micrograbber to scope - Page 1
Forum section: electronics / testgear

author: electrolust
author_rank: Unknown
timestamp: November 17, 2016, 05:48:12 pm
content: How do folks normally connect a micrograbber to a scope? I can find only a couple of examples of probe to micrograbber adapters, and wow expensive. $65 for Pomona 6553.

author: Someone
author_rank: Super Contributor
timestamp: November 17, 2016, 10:11:48 pm
content: They came as accessories with the HP/Agilent 116x series of probes. Its better value to buy accessories with the probe, but I don't know of any current probes that include the accessory.More commonly you use a direct coax to grabbers (or pin headers) cable.

author: electrolust
author_rank: Unknown
timestamp: November 17, 2016, 11:27:49 pm
content: I thought the probe itself provided much of the electrical characteristics (impedance, capacitance) required to monitor signals. At least for the signals one might need a micrograbber to acquire.http://www.radio-electronics.com/info/t_and_m/oscilloscope/oscilloscope-probes.phpSo then a direct coax adapter would defeat this.

author: Someone
author_rank: Super Contributor
timestamp: November 18, 2016, 12:07:03 am
content: Pomona have a nice discussion on the matter:http://pomonaelectronics.com/index.php?i=a_scope_probePassive 10x probes can have a higher frequency response than direct coax but it depends on the impedance of what you are measuring, and for lower frequency signals where you might be considering the flying leads of a grabber then there can be little difference.Looking through the Agilent catalog to find the part number for that cute little SMD grabber pictured above (1400-3652) its not great value but very handy. But they (did?) sell cheap probe to flying pins adaptors N4826A and N4836A (might fit other 2.5mm probes) if you can track any of those down.

author: tautech
author_rank: Super Contributor
timestamp: November 18, 2016, 02:27:15 am
content: Don't normally bother with anything too fancy.A header arrangement I built years ago but only with the POS grabbers you can get for a dime a dozen from eBay.I used a 10mm strip of commercial switchboard and recessed loops into holes, designed to be grabbed with a probe hook.When I need something a little better out come the Tek grabbers.The Teks come with a square 0.025" pin and to connect to them you need to have a look in your junk pile for these push-on 0.025" tails or get some new crimp-on ones from your supplier. Form a soldered ring for the probe hook to connect to and Bob's your uncle.

author: electrolust
author_rank: Unknown
timestamp: November 18, 2016, 09:15:44 am
content: nice

author: georges80
author_rank: Frequent Contributor
timestamp: November 18, 2016, 05:50:24 pm
content: If you have the bnc adapter available for your scope probes then you can make your own easily for a couple of $.Here's an example that I made for one of my Agilent scope probes:https://www.eevblog.com/forum/testgear/o'scope-probe-adapter-where-from/msg623839/#msg623839Then the flying ends will fit on a standard header pin, on your board directly or to tek/agilent/generic micro grabbers.cheers,george.

author: electrolust
author_rank: Unknown
timestamp: November 25, 2016, 08:56:29 am
content: wow. what a very odd and satisfying coincidence. I was about to say, thanks anyway for the post but my scope did not come with a probe to BNC adapter. However when I saw the picture I realized something.Just yesterday I was cleaning up some odds and ends and organized a small collection of BNC adapters, attenuators, terminators and so on. There was one adapter I couldn't recognize. I thought it might be male to female without locking tabs on the female side, but nope a male end would not fit. I just separated it and put it back in the drawer.After seeing your post I realize now it is in fact a probe tip adapter! yes!!!Had you posted just 2 days ago, or maybe a week from now, I would not have made the connection. So the incredible timing of your post and my holiday cleanup is oh so fortunate for me.

author: tautech
author_rank: Super Contributor
timestamp: November 25, 2016, 09:15:00 am
content: Quote from: electrolust on November 25, 2016, 08:56:29 amYep, they may just look like some weird POS, not worth a second glance....until you need one.Trick is to know where you have it stashed, then it's gold not some POS.Keep all your probe bags and the derating charts, coloured rings, Gnd springs, adjustment tools AND probe to BNC adaptors together, then you'll know where to find them. Some old scopes were great as they had apaddedprobe and cable bag fixed to the chassis. I've got an old HP probe bag that keeps all my goodies together and safe.

author: nfmax
author_rank: Super Contributor
timestamp: November 25, 2016, 09:26:06 am
content: Keysight do just such an adapter as an accessory for their probes, and (surprisingly) the N4826A adapter for their 'low end' probe series is quite reasonably priced (or at least it was when I bought a set of 4!)http://www.keysight.com/en/pd-2427487-pn-N4826A/dual-lead-adaptor?nid=-32595.1096661&cc=GB&lc=eng

author: tggzzz
author_rank: Super Contributor
timestamp: November 25, 2016, 09:40:56 am
content: Don't forget that 1mm of wire = 0.8nH, and that will resonate with the tip capactance. A standard *10 high impedance probe with a 6" ground lead resonates at about 100MHz.If you need to avoid being "distracted" by such resonant ringing, you have to either reduce the capacitance or reduce the inductance, and reduce the resistance. One homebrew method is shown inhttp://koti.kapsi.fi/jahonen/Electronics/DIY%201k%20probe/and there are others referred to athttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/