extra long thin beefy scope probe for poking about? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: October 04, 2022, 04:13:30 am
content: I should use a oscilloscope more often when I investigate circuits, the problem is usually the scope probe is a too short.Is there a long thin scope probe that is kinda like a pencil that has a thick sharp tip and good frequency response to a few MHz? For like investigating stuff thats hard to take apart (come in from a weird angle to get something under a transformer). I need to work top side because constantly flipping something for scope measurements is annoying when trouble shooting. I also need the center pin to be like a multimeter probe thickness so it does not bend easy and can handle a bit of prying action. I thougth about making a DIY one from brass tube and heat shrink but I wonder if there is a commercial solution.

author: jonpaul
author_rank: Super Contributor
timestamp: October 04, 2022, 05:02:12 am
content: Never had this issue, send a pix the problem.we just Use slip on tip extension on old Tek probes.Jon

author: Terry Bites
author_rank: Super Contributor
timestamp: October 05, 2022, 01:16:30 pm
content: semi rigid or rigid coax inside heatshrinkconnected to a tiny diecast box with compensation parts.See the Pomona cataloghttps://www.pomonaelectronics.com/products/boxes/boxes-with-connectorsBuy a ready made semi rigid with SMAs or what ever, cut it - make two probes! Sell them!Tha cable datasheet will give you pF/m. Go figure.https://www.electronics-notes.com/articles/test-methods/oscilloscope/scope-probe-compensation.phpSee the Dave show.

author: ajb
author_rank: Super Contributor
timestamp: October 05, 2022, 05:10:32 pm
content: There are probes that have replaceable tips, like this one:https://www.pomonaelectronics.com/products/products/250-mhz-x10-oscilloscope-probeShould be possible to fit a replacement tip of your choice. Maybe the ones that come with these fit?https://www.pomonaelectronics.com/products/dmm-test-leads-and-probes/precision-electronic-probe-full-set-5-replacement-tipsAlternatively, you just need some wire of the appropriate OD with whatever tip profile you want formed on the end. Stainless is probably preferable for its corrosion resistance and hardness in spite of its poor conductivity (which shouldn't particularly matter here), should be easy enough to form a basic pyramidal point by hand using abrasive stones under a jeweler's loupe.Note that "good frequency response to a few MHz" depends a lot on the ground connection, though. Increasing the length of the tip means increasing the area of the loop formed by the tip+ground connection, so that will be a fundamental limiting factor regardless of how good the probe itself is. Of course there are plenty of signals you might be probing where a few inches of ground lead isn't a dealbreaker, in which case you could use something like this and fit whatever probes you want for both signal and ground:https://www.pomonaelectronics.com/products/products/oscilloscope-probe-tip-adapter(somewhere on the forum I've posted about a DIY version of this made from probe-tip-to-BNC adapters as well)

author: alm
author_rank: Super Contributor
timestamp: October 05, 2022, 09:27:36 pm
content: Prying with a scope probe?I think the closest commercial product might be the tube-era probes that were made more for the scale you appear to be working at. For example theTektronix P6006(see attached picture with all accessories). Obviously these are only available used. You might have to buy accessories separately. Note that the fat tip is on a flexible, rubber boot.Other than that I'd look at the industrial scope probes, but I looked at theStaubli IsoProbe series, but they are not especially long or sturdy. Generally oxide-puncturing is considered more important for scope probes than prying. Another option might be a high voltage differential probe, which will generally have 4mm banana plugs as inputs, so you can use your favorite 4mm accessories. Due to their lower input capacitance they should be slightly less sensitive to having extra inductance in front of them than passive probes.

author: artag
author_rank: Super Contributor
timestamp: October 05, 2022, 09:49:51 pm
content: HP / Agilent / whatever 1165A probes have what they call a browser tip as well as the usual hook/spike. It's a bit longer than usual but has a springy pointy tip that's very good at not slipping.They're pretty expensive but the tip as actually an ATE probe aka pogo probe. If you make a probe extension with a pogo holder (just a long springy socket, though they exist as a product) then you can fit any of a wide range of pogo tips in it and push-in replace if your prying gets a bit too enthusiastic.Rather than make the whole compensation network, cable etc. I'd be inclined to take the probe tip off a common probe, cut back the tip to the metalwork, hack a pogo socket on the end and then heatshrink over the top.The other difficulty with browsing is that the earth lead gets to be long, or has to often be moved. In non-critical situations I even use the other probe's earth, but that can give you a lot of spurious junk from the huge pickup loop.

author: coppercone2
author_rank: Super Contributor
timestamp: October 06, 2022, 12:28:10 am
content: Quote from: alm on October 05, 2022, 09:27:36 pmYes I have a P6006 HP Equivalent actually, I want like a thinner version that's threaded. I wonder if they made a improvement with modern plastics?I have only of one of the tips, maybe the solution is to acquire the other tips. I don't have any tips I don't think, I think someone just wedged a aligator clip on it , I never used it, its kind of similar to the fluke scope meter probes. Been meaning to do something with that now that I think about it. It needs a penetrator tip. It would be the best scope probe to perform a modification on. I don't need to worry about the center pin on that one. I got it in a eBay accessories lot maybe 10 years ago.I had it in the back of my mind but it looks like it might be the best solution, it looks like engineering went in a different direction."the pool que"Only problem i recall is that the cable might be a little bit stiff. Has anyone ever replaced it? Need to research scope cable replacements.I think that looking into the older probes will be the best thing. The RG stick thing is a OK idea but the problem is the center pin is still really weak.

author: jonpaul
author_rank: Super Contributor
timestamp: October 06, 2022, 09:38:12 pm
content: Bonjour cher Copper one,We used Tektronix P6054 and similar 1980s probe with slip on tips and adapters like 206-0114-00 see photoshttps://w140.com/tekwiki/wiki/P6054The sturdy wire tip can be straightened and a solid bus wire added, we used Téflon sleeve insulationThe P6006 tube Era probe from 1960s are way too large, thick stiff cables.Jon

author: alm
author_rank: Super Contributor
timestamp: October 06, 2022, 09:44:56 pm
content: Quote from: jonpaul on October 06, 2022, 09:38:12 pmSure, but probably your least bad bet for a scope probe that can survive "a bit of prying action".

author: coppercone2
author_rank: Super Contributor
timestamp: October 06, 2022, 11:13:52 pm
content: well partially the reason is to see if mechanical pressure does something to a signal