Hi Tony,

Sorry to keep you hanging -- I found that Circuit Cellar article (hope you
have access to this issue):

Issue 138, January 2002

Title: Building a Fuel-Injection ECU
Abstract: Trying to replace or upgrade an ECU with commercial offerings can
get
        expensive. Instead, Bruce and Al take you through the process of
        building your own fuel-injection ECU. They start with plenty of
        information on electronic fuel injection systems and how everything
        works.


Ok, I was right about being related to Motorola, but the schematic was on
the right-hand side. :)

See Figure 1 on page 13 for the regulator circuit with transient protection
etc. It's a 5 volt linear regulator however.

Page 16: SHOW ME THE CIRCUIT - Text that describes the noisy electrical
system of an auto.


Hope this helps.

Best regards,

Ken Pergola




-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of NaB25J@AOL.COM
Sent: Friday, August 22, 2003 9:36 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]: Automotive Stereo Power


Hey, everyone

How clean of a source is the 12v stereo power supplied by a car? I've
noticed it can vary from (in my car) 11.5v off the battery to almost 14v
when the engine is running. I'm thinking that it's not a very well regulated
source. So how likely is it that spikes and noise can make their way into
the circuit being powered? The vehicle in question is a 1991 Geo Prizm
(basically a Toyota Corolla of the same era).

I ask because I'm not sure what kind of protection might be needed in a
circuit to be powered by such a source. If it's a significant problem, what
can be done about it?


Thanks, and happy Friday

-Tony

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