MarkySparky
- Aug 12, 2022
- 10
- Joined
- Aug 12, 2022
- Messages
- 10
Hi,
I'm reconstructing a CDI trigger circuit for an old Hit-n-miss engine.
There is a small coil that I'm calling the Trigger-Coil. On the flywheel there is a magnetic assembly consisting of two magnets separated by a few inches. There is a Strong magnet North UP followed by a weak magnet with South UP. I assume that this is a trigger signal and a reset signal to close the SCR for charging again.
I am trying to figure out what components to use in conjunction with this coil to fire my circuit. I cannot change the coil to a Hall effect sensor - I have to keep the coil and magnets. I've seen a few different designs for trigger circuits but I don't UNDERSTSAND the selection and sizing of the components.
My circuit has a 12VDC source that steps up to a 350VDC to charge the capacitor part of my circuit. currently, I can trigger the gate if I hit it was 12VDC (just tapping the SCR leg with 12VDC). The spark plug sparks. I need help with the trigger now...
Do you think that the Trigger-Coil has 12VDC going to it at all times and that the magnet passing by changes the voltage and fires the Gate or do you think that the Trigger-Coil and magnet generate a voltage spike by themselves that trigger the Gate to fire?
- Mark
I'm reconstructing a CDI trigger circuit for an old Hit-n-miss engine.
There is a small coil that I'm calling the Trigger-Coil. On the flywheel there is a magnetic assembly consisting of two magnets separated by a few inches. There is a Strong magnet North UP followed by a weak magnet with South UP. I assume that this is a trigger signal and a reset signal to close the SCR for charging again.
I am trying to figure out what components to use in conjunction with this coil to fire my circuit. I cannot change the coil to a Hall effect sensor - I have to keep the coil and magnets. I've seen a few different designs for trigger circuits but I don't UNDERSTSAND the selection and sizing of the components.
My circuit has a 12VDC source that steps up to a 350VDC to charge the capacitor part of my circuit. currently, I can trigger the gate if I hit it was 12VDC (just tapping the SCR leg with 12VDC). The spark plug sparks. I need help with the trigger now...
Do you think that the Trigger-Coil has 12VDC going to it at all times and that the magnet passing by changes the voltage and fires the Gate or do you think that the Trigger-Coil and magnet generate a voltage spike by themselves that trigger the Gate to fire?
- Mark
Last edited: