[Diy_efi] operating 02 on 12volts

[rr]

If using batteries have to keep in mind that the heater 
draws ~1A of power.

Yes to using the original or any other heater control circuit.
All you need to do is turn on the opto-coupler (ISO1) once
the heater is up to temperature. There is no electrical connection
between the UEGO control and heater control circuits.

BobR.


George Livanes wrote:
> 
> I would like to run my 02 on a 12volt battery rather than the vehicles 14
> supply
> Options appear to be
> 1.  Add two rechargeable d cells in series with my 12 volt battery (as
> suggested)
> 2.Build a switchmode power supply  with 14volt output.I visited the National
> site (as suggested) and used the simple switcher software.The resultant
> circuit was not practical as the ferrite core,ic ,and schotky diode are not
> available locally in one off quantities .Also ideally requires careful
> design of pcb and possible shielding.
> 3.I remembered the original 02 circuit used a power FET which,if switched
> hard on, should result in voltage drop across the series 0.25 ohm resistor
> of only about 400 millivolts.This should result in a little over one volt
> more than the using the newer low dropout regulator design.
> I realize that performance may not be quite as good but otherwise  the
> circuit provides a 10 volt limit and other features found in the newer
> design.
> My question to Bruce Roe and other guys is can i use this heater circuit
> instead  of the newer design ?????????(with some minor mods).
> 
> Regards George
>

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