Re: electrical deaths

On Thu, 5 Dec 2024 02:21:03 +0100, "Carlos E.R."
<robin_listas@es.invalid> wrote:

On 2024-12-05 02:02, Joe Gwinn wrote:

On Wed, 4 Dec 2024 22:25:19 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
 

Joe Gwinn <joegwinn@comcast.net> wrote:
>
[...]

>
Measuring winding DC resistances with probes did not work - contact
resistances too large and unstable.

>
Feed a constant current through the winding and then measure the
volt-drop with a pair of probes on the wires themselves, so that the
volt-drop of the terminal contact area is not included in the reading.
>
That is a standard four-terminal measuring technique used for low value
resistance.

 
I do have a 6.5-digit bench top digital multimeter.
 
The problem was that I didn't have four hands, and clip leads were too
flaky as well.  All such problems were solved using the 6-bar terminal
strip.

>
How about using AC from a signal generator?

I do have the equipment to that, but it wouldn't make any difference.
The contact points are tiny (very low capacitance and inductance), but
with a stuttering series contact resistance.

This was the first time I had encountered such a black-box problem to
solve.  If I had to do it again, I'd do it differently.  One thing
would be to use a small transformer to excite the windings with 24 Vac
60Hz power, and go around measuring voltages, and so on.  I developed
another method that needed only electrician skills and tools, but
don't recall the details.  But still have my notes.

Joe Gwinn