How do I reduce ignition noise. (HELP!!)

[Walter Petermann]

Chris Vandrachek wrote:
> 
> To all in EFT land:
>         I have recently designed and built a simple EFT system based on a
> Mot. HC12.  All has gone well until now.  I can't keep the MCU from
> reseting whenever the ignition fires.  I am only a sophomore EE student so
> I don't exactly know where to start.
> 
> Here is a quick outline:
>         -The MCU is physically isolated from the coil etc (5ft), but they
>         share the same battery.
>         -I'm using a standard points ignition...I'd do a electronic, but I
>         have to be done by this Friday.
>         -The MCU supply is regulated with only a LM2935 (an automotive
>         specific device).  Only a .1 cap on the inputs.
>         -It seems that reset occurs most whenever a open arc is present,
>         arcing in distributor cap included.
>         -The problem is independent of my triggering pulse (from
>         coil)...so I'm guessing it is due to voltage spikes/drops or it is
>         "in the air" (EMF?).
> 
> I don't know what to do and I gotta have the done by Friday for a design
> competition.  Any advice would be greatly appreciated!!!
>         Thanks,
>           Chris Vondrachek
>           EE student, University of Portland
>           chrisv at egr.up.edu

Chris Vandrachek wrote:

> 

> To all in EFT land:

>         I have recently designed and built a simple EFT system based on a

> Mot. HC12.  All has gone well until now.  I can't keep the MCU from

> reseting whenever the ignition fires.  I am only a sophomore EE student so

> I don't exactly know where to start.

> 

> Here is a quick outline:

>         -The MCU is physically isolated from the coil etc (5ft), but they

>         share the same battery.

>         -I'm using a standard points ignition...I'd do a electronic, but I

>         have to be done by this Friday.

>         -The MCU supply is regulated with only a LM2935 (an automotive

>         specific device).  Only a .1 cap on the inputs.

>         -It seems that reset occurs most whenever a open arc is present,

>         arcing in distributor cap included.

>         -The problem is independent of my triggering pulse (from

>         coil)...so I'm guessing it is due to voltage spikes/drops or it is

>         "in the air" (EMF?).

> 

> I don't know what to do and I gotta have the done by Friday for a design

> competition.  Any advice would be greatly appreciated!!!

>         Thanks,

>           Chris Vondrachek

>           EE student, University of Portland

>           chrisv at egr.up.edu



 Chris,

 I would like to help but would need more info. My first

guess (usually wrong!) would be to look at the circuit

between the coil and the MCU.

Have you tried an inductor in series with the power supply

of the MCU board?

 If you like, email a circuit diagram.



  Walter