I’m sure I can do that but I really really want to do this as an ignition circuit. This is a wonderful learning experience for me and it is an act of service
I’m near Akron and Cuyahoga Falls

I’m relearning some long forgotten skills and learning new ones and my teacher has an English accent. It does not get any more awesome… except for when it works.

I think I have a circuit in an old magazine, a magazine that is now out of print,, called "Strictly IC". It was about building model engines, and they had a couple of different ignition modules they came up with.

I thought you were just interested in getting this running. There are simple off the shelf auto parts store ways to do this too.

Just another link to the problem. https://www.homemodelenginemachinist.com/threads/model-engine-cdi-easy-and-cheap.31128/

 

I think I have a circuit in an old magazine, a magazine that is now out of print,, called "Strictly IC". It was about building model engines, and they had a couple of different ignition modules they came up with.

I thought you were just interested in getting this running. There are simple off the shelf auto parts store ways to do this too.

Just another link to the problem. https://www.homemodelenginemachinist.com/threads/model-engine-cdi-easy-and-cheap.31128/

This is a great article. Thank you!

Holy Crap it's the motherload of schematics and detailed write-ups.

I highly encourage everyone to read the link and look at the files posted. There might very well be a eureka moment here.

- Mark

We could take the 12 - 400VDC board I have and insert it in the red box area or use the transformer and parts located on the board for this design.

There look to be some non-labeled transistors shown and I don't see a part number for the 8-pin inverter but that's common enough... Can we draw this up in the simulator and possibly have a PCB constructed if it checks out?

 

Please show me again what 555 circuit I need to build. I’ve checked in the lab and I don’t have any 2N7002, RFN10NS8D, BSB012N03LX3 or the transformer you reference. I wondering I can swipe these parts from a computer power supply or some other junk I have laying about….

For the avoidance of doubt and confusion I've redrawn the 'test bed' below and suggested a test procedure...



Test Procedure:
Using the wall-wart as supply, with the jumper installed on the HV module and the output of the 555 disconnected from the HVmodule, monitor the 555 output and the HV out. The 555 output should go to >10v on the negative pulse from the sensor and stay high until after the positive pulse from the sensor has triggered the spark and the HV is recovering, like this. If not, adjust the resistor R1 value larger to increase the width or smaller to decrease the width...


Once that is right, remove the jumper and connect the 555_out to the module. You should now see the HV being blanked, but it should still recover well before the next pulse, eg:



If that looks OK, then maybe risk trying it on the battery....

[edit] for the HV probe, that should be via a x1 scope probe for 100:1, a x10 probe gives 1000:1. I used an old Biro (pen) casing, soldered the 3 resistors in series with about 1" of lead between them with a 1/4" piece sticking out the pointy end and sealed that with silicone sealant. At the other end I brought the ground lead of the 10k resistor out the side of the case and formed a loop in it to make it easy to clip the ground lead of the scope probe too and did the same with the probe tip connection (10k/47k junction) out of the end, sealing it with silicone too. Finally I cut a circle about 2" dia out of a plastic (HDPE) container as a finger guard and attached it an inch or so from the HV end with sealant to stop fingers getting too near HV.

 

OK - Thanks for the clarification notes. Today after work I will spend some time in the lab and slap this together (if I can get the diodes... I may have to order them. I have the 1N0007 ones... at any rate I'll set this up and let you know how it turns out. Let me know if you want me to mail you one of the HV power supplies.

 

This is a great article. Thank you!

Would you want me to look for the schematic/article in the magazine as well? Even though it was for a model engine many people built it and it worked.

 

Huge apologies. I left the power supplies at home this AM. I feel terrible.

when I was bench test

Would you want me to look for the schematic/article in the magazine as well? Even though it was for a model engine many people built it and it worked.

Sure. At this point I’m excited to see multiple examples of how people have solved this.

 

Making a little progress

 

Sure. At this point I’m excited to see multiple examples of how people have solved this.

I'll dig out the boxes and look for it, may take a day or two though.

 

Minor hiccup. My father came by and took the trigger coil to his house. Is there a way I could simulate the trigger? Ac low Hz?

 

Everything but the coil and trigger.
So frustrating

 

Question: the two 1uF caps - can they be small voltage? Currently I have 400v rated ones in there

 

Question: the two 1uF caps - can they be small voltage? Currently I have 400v rated ones in there

Yes, 16v or more.

 

Ok. I’ll be starting the test procedure in about 1.5 hours. I have everything mocked up except having a coil and a spark plug.

 

Ok. I’ll be starting the test procedure in about 1.5 hours. I have everything mocked up except having a coil and a spark plug.

Hmmm, well without the coil & plug you wont be using any energy out of the caps on the booster so its not going to give you much info. Replace the coil with a 500ohm resistor of a moderate wattage rating.... as during the 'spark' it'll be handling about 100W for about 2mS or an average of about 1W at 500rpm. A few 1/2W resistors in parallel or something similar might work and keep the 'revs' as low as possible so they have time to cool between sparks..

 

Minor hiccup. My father came by and took the trigger coil to his house. Is there a way I could simulate the trigger? Ac low Hz?

missed this one.... a signal generator giving +/- 6v square wave at 50Hz?

Or another 555! Replacing the pot with a 68K gives 1000rpm approx.

 

Ok cool. I have a resistor box that I can dial into anything. Makes it easy.

 

Here is what I’m getting from the above circuit with the pot set to 100k

 

This is the output at 68k

 

Here we go
68k on pot

probe properly grounded

 

Pot set to 100k