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This question already has an answer here:

To reduce the loop area and noisepick up, the GND lead of the scope probe is very next to the tip in the below probe:

enter image description here

I don’t have such probes and my scope probe GND leads are much longer alligator clips.

Does the type of probe in the photo have a name or is it homemade? And when is it used?

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marked as duplicate by bitsmack, Finbarr, Lior Bilia, Edgar Brown, Dwayne Reid Feb 9 at 1:08

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    \$\begingroup\$ That particular one looks home-made, but when I last purchased a 'scope probe it had one of those included in the package of accessories. Not sure what it's officially called though ... \$\endgroup\$ – brhans Feb 5 at 18:30
  • \$\begingroup\$ Do you know how it is made from a typical alligator lead one? \$\endgroup\$ – atmnt Feb 5 at 18:31
  • \$\begingroup\$ You don't make it out of an alligator lead clip - they're completely separate accessories. This one wraps around the barrel near the tip, while the alligator lead usually attaches much further up on the probe. If you want to make one, find some stiff wire, wind it into a coil of the same diameter as the barrel of your probe, and cut the end just long enough to reach the same length as the tip. \$\endgroup\$ – brhans Feb 5 at 18:37
  • \$\begingroup\$ Are they used for high freq measurements? \$\endgroup\$ – atmnt Feb 5 at 18:39
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    \$\begingroup\$ High frequency or low level. If I'm looking at microvolt level stuff, the wire on the alligator clip will pick up enough powerline hum to obscure the real signal. \$\endgroup\$ – JRE Feb 5 at 19:37
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This is not a "probe", this is called "ground accessory" to some old active probes like Tektronix P5100 etc. The shown is a hand-made accessory, but there were ground tips made of springy wire and officially sold by oscilloscope companies. An example of a smaller size ground contact,

enter image description here

or for Agilent probes (circled in red:

enter image description here

The purpose of these short probe leads is to decrease inductance of leads (ground in particular) and gain few dozens of MHz to overall probe's bandwidth. And to reduce unwanted parasitic interference from nearby signals. Here is the detail:

enter image description here

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  • \$\begingroup\$ Their purpose is to decrease inductance yet they are exactly in the shape of an inductor. Im confused:(( \$\endgroup\$ – atmnt Feb 5 at 19:59
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    \$\begingroup\$ No, the coiled part is supposed to lay tight on the ground barrel of the probe tip, so it serves the mechanical purpose only. The inductance comes only from the relatively short straight tip. \$\endgroup\$ – Ale..chenski Feb 5 at 20:05
  • \$\begingroup\$ I see the coiled part will be tightly joint to the ground barrel that explains my confusion. \$\endgroup\$ – atmnt Feb 5 at 20:07
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    \$\begingroup\$ @Hearth, yes, these spirals are still supplied with low-end sub-GHz probes. Better probes have pogo-pin accessories right from the active tip, or the ground attachment is done with gold-plated bronze wraps, and the best one have ground and signal soldered to the points of interest, and use differential mode or switchable "tri-mode", tek.com/datasheet/trimode%28tm%29-probe-family. \$\endgroup\$ – Ale..chenski Feb 6 at 3:22
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    \$\begingroup\$ Oh man, I have always wondered what spare part the spring is for, turns out it was never a spare part to begin with! \$\endgroup\$ – crasic Feb 6 at 7:53
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I've used such, either from Tektronix P6201 900MHz active FET probe (a 1970s era beauty) accessory kit, or ones I made from solder-wick.

With the probe's 10X attenuator slide on, the capacitance was 1pF. With 2cm of solderwick producing about 20nanoHenry inductance, the input LC resonance was near 1,000MHz and life was very good for examining what was really occurring on the PCBs.

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