Trenbler Coil--(Constant spark)

[Brian Rupnow]

I am interested in trembler coils, similar to that used in Model T fords. In a conventional points style ignition, you get one spark at the plug when the points open. With a trembler coil system, you get a series of sparks whenever the points are closed. There are a ton of "How to" articles on building your own trembler coil on Youtube, and it seems that I already have most of the components (a 12 volt coil and a condenser.) It seems that all I need to buy is a special relay, which is commercially available. Does anyone have more information pro or con about these trembler coil systems?---Brian

[Jasonb]

You can also buy reproduction parts just like the old Model Tee ones rather than use a relay, just add an ATV coil and condenser and off you go.

https://flywheel-supply.com/kw-buzz-coil-points/





<a href="https://www.youtube.com/watch?v=mtte8UXowUo" target="_blank">http://www.youtube.com/watch?v=mtte8UXowUo</a>

[Brian Rupnow]

Thanks Jason--I went down street today and bought a 5 pin relay at an automotive supply store for less than $10. That, along with the stuff I already have should yield what I need. I will post a video.--Brian

[Brian Rupnow]

Going boldly where I've never been before---If a trembler coil system produces sparks only when the points are closed and the current is allowed to flow---then you need a cam that is  reversed from what a conventional cam is like on a conventional ignition system. You would want the cam to hold the points open most of the time, and only allow the points to close momentarily when you want it to fire.  So---This is my shot at a reverse cam lobe.

[Jasonb]

It really depends on how the contacts are constructed as to whether you need a different cam profile as pressure on the point scan either open or close them. Just depends if it is press to make or press to break.

Come to that you don't even need a cam like traditional points tend to use, just a rotating contact and a second fixed contact that will spark for as long as the two are touching. This is what the majority of hit and miss engines use.

[Brian Rupnow]

This morning I am down in my shop wiring up a trembler coil, based on a wiring diagram I found on the internet. It uses a standard 12 volt automotive coil and a five pin relay, along with a condenser and an on/off switch. I'm happy with my results, and will be trying this ignition system out on the model i.c. engine I have recently built.

<a href="https://www.youtube.com/watch?v=22kARkE0CXI" target="_blank">http://www.youtube.com/watch?v=22kARkE0CXI</a>

[crueby]

Very interesting!  Hope it works out on the engine too!

[Brian Rupnow]

Today I'm learning all about trembler coils. Perhaps more than I ever wanted to know!! I have everything hooked up, electric starter, engine, and trembler coil. The trembler coil fires the sparkplug like crazy ---but only when the engine first begins to rotate, or when the engine is coasting to a stop. However, it doesn't want to fire the sparkplug while the engine is turning at a higher rpm. Okay, that's weird!!! My best guess is that this failure to perform at higher rpm has something to do with the amount of flat that I have on the cam. Damn!! I thought this was going to be easy. This coil fires when the points first MAKE contact, opposite to a conventional points and coil system which fires the coil when the points BREAK contact. Right now, the cam has a flat on one side only, as shown in the attached model. MAYBE I have to make the flat area on the cam extend part way around the 360 degree body of the cam so the system has a longer "dwell" with the points in contact with each other.

[Brian Rupnow]

Maybe the cam should look like this, so that the points stay in contact a much longer time. This would agree with what George Britnel is saying, that the ignition cam should almost look like a valve cam. I'm kinda lost in the woods here.---Brian

[Jasonb]

It partly depends on if the points are being pushed shut or pushed open

That profile will likely give far too long a spark and you will run the battery down and get a hot coil, If you want a bit more spark duration then you need a profile more like this which would give a spark for 45deg of cam rotation therefore 22.5deg of crank rotation which should be more than enough

[Brian Rupnow]

Time now to put this thread to bed. I did build a trembler coil using a standard 12 volt coil, a condenser, and a 5 pin relay. It worked like a charm, with a marvelous series of sparks. I ended up not using it, but it worked, and worked very well. Not everything I build works out successfully, but this did work as advertised, and I was very pleased with the end result.---Brian