[Diy_efi] RE:Photocoupler?

[Tony Petroski]

well, first of all i wanted to use the photocoupler to make my own
pulse width meter. Yes, the idea of using the photocoupler came from
you Steve. I am not an electronic expert but i just don't know any
other ways of being able to tap into the injector circuit in the
effort to workout pulse widths without affecting the performance of
the injector. Looking at the datasheet, the photocoupler doesnt seem
to use much current. The photocoupler i was gonna use was not the
bipolar one because i can't find it in australia. Only the single
polar direction. And because i thought it doesn't use much current i
wanted to apply it to the OEM injector circuit. Now using the
photocoupler opens up the idea of using it to drive extra injectors on
a separate ciruit. But i mostly need it to generate a TTL signal that
can be interpreted by a micropic chip.

Now that Steve has replied, i have contracting reports. Steve states
that his design pw_meter.jpg the photocoupler is ok. 

Yet Bruce Roe states....

I hope you are not planning to use a photocoupler input 
diode in series with a fuel injector.  The current may blow 
it up, if not the turn off spikes.  The voltage drop across an 
LED is rather high; probably will affect injector operation.

Could someone clear this up ? Or provide alternate ways in generating
TTL signals from existing circuits ? i.e. like to log. Say we have to
microchips communicating between TX/RX 0-5 Volts, & i want to log the
traffic over teh data lines via a third microchip. What can i use to
tap into the circuit without affecting (minially) the circuit?



eagerlt awaiting reply,



tony


-----------------------------------------------
Tony PETROSKI (Postgraduate)

Bachelor of Engineering in Mechanical (BE Mech)
Master of Computer Studies (MCompStd)
University of Wollongong NSW 2522 Australia
Mobile: 0402 297 106 Email: tp11 at uow.edu.au
-----------------------------------------------


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