[Diy_efi] operating 02 on 12volts

[bcroe at juno.com]

Switch mode supplies can solve problems, but they can 
also create a whole new set.  I would stick to linear if it 
can do the job.  

I have a heater circuit which is designed to work under 
12V, and could get into high 10s if needed.  Of course 
it is not quite as simple and cheap.  I could send it 
to you.  

Bruce Roe

On Fri, 14 Jun 2002 00:29:47 +1000 "George Livanes" 
<gmt at zipworld.com.au> writes:
> 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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