[IMSAI Guy] wants you to build a non-contact scope probe. The cost? Assuming you have a bit of wire and a regular scope probe, it won’t cost you anything. Why do you want such a thing? You can see what he does with it in the video below.

The probe is really just a coil with little slip-over coils that grab it. You can stick it on and remove it just as easily, so you don’t have to sacrifice the probe for normal use. It won’t give you high-accuracy readings, but if you want to sniff around a circuit without directly connecting to it, it will do the trick. If you are too lazy to make a coil, you can even clip a ground lead to the probe tip, although that won’t work quite as well.

#1853 Free Oscilloscope Probe Attachment
https://www.youtube.com/watch?v=yCfeVyQD5sY

How to make and Calibrate a Inductive Current Probe

Making connection to your device under test is critical to accurate measurements. Learn the basics parts of the probing system and what they do.

https://beyondmeasure.rigoltech.com/acton/fs/blocks/showLandingPage/a/1579/p/p-0032/t/page/fm/0

DIY oscilloscope probes that are easy to build, low cost, high bandwidth, robust, and flexible. Downside here is low impedance but in most cases it is worth the tradeoff.

https://nihtila.com/2019/03/16/tip-3-robust-high-bandwidth-passive-diy-probes/

Will these DIY scope leads compare to bought oscilloscope leads? We give them a test on CAN bus using the PicoScope 2204A. Making these oscilloscope leads was very easy, and the parts to make them very cheap! All we need is a BNC adapter and 4mm banana connector.

Introduction

Ironically, even as the 10x passive probe is the most commonly used probe with an oscilloscope, it is often misunderstood and used incorrectly. This Application Note explains how to get the most out of it by avoiding common artifacts.
Best Practices for 10x Probes

There are five important best measurement practices to consider when using the 10x probe. Follow these guidelines to get the best performance with a 10x probe and avoid common artifacts:

Always compensate the probe using the calibration (Cal) reference signal on the front panel of every oscilloscope.
Always try to use a tip geometry that minimizes the loop inductance. A small spring ground tip or a coaxial connection to the DUT will reduce the ringing artifacts and extend the probing bandwidth to the highest frequency.
Always try to use a coaxial connection to the DUT to reduce radio-frequency (RF) pickup from the local environment.
When probing a low-impedance source, consider adding a 200-Ω series resistance to damp out the ringing from the tip loop inductance and the input capacitance of the 10x probe.
Always remember that the input impedance of the 10x probe is a 9.5-pF capacitance; it is not 10 MΩ.

The TMA, an international alliance of Test and Measurement companies, today announces a significant industry-wide decision to retire x1/x10 switchable oscilloscope probes in all new Alliance Member oscilloscope products, effeective from the start of Q3 2023.

This decision is backed by industry-leading oscilloscope companies as part of the Test & Measurement Alliance, they include Keysight, Tektronix, Rohde & Schwarz, Lecroy, GW Instek, Siglent, Rigol, National Instruments, Hantek, Owon, and Micsig.

This proactive measure comes as a response to growing concerns about the limitations and potential risks associated with switchable probes.