I am constructing an electronic ignition system for model engines.
Update january 25 2005, click here
Planned spec:
Run from a 4,8, 600 mAh battery
Use CDI to get a hot spark, even when starting.
Electronic advance
Minimal part count
Possible extra's;
Ignition on/off by RC control
The ignition will be based on a free running oscillator to generate the CDI
voltage, a SCR to control the fiering, and a PIC chip to control the advance. A
standard Modelectric coil is used. A hall effect IC reads engine position.
Block Diagram
September 26 2003
First prototype built, crude construction, but it works.
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Components used; 1 Transistor BD242B |
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Waveform from prototype: Upper track is the trigger pulses Works wery well. |
Schematics
Toroid coil
The ferrite core is a very common type; it is taken from an old computer. It was
used as an RFI suppressor on the motherboard cables.
It has an outer diameter of 2,5 cm.
The 3 windings is made like this;
L1 20 turns of 0,5 mm
L2 10 turns of 0,1 mm
L3 450 turns of 0,1 mm
All windings must go in the same direction, and must not be too loose on the
ferrite core.
Wind L3 first.
When done, put on some lacquer to fix them.
The components values are form my prototype, but none of them is critical, use
what you have…
To trigger the unit, use a Hall Effect device with logic level output.
Mount a small magnet on the flywheel, and position the Hall Effect device so the
magnet will trigger it.
The next step is to make the advance control. I will use a PIC microcontroller for this, probably a PIC12C508/509.
Fell free to send send me a mail, if you have any questions.