[Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?
niche at iinet.net.au
Tue May 24 01:13:50 CDT 2005
First sorry for the apparent obtuse meandering of my post on the subject,
I might put this down to a couple of stubbies of tooheys dark stout or
plain mental laziness - cant recall or admit to either exclusively ;-)
What I'm saying is:-
a. I'm continually pleased with diversity and people articulating
alternate solutions to technical problems.
b. I'm amused (a little) that the technology used to handle a
non linearity is developed initially to circumvent non linearities.
c. There is nothing wrong with using an opamp, they are cheap
and readily available but dont help us think of value of first principles.
d. There are simpler methods one would sensibly gravitate to in
a commercial environment which one might not bother with
because the thinking of using an 'out of the book' circuit such
as a comparator is mostly done for us, so we dont have to think
that much... ;)
People happily use opamps and the derivative comparators, to
deal with non linearities such as the P & H issue listed recently.
I find it interesting to recall that there has been considerable
development of opamps over many years so they can provide a
function which is as linear as possible yet the opamps themselves
use a huge number of non linear devices internally - nicely arranged in
combinatorial fashion to cancel out as many of these non linearities
Yet, if we can focus on one or two of the internal devices such
as the diode or transistor we can sidestep the complex opamp
and use the non linear device directly, derivative of the diode
being the light emitting diode in the form of an opto.
However, since devices like opamps are the black boxes and are
economical I also find it ironic there are hundreds of non linear
devices inside the opamp which makes it linear and the designer
circumvents this to put the opamp into the task of a comparator
which is hugely non linear but ".. theres nothing wrong with that..."
Its the overall above paradigm I am chuckling at and admittedly
not articulating that well in my last post or even this one - maybe...
cest la vi
At 09:16 AM 24/05/05, you wrote:
> Alright, I too would like to see what Mike is talking about. I am as
>green as they come, and here to learn. What really worries me, is I
>don't understand what Mike is saying. I hope that maybe he could put
>me on the path. I am really wanting to understand the non-digital
>circuity. I am sadly lacking in understanding. I would love to see
>a more elegant way of doing it. I've got the time. I seonded it.
>> Nothing personal Mike but would you be willing to explain how YOU would
>> do it?
>> Could you also explain in simpler language what you were talking about in
>> your post with its most impressive language(see below).
>>> -----Original Message-----
>>> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
>>> Behalf Of Mike
>>> Sent: Tuesday, 24 May 2005 03:37
>>> To: diy_efi at diy-efi.org
>>> Subject: RE: [Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?
>>> At 12:40 AM 24/05/05, you wrote:
>>> >there are a lot of ways to do it. That's how I managed it.
>>> Nothing personal, I was chuckling (as it were) at that very
>>> point, there are a huge number of ways one could implement
>>> an instrument with hysteresis. Most common way is certainly
>>> variations on opamps, differential or single ended. I've seen
>>> some doozies in my time, the thing I find curious is the
>>> efforts to go and handle a hysteresis by a contrived device
>>> like an opamp - a device created to circumvent many non linearities
>>> when the simplest unitary devices suffice quite well in as much
>>> as the non-linearities can be selected so easily to match the
>>> task without needed any opamps.
>>> I just find it ironic the very devices crafted to be as linear as
>>> use inherent nonlinear devices more suited directly but, still
>>> that a complex device like an opamp is so cheap and readily
>>> available when simpler devices might be considered elegant by many
>>> engineers but the sad thing is the time spent explaining how to use
>>> them is worth more than the opamps, or even the articulation herein.
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