http://www.analog.com/library/analogDialogue/archives/39-05/op_amp_applications_handbook.html

http://www.national.com/analog/amplifiers/application_notes


Hope this helps
Craig Smith


I hooked the current op amp non inverting circuit to the 555 circuit and
what really stunned me is it worked perfectly, including clicking the
injector, all the way from 12 volts down to a 5 volts supply.
If the mass air flow sensor is putting out the same voltage the mixture
would get richer as the 12 volts supply faded.

The FET driving the injector stops triggering around five volts input.

The only problem I can see is the five volt regulator in the mass airflow
sensor would shut off around 7 volts.

You could not say this about a computer system. The five volt
regulators would give up around seven volts.

In theory you could back up this EFI system with six D cell batteries.