[sdiy] look Ma, no hands! ??

[harry]

Typical of the little bag of parts is...
1) a coil spring that slips over the probe with the tip removed... and has
a sharp point. This is used to make a ground connection at the same time as
the tip connection. This will eliminate as much inductance from the measurement
as is possible with that probe.

Use this as a sanity check when you think the scope is lying to you from
inductive pickup in the ground lead.

2) little plastic caps... on of them is often slotted so the probe can rest on
ONE pin of a DIP package and not short to its neighbors... cool.

3) a cap that covers the ground sleeve... good for NOT shorting things to
ground...

BTW... I use either the ground clip (almost always) of the scope frame ground
(to the AC mains via the 3rd prong) but NEVER both. I recommend a "cheater"
plug that converts 3 wire to 2 wire mains. This IS a safety issue... Grounded
scope
chassis could flame spray you with metal from the disintegrating ground clip...
when you short it to a "hot" point by mistake...  UNgrounded chassis goes to the
potential
where you put your ground clip... now you could get a shock from the case...

The AC ground is always so noisy that you will NOT know what is circuit and what
is Noise. Our service techs do this all the time... then they call me.  "Got the
scope
AC grounded... yes... well DON'T !!!"

The only SAFE way to make measurements that may include the AC mains, is to use
a True Differential input on a scope (rare) and two probes, NO ground clip, and
the scope case Grounded.  OR use an active differential probe ($$$).

H^) harry

Mountain Man wrote:

> Oh, so *that's* what's that bag of little parts that came with the probes is
> for!  :)  Boy, do I feel sheepish.  Of course, if the B&K probes that I bought
> had come with some documentation ...  :(   Now I'm wondering what all those
> other little things in the bag are for.  Unfortunately, when I try to go to
> the B&K site to look for an "FAQ", my version of Netscape crashes while trying
> to load a plugin :(
>
> Anyway, thank you for all the very helpful comments  (I particularly like the
> idea of soldering on a needle - cool!)
>
> Elby
>
> Scott Bernardi wrote:
>
> > Most scope probes come with a "grabber" hook, and an alligator clip for
> > the ground connection. The grabber hook has a plastic housing that fits
> > over the pointy end of the probe. When you press down on the housing,
> > the grabber hook pops out. It's spring loaded so it can grab onto
> > component leads with no hands.
> > If your scope is missing the hooks, you might want to get some new
> > probes. Circuit specialists http://www.web-tronics.com/ has 'em.
> >
> > Mountain Man wrote:
> > >
> > > Hi, folks.  Yet-another-newbie-question <g>.   I got my new (old) scope
> > > a couple of days ago and am really having fun with it!  I haven't
> > > figured out some of the controls, but I'm making definite progress -
> > > it's seriously cool seeing my waveforms on the screen :)  I particularly
> > > love seeing the envelopes sit up and beg! <g>   My question is, how do
> > > you hold the probes in place?  I've been dedicating one hand to doing
> > > that, but when I start in on two-probe operations, I'm going to be short
> > > at *least* one hand!  The obvious solution that comes to mind -clip em
> > > on - doesn't seem like it will work (BTW, at the moment, I'm connecting
> > > to wire coming out of a jack.  I'm interested in solutions both for
> > > probing a wire, and probing on a board directly).  The probe tips are
> > > too teeny and delicate. I'm sure there's a simple and elegant way of
> > > going "no hands"  Another problem I'm having is that ground wire is too
> > > short on my probes.  Guess I'll just graft extensions on for that one.
> > >
> > > Thanks much,
> > > Elby
> >
> > --
> > Scott Bernardi
> > sbernardi at home.net