Fairbanks-Morse hit and miss

[MarkySparky]

I have a natural gas hit and miss engine on my gas / oil well. It is a Fairbanks Morse 208 Hit n Miss Natural gas engine 1943. 12 hp 6" single cylinder. 650lbs.

It has a magneto and a CDI system. When the CDI dies it costs $500 USD to replace the thing. It’s a potted black cube that I refuse to believe is that expensive. There is a bank of three charging magnets on one fly wheel and a set of two trigger magnets on the other flywheel.

I’m trying to recreate this circuit and need some help. It would be awesome if the circuit I make can run off the magneto but I also want to make a version that runs off of 12VDC - I have a solar panel and truck battery out at the well to power a starter I made for the engine.

Anyone ever make their own CDI and can you help?

Kindly,

Mark Hamilton

 

[MarkySparky]

I have a natural gas hit and miss engine on my gas / oil well. It is a Fairbanks Morse 208 Hit n Miss Natural gas engine 1943. 12 hp 6" single cylinder. 650lbs.

It has a magneto and a CDI system. When the CDI dies it costs $500 USD to replace the thing. It’s a potted black cube that I refuse to believe is that expensive. There is a bank of three charging magnets on one fly wheel and a set of two trigger magnets on the other flywheel.

I’m trying to recreate this circuit and need some help. It would be awesome if the circuit I make can run off the magneto but I also want to make a version that runs off of 12VDC - I have a solar panel and truck battery out at the well to power a starter I made for the engine.

Anyone ever make their own CDI and can you help?

Kindly,

Mark Hamilton

Update: I have a working prototype now and I’m going to install it today.

 

[stevehuckss396]

Did you use some of the cdi designs from ideas presented on the forum or is it a new design that you created fresh. Pictures would be awesome.

 

[MarkySparky]

Update: I have a working prototype now and I’m going to install it today.

You just caught me before I went out the door… I got some good starting points and historical wisdom from Roy and then I spent a lot of time in circuit books and in the lab futzing around reverse engineering and then testing and then more testing and then I sent off to China to have a couple circuit boards prototyped.

I suspect that I might not have a very hot spark in terms of what I’ve seen others produce, but I bet it will work.

I’d love to get those sparks that can shoot 1/2” but for now this will work and it is repairable

 

[MarkySparky]

You just caught me before I went out the door… I got some good starting points and historical wisdom from Roy and then I spent a lot of time in circuit books and in the lab futzing around reverse engineering and then testing and then more testing and then I sent off to China to have a couple circuit boards prototyped.

I suspect that I might not have a very hot spark in terms of what I’ve seen others produce, but I bet it will work.

I’d love to get those sparks that can shoot 1/2” but for now this will work and it is repairable

 

[MarkySparky]

Does anyone know of anyone that has made a scaled down version (working model) of a Fairbanks-Morse 208, 12HP?

Or maybe a virtual model in 3D?

 

[MarkySparky]

Ok here is the update from testing

I blew up two power supplies.

Aobao 2pcs High Voltage DC-DC Boost Converter 8V-32V to 45V-390V ZVS Step-up Booster Module Capacitor Charging Power Supply Module Adjustable Voltage Output https://a.co/d/fIrpS1i

I really like these circuits but I goofed up. I tested my CDI using a plug in 120-12vDC, 0.1A wall wart. When I connected the circuit to two 12 Vdc truck batteries I didn’t have a way to current limit the giant source.

So I faked it… I used an inverter to make 120VAC from the truck batteries then plugged in my wall wart. The engine worked great.

There has to be a better way to limit my current and maintain 12VDC input.

Good news - when I did the inverter trick, the engine ran.

 

[byawor]

here is pic of 1/4 scale Fairbanks not sure if same as yours

 

[byawor]

here is pic of 1/4 scale Fairbanks not sure if same as yours