EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: cdev on April 10, 2015, 11:41:45 pm
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So frequently i find myself wanting to measure signals in some arbitrary device and the thing that most frequently ends up being the barrier - is the barrier that is presented by the PITA of holding the probe and manipulating the device at the same time. So I guess I am asking about innovative ways to get your desired signal into your measuring device
What do you use?
test clips, probes, beds of nails, etc. Several times I've made little probes using a sewing needle or something, just because the target is so small. It also has to have some bite to stay in place.
My current one uses a needle and a ground clip attached to a length of mini coax held in a rubber dental pick held against the DUT by a rubber band strung between two screws sunk into a block of wood.
It works, kind of. Assuming i don't move anything. I guess its a 1x probe without frequency compensation.. Not so great.
I have real probes, but they are kind of bulky for the current arm. Tek (and probably other companies) make pro probe holders but they are insanely expensive. I guess that is kind of what I want a probe holder that will hold a probe in exactly the right spot with exactly the right amount of pressure to prevent it from moving around.
What do you do?
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First limit the types of signals you wish to observe, particularly voltage and frequency.
Then, since this is a standard problem, look at the major test equipment manufacturers' catalogues.
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The devices i've seen in that context are mostly too pricey for hobby use, at least for me right now.
It wouldn't make sense for me to spend more on a probe holder than I did on the scope!
A long time ago I saw an article by Bob Pease about making your own.
Does anybody know which article that was in?
I think I remember that the way he suggested to do it was using PCB material, which would be good, its light and strong and has a bit of springiness to it.
I could include the compensation by integrating the circuit into the PCB.
First limit the types of signals you wish to observe, particularly voltage and frequency.
Then, since this is a standard problem, look at the major test equipment manufacturers' catalogues.
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Lots of other threads about this
https://www.eevblog.com/forum/testgear/probe-positioners-any-good-recommendations/ (https://www.eevblog.com/forum/testgear/probe-positioners-any-good-recommendations/)
https://www.eevblog.com/forum/testgear/oscilloscope-probe-holder-with-vision/ (https://www.eevblog.com/forum/testgear/oscilloscope-probe-holder-with-vision/)
As long as you can come in from above a simple two leg holder using gravity to keep it in place works. If you absolutely need to come in from weird angles maybe you could solder a pogo pin on semi-flex coax (some people use it for a third hand as well).
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I made a probe holder for my scope probe, and the scope probe tip is a fine-pitch spring-loaded tip so makes probing very easy. Here's an image (I forget why the background is removed, sorry it makes it looks like it's floating, I must have wanted to use this for something else):
(http://www.colinoflynn.com/oldsite/tiki-download_file.php?fileId=90&display)
I've got some details including a video here: http://colinoflynn.com/2014/01/making-a-simple-scope-probe-holder/ (http://colinoflynn.com/2014/01/making-a-simple-scope-probe-holder/) . The base is a 'magnetic base' which you can get at all sorts of places, and is available in various sizes. I've got some smaller ones now.
The probe itself is a PicoScope probe, but is available from most of the manufactures too under their own name. Here's a comparison to a normal scope probe tip:
(http://circuitcellar.com/wp-content/uploads/2014/02/Figure-4-web.jpg)
The probe is the same as these ones:
*PicoScope TA150 (350-MHz bandwidth)
*PicoScope TA133 (500-MHz bandwidth)
*Agilent N287xA
*Teledyne LeCroy PP007
*Rohde & Schwarz RTM-ZP10 (NB: this is very slightly different possibly, the others are clearly all made by the same manufacture though)
One nice feature of the above probes is they sell little caps which make it easier to probe QFP packages too:
(http://media.digikey.com/Photos/Teledyne%20LeCroy%20Photos/PK007-012.jpg)
So it's possible to vaguely hold the probe with one hand that way :) See for example Lecroy's accessory list (http://cdn.teledynelecroy.com/files/accessories/pp007_pp008_accessorydiagram.pdf), but again they are the same upstream supplier that is making all of them. There is also a nice ground blade that connects to a piece of copper tape you mount on the IC for your ground connection when using the caps.
It's not the exact same (i.e. the above accessories DO NOT fit), but see Pomema Electronics part # 6491 - 6503, which are similar probes in terms of stabby sprining ends, but are much lower cost to buy separately.
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@OP
You may have been thinking about 'What's All This Copper-Clad Stuff, Anyhow?' p65 from 'The Best of Bob Pease' www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf (http://www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf)
There are several other books/collections of Bob Pease's work. e.g.
'A Tribute to Bob Pease - Troubleshooting Analog Circuits'
'Troubleshooting Analog Circuits - EDN Series for Design Engineers'
and a lot more, I'm sure.
It would be great if someone had a definitive list...
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I made a probe holder for my scope probe, and the scope probe tip is a fine-pitch spring-loaded tip so makes probing very easy. Here's an image (I forget why the background is removed, sorry it makes it looks like it's floating, I must have wanted to use this for something else):
Good idea.
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When I was still in the service trade, we'd simply tack-solder an offcut of component lead to the pad in question and use the usual hook ended clip on probe tips.
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That looks perfect..checking out the magnetic bases now.
A magnet-enabled test area for rf devices..is perfect for positioning all the parts of the signal chain and also grounding everything, reducing RFI.
I made a probe holder for my scope probe, and the scope probe tip is a fine-pitch spring-loaded tip so makes probing very easy. Here's an image (I forget why the background is removed, sorry it makes it looks like it's floating, I must have wanted to use this for something else):
(http://www.colinoflynn.com/oldsite/tiki-download_file.php?fileId=90&display)
I've got some details including a video here: http://colinoflynn.com/2014/01/making-a-simple-scope-probe-holder/ (http://colinoflynn.com/2014/01/making-a-simple-scope-probe-holder/) . The base is a 'magnetic base' which you can get at all sorts of places, and is available in various sizes. I've got some smaller ones now.
The probe itself is a PicoScope probe, but is available from most of the manufactures too under their own name. Here's a comparison to a normal scope probe tip:
(http://circuitcellar.com/wp-content/uploads/2014/02/Figure-4-web.jpg)
The probe is the same as these ones:
*PicoScope TA150 (350-MHz bandwidth)
*PicoScope TA133 (500-MHz bandwidth)
*Agilent N287xA
*Teledyne LeCroy PP007
*Rohde & Schwarz RTM-ZP10 (NB: this is very slightly different possibly, the others are clearly all made by the same manufacture though)
One nice feature of the above probes is they sell little caps which make it easier to probe QFP packages too:
(http://media.digikey.com/Photos/Teledyne%20LeCroy%20Photos/PK007-012.jpg)
So it's possible to vaguely hold the probe with one hand that way :) See for example Lecroy's accessory list (http://cdn.teledynelecroy.com/files/accessories/pp007_pp008_accessorydiagram.pdf), but again they are the same upstream supplier that is making all of them. There is also a nice ground blade that connects to a piece of copper tape you mount on the IC for your ground connection when using the caps.
It's not the exact same (i.e. the above accessories DO NOT fit), but see Pomema Electronics part # 6491 - 6503, which are similar probes in terms of stabby sprining ends, but are much lower cost to buy separately.
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Here are some more- Love his stuff..
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%209.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%209.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%208.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%208.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%207.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%207.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%205.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%205.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%204.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%204.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%203.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%203.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%201.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%201.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%206.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%206.pdf)
http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%202.pdf (http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%202.pdf)
@OP
You may have been thinking about 'What's All This Copper-Clad Stuff, Anyhow?' p65 from 'The Best of Bob Pease' www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf (http://www.ti.com/ww/en/bobpease/assets/www-national-com_rap.pdf)
There are several other books/collections of Bob Pease's work. e.g.
'A Tribute to Bob Pease - Troubleshooting Analog Circuits'
'Troubleshooting Analog Circuits - EDN Series for Design Engineers'
and a lot more, I'm sure.
It would be great if someone had a definitive list...
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Someone posted their Kickstarter campaign above but now you can buy whatever bits you need and DIY - http://pcbgrip.com/collections/fittings (http://pcbgrip.com/collections/fittings)
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I use the Rigol probe brackets. They came together with the probes of the DS6000 series.
The Rigol product number for the bracket only is RP5600A-0200701, I don't know the price.
I like them very much. It gets a little crowded when you want to use 3 or 4 probes on a QFP-64...
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So it's possible to vaguely hold the probe with one hand that way :) See for example Lecroy's accessory list (http://cdn.teledynelecroy.com/files/accessories/pp007_pp008_accessorydiagram.pdf), but again they are the same upstream supplier that is making all of them. There is also a nice ground blade that connects to a piece of copper tape you mount on the IC for your ground connection when using the caps.
I 3D printed something similar for my existing 150MHz probes, and the result is electrically better: no ringing at 100MHz. HP produced similar devices for "500MHz" probes. With low-impedance Z0 probes similar techniques are available for 1.5GHz probes. (I've just received a version in nylon from Shapeways, but haven't verified its performance yet, but see no reason that it would be any worse.)
See https://entertaininghacks.wordpress.com/2015/04/23/scope-probe-accessory-improves-signal-fidelity/ for more details.
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You can use those spring clamp things you get from the DIY store.
(http://i34.photobucket.com/albums/d123/photobucket391/P1000145_zpsbeohs1ev.jpg) (http://s34.photobucket.com/user/photobucket391/media/P1000145_zpsbeohs1ev.jpg.html)
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I am using a granite measurement table that has a quick adjustment arm installed.
This arm came with a holder for a micro gauge and one of the holes fitted perfectly for an Agilent scope probe.
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@howardlong I like that DIY probe holder of yours! I'll give that a try too.
This guy from Teledyne-Lecroy has the Jaguar of probe and work clamps, it has a micrometer adjustment to move the probe tip up and down to touch the work.
SPARQ Probe Deembedding Part 1 (https://www.youtube.com/watch?v=zvq1z2lA4wM#ws)
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One of the best methods for positioning arbitrary things is to use the liquid cooling "hose" from a lathe.
http://www.instructables.com/id/Third-Hand-A-multi-use-helping-hand-for-electro/ (http://www.instructables.com/id/Third-Hand-A-multi-use-helping-hand-for-electro/)
(http://cdn.instructables.com/FJC/0OH2/F7PCOX6T/FJC0OH2F7PCOX6T.MEDIUM.jpg)
They show attachments for oscilloscope probes and such if you read the tutorial.
(http://cdn.instructables.com/FWG/S9TB/F7PCOX7M/FWGS9TBF7PCOX7M.MEDIUM.jpg)
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t has a micrometer adjustment to move the probe tip up and down
While not a micrometer adjustment, the $15 magnetic-base dial holder I'm using has a knob (http://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html) that allow you to achieve the same goal of adjusting pressure/moving the tip down nicely:
(http://www.harborfreight.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_17902.jpg)
EDIT: The magnet part isn't used for me at least, as don't have a steel workstation! But the base is very heavy so all you need for holding a scope probe. Just keep it turned 'off' to make it more difficult to bring near your hard drive...
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One of the best methods for positioning arbitrary things is to use the liquid cooling "hose" from a lathe
I find these useless for precision work. Or at least the set I got from Sparkfun. They are super rigid so when once set you try and move them a milimeter, you push and push until it goes clank... and jumps half an inch. Tried lubricating and what not to no avail...
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The bast probe holder is the lab assistant. Since companies tend to be frugal, and dont spend money to get us help, technicians, lab assistants, secretaries and or even apprentices, we use other engineers to hold the probe. Even though they are kinda over qualified to do that. They also complain a lot more.
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That looks very professional. Those adjustable/articulated arms look ideal.
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Wouldn't it be simpler to just solder a small wire? Probably takes a lot less than trying to position some whacky probe holder.
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At the risk of self promotion, I wanted to share some ideas:
We built our own "probing pcb",build details found here: http://pcbgrip.com/blogs/blog/19160631-building-a-probing-pcb (http://pcbgrip.com/blogs/blog/19160631-building-a-probing-pcb). Basically building a simple PCB that connects pogo pins at your custom spacing location to a standard 0.1" header and you connect your test gear to the header. Custom probing PCBs could be built inexpensively to suit your own needs:
(http://cdn.shopify.com/s/files/1/0475/0653/files/Step_8_large.jpg?2789444799434035841)
In this picture you can also see a pogo pin (with head shrink) being held, with the test gear attached to the pogo.
If your looking to hold a probe, this is another option, which can be found here: http://pcbgrip.com/collections/fittings/products/probe-clamp (http://pcbgrip.com/collections/fittings/products/probe-clamp)
(http://cdn.shopify.com/s/files/1/0475/0653/products/20007_Probe_Clamp_Two_on_IC.jpg?v=1422139233)
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The PCBGRIP parts to do work nicely with small scope probes, a little fiddly to get into the right position sometimes but hold very well. If you use the stand you can even probe both sides of a board.
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At the risk of self promotion, I wanted to share some ideas:
...
Basically building a simple PCB that connects pogo pins at your custom spacing location to a standard 0.1" header and you connect your test gear to the header. Custom probing PCBs could be built inexpensively to suit your own needs:
Don't worry about promoting good ideas :) If push-comes-to-shove you can say something about "eating my own dogfood" or "believing in what I promote" :)
More seriously, how well does/doesn't it work with scope probes that don't have pogo pins?
Ditto, if you can't use a 6" ground lead because of its inductance, and have to use a probe plus its ground spring clip?
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At the risk of self promotion, I wanted to share some ideas:
...
Basically building a simple PCB that connects pogo pins at your custom spacing location to a standard 0.1" header and you connect your test gear to the header. Custom probing PCBs could be built inexpensively to suit your own needs:
Don't worry about promoting good ideas :) If push-comes-to-shove you can say something about "eating my own dogfood" or "believing in what I promote" :)
More seriously, how well does/doesn't it work with scope probes that don't have pogo pins?
Ditto, if you can't use a 6" ground lead because of its inductance, and have to use a probe plus its ground spring clip?
depends on your creativity with the set up. it's painfully configurable so your ability to visualize the solution is the only limit to what angles you can probe from.
I'm not the most spatially aware so it takes me a bit to get the perfect setup.
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At the risk of self promotion, I wanted to share some ideas:
...
Basically building a simple PCB that connects pogo pins at your custom spacing location to a standard 0.1" header and you connect your test gear to the header. Custom probing PCBs could be built inexpensively to suit your own needs:
Don't worry about promoting good ideas :) If push-comes-to-shove you can say something about "eating my own dogfood" or "believing in what I promote" :)
More seriously, how well does/doesn't it work with scope probes that don't have pogo pins?
Ditto, if you can't use a 6" ground lead because of its inductance, and have to use a probe plus its ground spring clip?
depends on your creativity with the set up. it's painfully configurable so your ability to visualize the solution is the only limit to what angles you can probe from.
I'm not the most spatially aware so it takes me a bit to get the perfect setup.
My question is more about whether a non-springloaded probe point (or two!) can be held against a pin/track. Pogo pins are undoubtedly more compliant in that respect. I'm sure I can adequately position the probe in an x-y plane, but the z-plane is more critical.
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At the risk of self promotion, I wanted to share some ideas:
...
Basically building a simple PCB that connects pogo pins at your custom spacing location to a standard 0.1" header and you connect your test gear to the header. Custom probing PCBs could be built inexpensively to suit your own needs:
Don't worry about promoting good ideas :) If push-comes-to-shove you can say something about "eating my own dogfood" or "believing in what I promote" :)
More seriously, how well does/doesn't it work with scope probes that don't have pogo pins?
Ditto, if you can't use a 6" ground lead because of its inductance, and have to use a probe plus its ground spring clip?
depends on your creativity with the set up. it's painfully configurable so your ability to visualize the solution is the only limit to what angles you can probe from.
I'm not the most spatially aware so it takes me a bit to get the perfect setup.
My question is more about whether a non-springloaded probe point (or two!) can be held against a pin/track. Pogo pins are undoubtedly more compliant in that respect. I'm sure I can adequately position the probe in an x-y plane, but the z-plane is more critical.
x-y is idiotproof, but getting the critical amount of z-axis stability is your problem. in general it's quite difficult to get it perfectly stable for me. I guess the question is how stable do you need it to be?
I can get my probing set up, but if you bump it, you'll need to restart.
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x-y is idiotproof, but getting the critical amount of z-axis stability is your problem. in general it's quite difficult to get it perfectly stable for me. I guess the question is how stable do you need it to be?
I can get my probing set up, but if you bump it, you'll need to restart.
Drat. But I'm not surprised.
I'm still looking for something better than http://i.stack.imgur.com/cbLXI.png (http://i.stack.imgur.com/cbLXI.png) or http://www.edn.com/ContentEETimes/Images/00PCB/cclad1f3.jpg (http://www.edn.com/ContentEETimes/Images/00PCB/cclad1f3.jpg)
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I get solid, stable readings when I have it set up.
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At the risk of self promotion, I wanted to share some ideas:
We built our own "probing pcb",build details found here: http://pcbgrip.com/blogs/blog/19160631-building-a-probing-pcb (http://pcbgrip.com/blogs/blog/19160631-building-a-probing-pcb). Basically building a simple PCB that connects pogo pins at your custom spacing location to a standard 0.1" header and you connect your test gear to the header. Custom probing PCBs could be built inexpensively to suit your own needs:
(http://cdn.shopify.com/s/files/1/0475/0653/files/Step_8_large.jpg?2789444799434035841)
In this picture you can also see a pogo pin (with head shrink) being held, with the test gear attached to the pogo.
If your looking to hold a probe, this is another option, which can be found here: http://pcbgrip.com/collections/fittings/products/probe-clamp (http://pcbgrip.com/collections/fittings/products/probe-clamp)
(http://cdn.shopify.com/s/files/1/0475/0653/products/20007_Probe_Clamp_Two_on_IC.jpg?v=1422139233)
Thanks for posting this. I have seen PCBGrip posted before but could not remember the name.
I have been tempted to buy one of these kits a couple of times now, but I've had two reservations:
1) The kit pages on your site, while showing all components quite neatly, don't really demonstrate the various ways you can configure all the parts. The pictures just look like a whole bunch of parts. It's not obvious to me which kit is appropriate, because I can't really see it in action. Some actual action pics of each kit would really help.
2) (and this is more personal/subjective) I wonder if I would actually use the kit in practice, or if it will be more work than it's worth/take up more space than is practical. I have lots of various panavise bases and tops and for the most part they cover my PCB-holding needs well. I also have a cheap Aven PCB holder ( http://www.amazon.com/Aven-17010-Adjustable-Circuit-Holder/dp/B00Q2TTQEE/ (http://www.amazon.com/Aven-17010-Adjustable-Circuit-Holder/dp/B00Q2TTQEE/) ), but I almost never use it because of how high it holds the board. The awesome anodized parts of PCBGrip appeal to my nerd-self, but I fear the setup would be much too fiddly and I would be constantly adjusting it.
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1) The kit pages on your site, while showing all components quite neatly, don't really demonstrate the various ways you can configure all the parts. The pictures just look like a whole bunch of parts. It's not obvious to me which kit is appropriate, because I can't really see it in action. Some actual action pics of each kit would really help.
Agreed, the kit pages how a lot of parts. For each of the kit pages, there is a table on the page that shows the name and quantity of each part included in the kit. If you click on the part name, it will take you to that individual part and show some pictures of the part in action. But, we still need to show more parts in action - something we will work on.
2) (and this is more personal/subjective) I wonder if I would actually use the kit in practice, or if it will be more work than it's worth/take up more space than is practical. I have lots of various panavise bases and tops and for the most part they cover my PCB-holding needs well. I also have a cheap Aven PCB holder ( http://www.amazon.com/Aven-17010-Adjustable-Circuit-Holder/dp/B00Q2TTQEE/ (http://www.amazon.com/Aven-17010-Adjustable-Circuit-Holder/dp/B00Q2TTQEE/) ), but I almost never use it because of how high it holds the board. The awesome anodized parts of PCBGrip appeal to my nerd-self, but I fear the setup would be much too fiddly and I would be constantly adjusting it.
When I started building PCBs, I was building custom jigs made of various parts, including wood and springs. I could not find a setup to hold the PCB and be able to hold other things too (like hold through hole components upside down while I soldered). PCBGRIP is great at holding the PCB and 'something else'. PCBGRIP uses a open source aluminium extrusion (OpenBeam), which accepts standard 3mm hardware. That way, it is easy to attach what every you need to your setup, it addition to holding the PCB. The hinge assembly allows you to rotate the PCB 360 degrees. The PCB can be tilted. Also, the height of work can be adjusted, by raising or lowering the hinge assembly on the 10mm stainless rod. Here is an overview of the work height that can be accomplished http://pcbgrip.com/blogs/blog/18208587-work-height-and-position (http://pcbgrip.com/blogs/blog/18208587-work-height-and-position). Here is a holder we designed to hold a Saleae logic analyzer, to give you an idea of how things can be attached to the OpenBeam:
(http://cdn.shopify.com/s/files/1/0475/0653/files/Saleae_3D_holder_L_78f644a9-dccc-4e9d-9750-8d31bf279d17_large.jpg?3142318269312892353)
The Saleae holder is available on Thingiverse here : http://www.thingiverse.com/thing:735911 (http://www.thingiverse.com/thing:735911)
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Wouldn't it be simpler to just solder a small wire? Probably takes a lot less than trying to position some whacky probe holder.
My colleagues do this with sometimes 10-15CM wires. Signal integrity is a magic world.
I prefer soldering a small, 1-2mm hook. Best is a 1K resistor to SMA, SMA cable, BNC adapter scope, 50Ohm. 1:20.
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Wouldn't it be simpler to just solder a small wire? Probably takes a lot less than trying to position some whacky probe holder.
My colleagues do this with sometimes 10-15CM wires. Signal integrity is a magic world.
I prefer soldering a small, 1-2mm hook. Best is a 1K resistor to SMA, SMA cable, BNC adapter scope, 50Ohm. 1:20.
Depends a lot on the frequency. For most things, a 1-3 cm wire will have no noticeable effect on the reading and you can easily connect with the oscilloscope probe to it. Slow digital signals are more forgiving and you can definitely get away with longer wires.
The SMA setup sounds interesting, but I'm having trouble imagining it, could you maybe post a picture?
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Also, if you are making the boards yourself it is wise to include ground plane on top so you can do the oscope ground spring trick.
You wind a spring around a drill blank the same diameter as your probes ground shield, then solder that spring to some ground plane exposed on the top of the PCB. The center of your spring should be where you want to probe, so you just stick a probe in it and everything is held in place nice.
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Also, if you are making the boards yourself it is wise to include ground plane on top so you can do the oscope ground spring trick.
You wind a spring around a drill blank the same diameter as your probes ground shield, then solder that spring to some ground plane exposed on the top of the PCB. The center of your spring should be where you want to probe, so you just stick a probe in it and everything is held in place nice.
There's also the very convenient commercial and homebrew techniques outlined in https://entertaininghacks.wordpress.com/2015/04/23/scope-probe-accessory-improves-signal-fidelity/
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I have just finished developing this great system for probing and injecting low power signals.
Quite cheap too.
https://www.ebay.ca/itm/High-Precision-Needle-PCB-Probing-System-Quick-Magnetic-Holders-Low-Profile/263447821265?autorefresh=true (https://www.ebay.ca/itm/High-Precision-Needle-PCB-Probing-System-Quick-Magnetic-Holders-Low-Profile/263447821265?autorefresh=true)
Norm
Cortex R&D Inc
Quebec, Canada
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I also collected all the small tip inserts for the Tek SMD probes which clumsy colleagues left wasted or simply lost and made pogo tip extensions and angular shifts out of them.
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I have just finished developing this great system for probing and injecting low power signals.
Quite cheap too.
https://www.ebay.ca/itm/High-Precision-Needle-PCB-Probing-System-Quick-Magnetic-Holders-Low-Profile/263447821265?autorefresh=true (https://www.ebay.ca/itm/High-Precision-Needle-PCB-Probing-System-Quick-Magnetic-Holders-Low-Profile/263447821265?autorefresh=true)
Norm
Cortex R&D Inc
Quebec, Canada
eBay says you don't ship to US, that right?
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Quote from: ivaylo on January 20, 2018, 06:41:19 PM (https://www.eevblog.com/forum/index.php?topic=46028.msg1405164#msg1405164)
>Quote from: Cortex on January 20, 2018, 07:56:15 AM (https://www.eevblog.com/forum/index.php?topic=46028.msg1404807#msg1404807)I have just finished developing this great system for probing and injecting low power signals.
Quite cheap too.
>https://www.ebay.ca/itm/High-Precision-Needle-PCB-Probing-System-Quick-Magnetic-Holders-Low-Profile/263447821265?autorefresh=true (https://www.ebay.ca/itm/High-Precision-Needle-PCB-Probing-System-Quick-Magnetic-Holders-Low-Profile/263447821265?autorefresh=true)
Norm
Cortex R&D Inc
Quebec, Canada
eBay says you don't ship to US, that right?
Yes, I do ship worldwide! I made a mistake, and I've changed my listing since.
But now, I sell it as a kit because it takes too much of my time to assemble all of them. But it's very easy and takes about an hour if you're not in a hurry.
BTW, I changed my design a bit, to include another thumb screw for the coarse boom vertical offset adjustment, and traded all Torx for more popular Philips screws.
* Also, if you want to bypass eBay, I can shave off about $5 CAD.
Email me directly if you're interested: nd@ctrnd.com
Norm
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One of the things I worry about is shorting pins when measuring live circuits, it's incredibly easy to do in some cases (particularly on dense ICs, trying to measure individual pins) and can result in unexpected damage.
What I do if I need to measure delicate electronics, particularly if high bandwidth isn't important, I take some 30AWG wrapping wire (https://www.amazon.com/gp/product/B00GWFECWO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B00GWFECWO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1)) And lightly solder the wire onto the test points I like to measure. I then hook my probes to the wrapping wire and turn on the device. This then gives me the full freedom of connecting as many DMMs (most of my DMMs have clip leads on them) as I want and as many scope probes I need.
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@cortex seems to have relisted his little probe kit for a bit less than $50 and it actually looks quite competitive compared to similar products, IMHO.
Cortex, have you ever considered using mini coax, and including a grounding connection for the metal plate? If I bought something like that I would either expect it to have a grounded shielded probe or I would modify it afterward to use shielded probe wire. I tried to build something similar using mini coax, it remains in a semi unfinished state, I need some more parts.
I was using old drafting tools as the source for my parts. They are very cheap considering what they originally sold for.
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One of the things I worry about is shorting pins when measuring live circuits, it's incredibly easy to do in some cases (particularly on dense ICs, trying to measure individual pins) and can result in unexpected damage.
What I do if I need to measure delicate electronics, particularly if high bandwidth isn't important, I take some 30AWG wrapping wire (https://www.amazon.com/gp/product/B00GWFECWO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B00GWFECWO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1)) And lightly solder the wire onto the test points I like to measure. I then hook my probes to the wrapping wire and turn on the device. This then gives me the full freedom of connecting as many DMMs (most of my DMMs have clip leads on them) as I want and as many scope probes I need.
I understand your concern. But when the needles are very sharp, this never happens because as soon as it touches the IC's lead, it bites right into the metal and won't slip. If you have the possiblilty to stick the needle in the softer solder, that's even better. In worst case, if you're really worried about shorting a critical circuit, you have the option of scraping off a bit of PCB enamel to uncover the trace of interest, and use that bare copper spot to probe the signal.
But as an example, I've been debugging a baud rate problem on a super small circuit, the VESD05A8A in the LLP1713-9L package, where pins are 0.2mm wide and 0.4mm apart! The probes did a marvelous job. Before that, I tried the scope probes, and I got that slipping+shorting problem all the time.
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@cortex seems to have relisted his little probe kit for a bit less than $50 and it actually looks quite competitive compared to similar products, IMHO.
Cortex, have you ever considered using mini coax, and including a grounding connection for the metal plate? If I bought something like that I would either expect it to have a grounded shielded probe or I would modify it afterward to use shielded probe wire. I tried to build something similar using mini coax, it remains in a semi unfinished state, I need some more parts.
I was using old drafting tools as the source for my parts. They are very cheap considering what they originally sold for.
Thanks! I think the quality/price ratio is hard to beat. I sure would love to mass produce them because right now, the profit margin is ridiculous.
About the coax idea, I must admit that I try to stay away from specialy items like this. The less parts the better.
The only other model I might create is an universal probe holder, so you will be able to position your fancy 500MHz+ probe precisely and directly on the PCB. The grounding challenge is left to you as usual, because it depends on each circuit's topology (where's the nearest ground) and the wire must be as short as possible.
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Does someone have experience with this probe holder https://youtu.be/FUY33geMrq0 (https://youtu.be/FUY33geMrq0)?
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Does someone have experience with this probe holder
Welcome to the forum, AntonLoeb.
Do you have any idea who makes it or where to get it?
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https://www.probeholder.com/ (https://www.probeholder.com/)
Swiss made, costs 98 CHF.
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Harbor Freight is your friend (or your regional equivalent): https://www.harborfreight.com/multi-position-magnetic-base-with-fine-adjustment-63663.html (https://www.harborfreight.com/multi-position-magnetic-base-with-fine-adjustment-63663.html)
John
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BTW, I changed my design a bit, to include another thumb screw for the coarse boom vertical offset adjustment, and traded all Torx for more popular Philips screws.
Any updated listings?
Also, pity about Torx — I think it’s the superior screw head for nearly all applications. I kinda wish Phillips would shrivel up and die. (Up in Canada you use Robertson screws a lot, right? So maybe you have fewer hateful experiences with Phillips. It doens’t help that many screws are actually PoziDriv, which works with a Phillips driver, but with even worse performance... and most people aren’t aware of PoziDriv so they don’t have the right drivers.)
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And Phillips is popular where? Masoland? :-// For big things Torx and small things hex. For example with power tools everything adjustable is hex, and everything you screw into things is Torx. My CNC was also all hex and for stuff I added to it also did choose hex. No failures.
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Wouldn't it be simpler to just solder a small wire? Probably takes a lot less than trying to position some whacky probe holder.
My colleagues do this with sometimes 10-15CM wires. Signal integrity is a magic world.
I prefer soldering a small, 1-2mm hook. Best is a 1K resistor to SMA, SMA cable, BNC adapter scope, 50Ohm. 1:20.
Do you happen to work for the same company as I do?
I've seen this "technique" (the long wires) way too often.
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Wouldn't it be simpler to just solder a small wire? Probably takes a lot less than trying to position some whacky probe holder.
My colleagues do this with sometimes 10-15CM wires. Signal integrity is a magic world.
I prefer soldering a small, 1-2mm hook. Best is a 1K resistor to SMA, SMA cable, BNC adapter scope, 50Ohm. 1:20.
Do you happen to work for the same company as I do?
I've seen this "technique" (the long wires) way too often.
... this would already make three of us! :-DD
seriously though, at least for the two of us, the chance we both work for the same enterprise isn't even that low...
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Wouldn't it be simpler to just solder a small wire? Probably takes a lot less than trying to position some whacky probe holder.
My colleagues do this with sometimes 10-15CM wires. Signal integrity is a magic world.
I prefer soldering a small, 1-2mm hook. Best is a 1K resistor to SMA, SMA cable, BNC adapter scope, 50Ohm. 1:20.
Do you happen to work for the same company as I do?
I've seen this "technique" (the long wires) way too often.
... this would already make three of us! :-DD
seriously though, at least for the two of us, the chance we both work for the same enterprise isn't even that low...
What else would you do ? ^-^
+ on both wire hook and 1k and 450 ohm resistors terminated into 50 ohm scope...
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I'm digging up an old thread rather than start a new one.
I like the Harbor Freight item (https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html (https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html)), but wondering if anyone has made a 3D holder?
My needs would be for various scope probes and meter leads, so I'd need something that can adapt to different lead types.
Recently I began repairing a board with 0402 components and need a spare hand. Something that would hold a probe lead and/or multi meter leads would be great.
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I'm digging up an old thread rather than start a new one.
I like the Harbor Freight item (https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html (https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html)), but wondering if anyone has made a 3D holder?
My needs would be for various scope probes and meter leads, so I'd need something that can adapt to different lead types.
Recently I began repairing a board with 0402 components and need a spare hand. Something that would hold a probe lead and/or multi meter leads would be great.
You might want to check out Noga arms (https://www.noga.com/Products/hold/Holding%20System (https://www.noga.com/Products/hold/Holding%20System)) (or one of the knockoffs). I haven't used mine to hold probes, but for getting dial indicators into strange positions quickly, they can't be beat.
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I didn’t see prices. Did I miss something? From looking at their products, I’d guess they aren’t cheap.
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I use these surgical locking clamp thingys. Cheap, universal and effective.
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;D :-+