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I made these today...

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JimB

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As the title says, I made these:-

Springs 1.jpg

I made them from paperclips.
But why? What are they for?

The average scope probe looks a bit like this:-

Springs 2.jpg

There is a long grounding lead with a croc clip on the end.
This is fine for the average low frequency signal, but when you get up to a few MHz or are trying to look at sharp edges on pulses, the inductance of the ground lead can cause some strange effects.

To overcome this, a short ground connection is needed, and so, using a little spring made to fit the ground sleeve at the end of the scope probe:-

Springs 3.jpg

It is possible to make short connections to the circuit ground, and the point being probed.

The next problem comes in actually making the thing.
Just straightening out a paperclip and then winding it around the ground sleeve of the probe does not work.
There is some "springback" in the wire and it settles out at a larger diameter than you want and the spring just falls off the probe.
So with a bit of experimentation and measuring, I made this little jig:-

Springs 4.jpg

It is a piece of steel rod, the end has been turned down in a lathe so that the diameter is slightly smaller (0.010" actually) than the ground sleeve on the scope probe.
In the end of the rod is a saw cut.

To make the ground spring, I straightened the paperclip, put one end into the saw cut and wrapped the wire around the rod, leaving about 10mm of wire un bent, remove the spring from the rod and bend the 10mm free end to make the grounding probe end, cut off the end piece which was in the saw cut and voila!
A scope probe grounding spring.

So that is what I made, what did you make today?

JimB
 

ericgibbs

Well-Known Member
Most Helpful Member
hi Jim,
For ref only, I did see on another site a member posted a Copper version of the coil and 'probe', he used it on his soldering iron for de-soldering SMT resistor/caps.
Tweaking the separation of the iron tip and the probe to fit the SMT
E
 

Ian Rogers

User Extraordinaire
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Most Helpful Member
Good Idea...Fastest signal I use is 115200 ( baud )

So that is what I made, what did you make today?
I finally put a dual florescent light above my workstation... Sign of the times, I can no longer see what's at my fingertips...
 
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