Automotive scope vs. O'scope

I 'm contemplating purchasing an oscilloscope for amateur radio uses
and general electronics tinkering etc. But I also enjoy working on
automotive electronic systems etc. My question is, can a regular
oscilloscope be just as useful when diagnosing automotive electronic
problems such as fuel injection, ignition, sensor related problems etc.
as can a dedicated automotive scope, or would a dedicated auotmotive
scope such as a Mastertech or Snap-On be more useful? Thanks for help
in advance. B. Taylor

On 16 Mar 2005 11:11:57 -0800, wrote:

>I 'm contemplating purchasing an oscilloscope for amateur radio uses
>and general electronics tinkering etc. But I also enjoy working on
>automotive electronic systems etc. My question is, can a regular
>oscilloscope be just as useful when diagnosing automotive electronic
>problems such as fuel injection, ignition, sensor related problems etc.
>as can a dedicated automotive scope,

Yes.

And if you can find a decent delayed sweep scope second hand,
it's better than an automotive scope. If you can't afford a multi
channel input you can probably build one with IC switches that will
allow you to monitor 4 fuel injector pulses at once etc. Automotive
waveforms are so slow relative to the capabilities of modern scopes
that they have no problems handling such signals in multiplex.

wrote:
> I 'm contemplating purchasing an oscilloscope for amateur radio uses
> and general electronics tinkering etc. But I also enjoy working on
> automotive electronic systems etc. My question is, can a regular
> oscilloscope be just as useful when diagnosing automotive electronic
> problems such as fuel injection, ignition, sensor related problems
etc.
> as can a dedicated automotive scope, or would a dedicated auotmotive
> scope such as a Mastertech or Snap-On be more useful? Thanks for
help
> in advance. B. Taylor

DC voltage is DC voltage, so any voltage meter will *work*. One big
difference with automotive use targeted labscopes is that they employ
some sort of glitch detection feature(s) that a plain old benchtop
scope may be lacking. Auto lab scopes mostly if not all are digital
storage types, so you can review a trace over a span of time if you
wish, with something like 10 or 20 ms between screen captures. They
usually have auto specific setup "macros" selectable via menu. They
typically default to DC and have an auto range function.

Now for a possible problem: 10 Mohm input impedence is a standard with
auto scopes and meters. I once had an old simple digital one-channel
scope that would kill engines when I tapped into the vane airflow
sensor wire (on Toyotas). I measured the input impedence of that unit
and found 4.3 Mohms. If I had not experienced that phenomenon for
myself, I would have thought 4.3 Mohms to be sufficient -- but you can
see it caused problems with that particular low current (and
unregulated) signal.

Toyota MDT in MO

Comboverfish wrote:
> wrote:
> > I 'm contemplating purchasing an oscilloscope for amateur radio
uses
> > and general electronics tinkering etc. But I also enjoy working on
> > automotive electronic systems etc. My question is, can a regular
> > oscilloscope be just as useful when diagnosing automotive
electronic
> > problems such as fuel injection, ignition, sensor related problems
> etc.
> > as can a dedicated automotive scope, or would a dedicated
auotmotive
> > scope such as a Mastertech or Snap-On be more useful? Thanks for
> help
> > in advance. B. Taylor
>
> DC voltage is DC voltage, so any voltage meter will *work*. One big
> difference with automotive use targeted labscopes is that they employ
> some sort of glitch detection feature(s) that a plain old benchtop
> scope may be lacking. Auto lab scopes mostly if not all are digital
> storage types, so you can review a trace over a span of time if you
> wish, with something like 10 or 20 ms between screen captures. They
> usually have auto specific setup "macros" selectable via menu. They
> typically default to DC and have an auto range function.
>
> Now for a possible problem: 10 Mohm input impedence is a standard
with
> auto scopes and meters. I once had an old simple digital one-channel
> scope that would kill engines when I tapped into the vane airflow
> sensor wire (on Toyotas). I measured the input impedence of that
unit
> and found 4.3 Mohms. If I had not experienced that phenomenon for
> myself, I would have thought 4.3 Mohms to be sufficient -- but you
can
> see it caused problems with that particular low current (and
> unregulated) signal.
>
> Toyota MDT in MO

Thank you to those that replied. I do appreciate the help. Does anyone
know if the automotive dedicated scopes have a database of known good
screen captures, so that you can quickly compare your current screen
capture to a known good screen capture for comparison? Thanks again.
B. Taylor