Uh, guys? How many of us have LBCs with these oxygen sensor gizmos? I
don't own any. I suppose there must be some TR8s or even some 7s that have
them but which cars were actually equipped with them? What percentage of
all Triumph owners actually have to worry about them? I'm curious.
John McEwen
>Malcolm Walker wrote:
>> Hmm... a sound-card equipped computer can almost be used as a 'scope...
>> <ponder>
>
> Well, a scope is like a MIG welder, once you get one you
>are surprised you lived without.
>
> However the sound card ones have very limited input ranges,
>among other limitations.
>
>> > (in other words, analog meters actually use power from the circuit
>> > to move the needle, and the signal produced from the oxygen sensor
>> > is too weak to move the needle. Digital meters draw almost no
>> > current from the circuit they measure)
>>
>> Ugh. I think you're right. My cheap-o meter (the REAL reason why I
>> bought an analog) only goes down to 5V DC and 10V AC. That means I have
>> 1/5 of the scale to watch for 1 volt.
>
> Actually, it's a little worse than that.
>
> The problem is that the analog meters use the current from the circuit
>they are watching to move the needle. The voltage in the circuit causes
>a current in the windings of the needle movement that causes the needle
>to move.
>
> Because you are using a voltage to create a current, work is done and
>therefore power is consumed.
>
> Enter the humble O2 sensor, which creates a voltage based on some
>fancy chemistry but can not supply any meaningful amount of current. It
>can only supply the voltage to an open or near-open circuit, clip a
>voltmeter across it and the voltage will dip to about nothing.
>
> The term is "high impedance", which digital meters are pretty much
>universally, where only a few specially designed analog meters are
>able to be. Very very little current flows through the probes, so
>you don't disrupt the circuit you are watching.
>
>> When I'm rich and famous I'll buy a Fluke or similar beast. For now it's
>> the Radio Shack Special. :-(
>
> I'm a big fan of radio shack specials actually. I have a fluke 87
>which
>is a somewhat fancy fluke with backlighting and bar graphs and true RMS
>reading and all sorts of doo dads. I also have one of those credit card
>sized radio shack digital meters that runs on watch batteries. Guess
>which
>one gets used the most?
>
>--
>Trevor Boicey
>Ottawa, Canada
>tboicey@brit.ca
>http://www.brit.ca/~tboicey/
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