The Blue,the Black and the Ugly (White)

[duivendyk]

You might be able to do a gross dissection of what I take to be deceased CDI unit,that is to identify major organs,like the output pulse transformer,that's the thing that steps up the voltage coming out of the energy storage capacitor and connects to the plug cable, and the storage cap. itself ,probably a good sized round affair with a lead sticking out of it at each end.But you would have a hard time with the nervous system,wiring,IC's etc.
Frankly I'm kind of leery of the whole thing, not even sure it is a honest to goodness real life CDI!,it's probably not worth while shipping the corpse half way across the planet for my expert scrutiny.My aim is to come up with a HT charging system that people with your sort of background can put together with readily available parts and which of course works well.I have been to Aussiland,but only NSW & Queensland,skipped the Ayers rock, a real tourist magnet.Nice cities, impressive scenery,nice people and very good beer.My brother in law lives near Brisbane.

 

[Drunkskunk]

I'm thinking this may not be as complicated as it's being made out to be.
A diode inline with a resistor from the white wire to the battery should provide some measure of charging. Using a zener diode in parallel should protect the battery from overcharging.

Most likely, the CDI would discharge when the voltage goes low in the AC pulse, instead of going all the way negative. With that being the probable case, the white wire could be used with no fear of disrupting the ignition, as long as it didn't draw too much current.

 

[arceeguy]

You might be able to do a gross dissection of what I take to be deceased CDI unit,that is to identify major organs,like the output pulse transformer,that's the thing that steps up the voltage coming out of the energy storage capacitor and connects to the plug cable, and the storage cap. itself ,probably a good sized round affair with a lead sticking out of it at each end.But you would have a hard time with the nervous system,wiring,IC's etc.
Frankly I'm kind of leery of the whole thing, not even sure it is a honest to goodness real life CDI!,it's probably not worth while shipping the corpse half way across the planet for my expert scrutiny.My aim is to come up with a HT charging system that people with your sort of background can put together with readily available parts and which of course works well.I have been to Aussiland,but only NSW & Queensland,skipped the Ayers rock, a real tourist magnet.Nice cities, impressive scenery,nice people and very good beer.My brother in law lives near Brisbane.

A CDI doesn't have to have any Integrated Circuit Chips. Just a diode, capacitor and an SCR that will trigger on the falling edge waveform of the magneto. A 5 wire pocket bike CDI with automatic spark advance would be nice if you could rig the pickup sensor and trigger magnet on a HT engine. (This means a separate CDI and coil though) I think the CDI on these units are probably very simple with no spark advance built in. I'll have to get a scope on the outputs once I get my Moon Dog barking!

 

[duivendyk]

Yeah,differentiating the negative going portion of the input wave form to derive a trigger pulse for the SCR could do it and provide automatic spark advance as well.I was thinking of using a Zener+ LED(as indicator)to start cutting off a normally saturated series pass transistor (or MosFet) when the battery voltage gets above above 7V.You would lose about 0.3 to 1V with that depending on what device is used.
It would be very useful to get some idea what the peak to average ratio of the white wire signal is,I bet it's quite high.I have a peak reading Fluke but it just takes any old diode,a 10k resistor or higher and a cap across it with an RC time constant above 100 msec ( 100k with 0.1 micro farads).There is bound to be a lot of EMI electrical trash around.The rectifier could be just a single diode,or a full wave Schottky diode affair.But that gets you into some complications,either you have to float the ignition circuit in order to be able to have one side of the battery grounded, or the battery circuit itself has to effectively have the white wire ac on it.The first option looks to me like by far the lesser evil.

 

[BoltsMissing]

http://www.eindiancompanies.com/cdi/digital/index.htm

No longer in production, but has been done, programmable CDI.

 

[BoltsMissing]

Disection Of HT CDI, during lunch break

It was "war" !

 

[arceeguy]

Looks like it is about as much fun as removing a fossil from granite!

 

[BoltsMissing]

Going by the softness of the Copper wire, it became obvious that it don't take much to burn them out.
The wire felt soft like paint brush hair.

 

[relaxxx]

From image 12, looks like nothing more than a stepup transformer inside.

 

[BoltsMissing]

From image 12, looks like nothing more than a stepup transformer inside.

Yes, similar principles weather it was a battery charger, electric train set variable transformer, whatever, coils of wire wound around a bar.

The point is, the actual composition of the Copper wire.
Convincing the fact further to use On/Off switch rather the the standard HT kill switch, in my humble opinion.