New Ignition Project Finished

[Bob_W]

I have built a 1/2 scale Olds engine to the point of getting it ready for the finish work. It is now running fine and will need the detail work completed before painting. As slow as I have been going lately, that will take as long as it took to build the engine.

I had been prototyping several different types of ignition systems for a while. I have built two versions of a PIC microcontroller ignition with multiple spark capabilities, buzzcoil ignition and finally decided on the CD ignition shown in the picture. Not exactly 'scale', since they probably weren't considering electronic ignition in 1900's but I wanted to do something different. This one has the advantage of being able to run 14 - 18 hours on a single 9 volt battery (don't need to carry a 12v battery around!) and will not draw additional current or burn up a coil if the engine stops with the points closed. The coil in the picture is from a Johnson outboard motor that I had available but the ignition has worked with auto coils and also the small Modelectric coils.

I had considered making kits but not sure I want to get into that yet. I just have fun building and playing with these things. Does this seem like it may be of interest to anyone on the board? I don't see why it wouldn't work on full size hit and miss engines either. I will post a picture of the engine in the following post.

What other ignition systems have you guys been using (other than standard points)?

Bob

[Bob_W]

This is the picture of the 1/2 scale Olds engine. As you can see, I still have a lot of finish work before painting. I haven't even started to build the cart yet! Oh well, that may be the late Fall project. It runs very well. It will slow to the point of barely having enough energy to pass through the compression stroke. It then has only one chance to 'hit'.

Since I have had problems with the gasoline slowly attacking the paint on other engines I have built I had considered a clear Polyurethane top coat. Has anyone done this? We have use the urethane paints on some gas powered model airplanes and it seemed to work OK so I was thinking it might be OK on these. Any thoughts?

Bob

[Doug_C]

Nice work Bob,

Any paint that is not epoxy or 2 part will have a solvent base. That makes them disolve when expose to fuels too.

I see in your ignition circuit a transformer is used. That steps up the voltage to the primary of the coil to what?

DC

[wayne_olson10]

Can post your source for the ignition ckt or post a ckt diagram some how, Great Job and nice work._wayne

[Bob_W]

The circuit has an oscillator that drives the primary of the step up transformer (ordinarily would be the secondary) such that the output generates 400+ Vdc after a voltage doubler. That dumps to coil when triggered.

Bob