This page is for ongoing development of the best IonSense circuit (assemblyoptions) to continue the development of functional circuits that allow high energy sparks while also permitting effective protection and accurate measurement of Ion Currents. Of course it would also be nice to list formuals and links here too.

We should dicuss circuit aproches and possibly do some simulations (provided we find people int to it and the spiceFiles to support the components to be simulated...

I posted the ltspice files a long time ago in the files it has both spice files for the car coil and and a sparkplug.

also some cool dc-dc for the powersupply too

the powersupply is I think

I will need to go look at this it has been a long time.

I think the sparkplug and coil is in the patch tar

winzip seems to not untar the file. you need to save the file patch.t and rename it to patch.tar and run winzip on that. has some spark theory and a downloadable Spark Plug Spice Model!

I found some very interesting looking Simulation Software! [First I found this presentation]

[Then I found they have a free full featured but limited in the size of problems that can be solved student version] I installed it and its nice indeed! - Togo

Togo: As I remember from experimenting with High Voltage - one does really need AC HV to get a nice and Fat Plasma Spark maybe the PWM Ignition is already implemented?

Challenge is to introduce the Ionization Voltage and decouple the precision ADC Data acquisition! Maybe You have some new ideas ?

There are other pages to know about:

IonSense/Components We need to know what is out there often it comes with spiceFiles

IonSense/HardwareDesign This is where we publish circuit versions and ongoing PCB work

CoilOnPlug How many windings, diodes, coreoptions etc On this page we have an apparently quite proffesional sample Scheme. Thanks to Adrenalineresearch!

Togo: Ok here is my Suggestion:


Note: this is just an initial drawing obviously incomplete and the components are not selected and do not claim to survive their conditions etc. Of course here is the place to suggest what to improve, what particular components would be best and so on:

Togo: Comment: My circuit is based on the assumption that the Ignition Transformer gets 'quiet' quick enough and has a low enough impedance on DC to measure the current over its secondary. Further I am assuming that the 400V Charge accumulator C1 can sustain its ~400V given the Ion Current for long enough to get to the next cycle. It will be recharged during the Exhaust cycle and even the Spark Phase. Only the right part is duplicated for each cylinder. I like that it doesn?t require those scary 50 diode chains, also the diode design limits us to effectively only DC Spark energy... And as I remember from playing with HV DC discharges are rather lean and cold in comparison to AC! Theoretically it even becomes possible to measure the spark current! Of course that is in a whole different current range of its own (any ideas how much in mA?).

Togo: To calculate the required capacitance of C1, I would like to know what kind of ion current range can we expect?

Also to consider the potential to use the capacitor and the 400 Volt towards the end of the discharge and calculate the spark energy remains the question at which voltage would the spark extinguish itself?

Smart design, only downside as I see it is that the charging must be controlled and that the ION voltage may need to be monitored during the discharge as well. The current mirror design below (only the stuff on to the right is related to ION, the rest is CDI and Plasma discharge) will happily take ION readings continously with only a 100-400v DC supply. -J├Ârgen

Schematic removed to avoid confusion, GND and a signal was accidently connected. New one will be added ASAP

Note that the Diode D3 is built into the coils that we will probably make our standard. JP1 is there to visualize the primary-secondary connection in coils not prepared for ION. But as I see it the ION prepared BERU coils used in great numbers on BMW, VW and Audis is the best standard coil we can get.