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1
Metrology / Re: USA Cal Club: Round 2
« Last post by SirAlucard on Today at 04:41:23 pm »
Awesome! I'm actually quite glad I'm near the end, for one I'll be moving soon like in the next month, so that'll be a pita. Secondly I'm looking forward to seeing everyone else's findings so that I can compare and check that my measly stuff are at least within ballpark. As I don't really have the fancy DMMs and equipment yet to do thorough testing. Looking forward to seeing everyone's results and keeping a sharp eye open for cheap equipment on the bay of evil.
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General Chat / Re: Aluminum etching
« Last post by generic_username on Today at 04:38:19 pm »
thank you but I was only generally interested how'd you contact aluminum etched products
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Open Source Hardware / Re: 4-wire short - DIY
« Last post by MiDi on Today at 04:37:18 pm »
Wow, that's a really nice idea, so one insert this and rotates it in position and tighten the binding posts screws, if I understand correctly. In case of a symmetrical grid, if you make it from metal it can be used as a Ninja throwing weapon  :-DD.

Well, if you can devise the PCB/plate shape correctly for Datrons as above (sadly I suck badly at mechanical design) you will have my gratitude and a beer & onion rings kit ;) at the local Eichbaum pub if you pass sometimes trough Mannheim  ^-^.
Of course I'm willing to measure whatever you instruct me to measure on the Datron panel, I have a digital Messchieber that collects dust ;).

Exactly, unscrew posts, put short in and rotate in position, screw posts.
At the moment it is just idea, has to be tested.
So first would do design for HP 3457A style posts and verify function.

There will be an option with sharp edges to throw like a ninja and an option to screw to your dremel to use as a saw  :-DD

Data needed: distances between posts, thickness of threads, thickness of insulation
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Projects, Designs, and Technical Stuff / Re: High impedance buffer
« Last post by BradC on Today at 04:33:24 pm »
Are you sure that the 4th pin on those 2N4117As is just the case, often the 4th pin on FETs is also substrate. Could ruin your day actively driving the substrate. Neither of the 2N4117 data sheets I have is explicit on the point, if I were you I'd want to get this confirmed or denied.

I might want to test that then. The interfet data sheet linked from the Mouser page I bought them from states "1-Source, 2-Drain, 3-Gate, 4- Case".
Never having looked at a JFet before and having 4 here on the desk, what would be a realistic way of measuring that without setting fire to a $15 FET?

Big resistor, say 1M, connect it to the suspected substrate. Ground the source, raise the suspected substrate (via the resistor, natch) to ~0.6V above ground and measure the current flow. If there is any, it's substrate, if there isn't it's just the case. On a 2N4117 it won't take much current to fry things, so don't omit that resistor.

Much appreciated. Used a 1M resistor. Pin 4 is connected to the case but there was absolutely no current between pin 4 and source. I double checked to make sure it was all good by swapping from the case to the gate, and got the expected Gate->Source current.

5
Test Equipment / Re: HP859x and external CRT
« Last post by RFDUK on Today at 04:31:38 pm »
I have the exact same SA and have been through the same search for a compatible monitor without success.

Has anyone used a monitor that is proven to be compatible?  Thanks.
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I thought PMSM meant that really it's the difference between the two that is the confusion.

So do off the shelf chips exist that take care of everything if I supply the power stage? well I know they do exist but is this something worth considering or is it a custom program on a micro controller?
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Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread
« Last post by bd139 on Today at 04:21:18 pm »
Has anyone actually tried measuring very low capacitance and inductance on these yet? I’m interested to see if you can zero off a fixture and then measure 200nH - 3uH effectively.
Also, I EFFING LOVE SMD.
How much ?
Really how much ? ?

If you're to properly embrace it you need SMD Smart Tweezers.............yes they can measure to 1nH too !
pF's, no problem.  :)

The set I bought 10+ years ago ceased the need to purchase a poultice of other equipment and I use them on everything. At the time the $ $ hurt but I've long since learnt good tools cost !


Being a pragmatist here but most of my SMD stuff (which I love more than I can explain)  is forward engineering so I don’t need to measure in circuit and can’t be bothered to test before I put it in. I buy decent quality brand name parts so I tend to assume that they are at least binned correctly. Virtually pointless testing in circuit as you’re testing the circuit not the component.

The thing I need the LCR meter for is mainly measuring inductors I’ve made, plus the odd old variable capacitor check (before I palm it off on eBay). I wind prolific amounts of toroids. I think I’ve done about 30 this month already.
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Let me take my seat.
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Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread
« Last post by Cerebus on Today at 04:17:17 pm »
Here is wisdom. Let him that hath
understanding count the number of the beast:
for it is the number of a page;
and his number is Six hundred threescore and six.
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Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread
« Last post by Cerebus on Today at 04:16:16 pm »
Waiting...

...for someone to beat me to the first post on page 666, and they didn't!
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