel mixtures in a pressure chamber for flame speed measurements.
I need a capacitor of about 5 nF, but it should hold up to 10 kV.
Any suggestions on where I can get those. I also need a diode (rectifier) for 10 kV. Also I need high voltage relays.



Jaap

 

[NoTime]

Ummmm.
Where are you getting you component values from?

Normal CDI, the spark coil generates the HV (10Kv to 30Kv).
With a standard spark coil 100v to 350v on C of 1uf should give about that output range.
So your diodes and relays only have to rated for about 600v.

 

[ravenprp]

,

Thank you for sharing your project with us. Building a CDI system for flame speed measurements sounds like an interesting and challenging project. To answer your question, there are a few options for obtaining a 5 nF capacitor that can withstand 10 kV. One option is to purchase a high voltage ceramic capacitor from a supplier like Digi-Key or Mouser Electronics. These types of capacitors are specifically designed to withstand high voltages and can come in various capacitance values.

Another option is to use several smaller capacitors in series to achieve the desired capacitance and voltage rating. For example, you could use five 1 nF capacitors in series to achieve 5 nF with a voltage rating of 10 kV. Just make sure to properly calculate the total capacitance and voltage rating when using multiple capacitors in series.

For the diode, you can also purchase a high voltage rectifier from a supplier like Digi-Key or Mouser Electronics. Just make sure to select a diode with a voltage rating of at least 10 kV.

As for high voltage relays, I would recommend consulting with a specialist or engineer who has experience with high voltage systems. They can help you select the appropriate relay for your specific needs and ensure it can handle the high voltage requirements of your CDI system.

Best of luck with your project and please keep us updated on your progress!