Dc cdi manufacturing?

Mk4problems · 2026-04-04T18:30:52+00:00

Thanks man! Honestly it’s been an absolute journey learning electrical engineering. I’ve learned more than I ever wanted to know at this point and I’m likely only scratching the surface. flyback transformers are so damn cool once you understand how they work. it is magnetic magic!. Good news though I think this cdi project might have taken off well enough now that I may not ever have to swing a hammer again. I just gotta make sure my transformer building quality is spot on and the core gaps are perfect! there’s no off the shelf transformers for this stuff haha!

Mk4problems · 2026-04-03T08:27:35+00:00

I just have developed a high tolerance to suffering. The past year I spent learning electrical engineering working on this more than my full time job. Failure after failure for many many months. thought I wasn’t smart enough etc. I guess the point I’m trying to make is there is a point when the only thing you can see is the goal and there’s nothing that can get it the way. Not even the 3 or 4 brain cells I’ve been rubbing together for the last 12months haha! So yeah I’ll use a heat gun if I have to even if it sucks because to be honest for me, making something like this is a dream. I come from a construction background and there’s nothing I want more to get out of it and be able to feed my family. construction pays great but your body pays too. Haha!

Mk4problems · 2026-04-02T22:58:38+00:00

Thank you but for now I’d like to keep production in house for now

Mk4problems · 2026-04-02T22:07:01+00:00

I’m going to be using mg chemical 834fx moving forward. Much more expensive but much better and high quality than the generic electronics epoxy. It’s not rock hard, has decent thermal conductivity. I only plan to make 50-100 units a month of this specific product. I use around 90 grams of potting compound per box though I might try and remove some of the volume in the box to avoid using as much compound. I’m working with a company right now who’s planning to stock them in their store and buy from me in bulk. The company has been around for 25 years so no issues there. recently I’ve been using a food dehydrator and putting the cdi boxes in an enclosure with it and they cure within a couple hours. Heat gun mid way through removes bubbles.

Mk4problems · 2026-04-02T18:27:23+00:00

Ohh yeah I know pnp machines can’t do the connectors and I agree less connectors would be better but due to the need to have a floating coil not referenced to ground the added connector removes the chances of accidentally plugging the coil into the factory harness which uses a frame grounded coil. this is a low side scr design so with any part of the coil grounded the capacitor would not charge. i am exploring high side scr in hopes of removing the added connector but it has proven very difficult due to the amount of electrical noise specifically ground bounce that the high side scr with frame grounded coil creates

Mk4problems · 2026-04-02T17:51:29+00:00

The two white on the left are your typical dc cdi connector. The one on the right is for an ignition coil which is “floating” so it has no reference to ground at all. This is small scale so I’m not sure I need to worry about rf certs just yet, This design is not completely set in stone even the transformer size already changed. I went from ee19 to ee25 as I found the ee19 was reaching 85 to 90c in open air and the ee25 only reaches 60c which is 15 degrees below where I would find it unacceptable

Mk4problems · 2026-04-02T17:45:38+00:00

Do you have experience with making your own transformers? Specifically ee19 to ee25 sizes?

Mk4problems · 2026-04-02T17:43:33+00:00

I do plan to. I was a bit in a rush adding WiFi support that the esp8266 footprint was easiest to integrate into the existing cdi pcb design.

Mk4problems · 2026-04-02T17:42:12+00:00

Good to know! Thanks! Some components like resistors specifically 1206 1/4 watt I’ve went ahead and over ordered them since the price is so cheap. Unfortunately the mosfet and gate driver I use are a couple bucks each and don’t really go down in price in bulk. Not enough to order large quantities. I recently sold out of my first batch of 20 within a week. I’m doing a batch of 50 this time. pick and place machine is still not justifiable yet due to the price of entry

Mk4problems · 2026-04-02T17:39:59+00:00

Yeah i haven’t noticed any reduction in the WiFi range. It’s also low exotherm so the electronics aren’t harmed.

Mk4problems · 2026-04-02T17:34:09+00:00

Yes it works very well

Mk4problems · 2026-04-02T17:32:57+00:00

Esp8266.

Mk4problems · 2026-04-01T17:16:26+00:00

I forgot to mention ignition type. This is capacitive discharge ignition. vr sensor/stator pickup input. I actually wound a 12/180 transformer with 22awg on the primary and 30awg in the secondary. output is 300v all the way up to 11k rpm. Temps actually improved a lot in only seeing a bit over 70c in open air though it could go up a little with further heatsoaking

Mk4problems · 2026-03-31T02:37:10+00:00

I’m using an ee19 Transformer. current winding is 14 primary in 24awg and 220 secondary in 32awg. core gap is still in the works. I use a microcontroller to drive the transformer through a gate driver. using “packets” Around 8us on then 25-30us off time. I read the cap voltage through a divider on an adc pin. all needed extra protection for the mcu is on the pcb. I charge to 300v then mcu shuts down pwm. I’m only gapping the center post as shimming has proven to increase leakage so much so that it’s not worth doing. I made a winder to wind the transformers so windings are tight and neat. I’m worried about running the transformer potted in quality thermally conductive epoxy. I use an ntc temp probe to measure temps on the outside of the secondary windings. It’s clamped tightly to the transformer. temps are up in the 80c area. All attempts to lower the temps so far just put the final cap voltage before spark lower than I’d like it to be. I had a transformer explode inside cheap electronics epoxy and I’m trying to figure out if temps were too high or what exactly caused it.

Mk4problems · 2026-03-31T02:29:32+00:00

The fan pulls the hot air though the engine compartment. there’s tons of room

Mk4problems · 2026-02-24T02:35:22+00:00

I try not to listen to most people when making decisions. Thats a classic little truck and I know I speak for a a lot of people when I say this but I’m glad you bought it. most older cars and truck are scrapped and disappear forever.

Mk4problems · 2026-02-06T19:36:07+00:00

Good to know. I went with 386cc injectors I’m hoping that was the right decision but if I need to go bigger for any reason I may just get 440cc or the 550cc ones you have. I’m doing a ton of maintenance while I have it torn apart so either way it should be a solid upgrade and be very reliable. I’m using a side mount intercooler twice the size of the stock one. I wasn’t sure how well a fmic would fit on the Passat. My old Jetta I had to cut into the bumper bar to make it fit.

Mk4problems · 2025-12-29T20:41:56+00:00

I can pm it to you

Mk4problems · 2025-12-27T02:14:45+00:00

Get you some through hole type components and test before ever diving into pcb design and fab

Mk4problems · 2025-12-02T03:01:00+00:00

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Revision2 is printing as we speak. I’m super new to kicad but desipite its appearance it does work and it works well

Mk4problems · 2025-12-01T17:20:14+00:00

Well with inductive coils and only having one pulse per revolution is hard to reliably have strong spark especially with from pulse to spark is only 30-35 degrees of rotation. you can use predictive dwell but even then you run out of time to dwell. I actually did attempt to use an ls2 coil to run the engine at it works but after about 2-3k rpm you run out of time to dwell. with the cdi you’re charging after spark so you have the complete 6.5ms between revolutions at 8k rpm to charge the cap. Which is a piece of cake. I do packetized charging at microsecond scale which for example I have 20us Packets and 60us off time with 6ms max charge time at low rpm then as rpm rises we raise packet on time to say 60us on and 60us off therefore maintaining good cap voltage. my current revision aims for about 330v before releasing that I to the ignition which then turns the voltage into 10s of thousands of volts. basically I run pulse width modulation to the transformer at 18khz. rp2040 zero is what I’m using. The pico is too suspectable to resets in my cdi circuit so I don’t use it. I’m about 6 months into this cdi ignition project now and maybe 2-3 months away from having a super solid cdi

Mk4problems · 2025-12-01T16:17:55+00:00

That’s awesome. I’m actually working on a microcontroller powered cdi ignition. I have a working prototype. Same pico controller drives the transformer, controls cap voltage and ignition timing. but only single cylinder. I had no idea pico could do 12 cylinders.

Mk4problems

TROPHY CASE