FinnBoxG47 (FBG47) AC-CDI Unit
"If you can't buy it, you can make it!"
More detailed description of my FBG47 ac-cdi unit is here.
My FBG47 unit is a direct replacement for the original Honda CX500 ac-cdi unit. It means that the pick-up coils, advance pulsers and the stator namely G47 have to be in good working condition. I think an ac-cdi unit's benefit is that you can push-start cx if the battery is empty. You can ride without lights back to home. It is also robust consisting only a few active components while the rest are passive ones. No mirco-controller inside. Old fashion way but to be old fashion does not mean to be restricted! FBG47 produce the same way as the old unit a linear, rising advance curve from 2000 rpm up to about 6000 rpm. The curve is stepless totally. Dare to say it's more than enough for Honda CX500. The biggest improvement is that FBG47 has all the new and up-to-date components. Nowadays components quality is improved in 30 years quite a much. There is not anything special or mysterious things in my circuit. All the components and electronic solutions are well known. The question is only how to determine the components in correct order to produce desired function..
The empty circuit boards are manufactured according to my drawing at a local electronic company. The trace side copper surface is totally tinned to prevent oxidation. The component holes are drilled with a CNC machine. I have soldered all the components and installed to an enclosure to keep the total costs low enough. Enclosures are ABS plastic with 3 mm wall thickness. Cover is sealed with an o-ring.
Here's the correct and proper installation of FBG47 ac-cdi unit. Photo by Eric Smyder.
I installed FBG47 to an aluminum enclosure to see would it be any better. There is also a slot in the cover part for future pcb use. Overall size is little bit smaller than ABS plastic box but the height is 35 mm instead of 30 mm. It fits under the seat just fine.
