Author Topic: Benefits of logic analyzer probe grabbers  (Read 1122 times)

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Offline newtekuserTopic starter

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Benefits of logic analyzer probe grabbers
« on: February 28, 2023, 01:39:52 am »
I've seen them used with bench top analyzers like the TLA but not with USB analyzers and was curiois to know if they add any benefit other than being able to grab onto SMD components. I.e. reduce capacitance like scope probes maybe

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Offline nctnico

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Re: Benefits of logic analyzer probe grabbers
« Reply #1 on: February 28, 2023, 01:11:22 pm »
If anything, the grabbers introduce more self inductance. But for many measurements it doesn't matter. Actually, I use logic analyser grabbers together with an oscilloscope probe regulary to get to signals in places where an oscilloscope probe is too large.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline thm_w

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Re: Benefits of logic analyzer probe grabbers
« Reply #2 on: March 01, 2023, 01:26:57 am »
Many USB analyzers include them. I guess its just the cheapo $10 LA's that don't due to cost reasons.
https://usd.saleae.com/products/saleae-logic-8

But there are usually better ones like the HP grabbers or these newer cheap ones are quite good: https://www.eevblog.com/forum/testgear/affordable-micro-grabbers/
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Offline james_s

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Re: Benefits of logic analyzer probe grabbers
« Reply #3 on: March 01, 2023, 01:54:22 am »
The reason you don't always see them is likely just about cost. The cheap ones are pretty crap too compared to stuff like HP. There is no one size fits all probe, it really depends on what you're trying to connect it to and how much space you have.
 

Offline alm

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Re: Benefits of logic analyzer probe grabbers
« Reply #4 on: March 01, 2023, 02:50:28 am »
I'd suggest getting the largest type that works for your application, purely for mechanical stability. The common mini-grabbers are great for DIP and decent for SOIC, but I wouldn't use them for anything with a finer pitch than SOIC. They are not so great for large components like TO-220 (possible ground connection). There are larger grabbers like mini grabbers for that, but they are not often used with logic analyzers. For smaller pitches there are smaller grabbers, but these are much more fragile. This page on the Sigrok wiki gives a decent overview. In my opinion it is worth paying for quality (e.g. EZ-Hook) over the cheap Aliexpress crap.

As far as signal integrity, any sort of extension introduces inductance and degrades signal integrity, but I'd expect bench top analyzers to be less sensitive due to their lower input capacitance because of the resistive divider near the tip and lossy cables they use, while USB analyzers usually have much more basic probes, like a bunch of unshielded "dupont" wires. But this is not generally the reason for the manufacturer to omit them, that will be purely a costs saving.


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