[Diy_efi] New MegaWideband schematic

[Perry Harrington]

On Wed, Jul 17, 2002 at 12:48:37PM +0200, Jorgen Karlsson wrote:
> Hi,
> 
> Did I miss something?
> 
> I took a look at the schematic and I can't find any current regulation
> (other then R12, but that will not regulate current very well) or current
> sensing for the Ip current. I can't see how it will work without it.

It's all done using PWM.  It uses the same principal as the MegaSquirt and Bernd's
DDL.  The current is 'known' for the Ip as a percentage of max (6.1ma).  For
the heater, we know the heater's impedance at various temperatures, and thus
can regulate current.

It was the consensus that you can't properly heat up a UEGO using an LM317
regulator circuit, it won't supply enough current at the correct voltage to
work.  My own bench testing has shown this to be true.

> 
> If we want to keep a minimum part count we can measure the voltage drop over
> R12 and take an average. An analog filter could be simpler but that would
> add parts.
> 
> If you are interested I can mail you my latest digital WB controller
> circuit, it will need a sanity check anyway. It should work and it includes
> temperature sensing on the sense cell to be able to use a Bosch sensor. It's
> operation is quite different from yours as it use a regulated ip current.
> Feel free to rip what you want from it.

Mail away, the more info out there, the better.  I think it's also important
that as much prior art on these things is released so that companies don't patent
the most accessible ways for DIY folks to do stuff.

> 
> Jorgen
> 

--Perry

-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi