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little test board Z518 (2023 Update)

We're building a box that processes an arbitrary waveform from a Tek AWG5000 box. Tek was kind enough to loan one to us for a couple weeks; it costs over $200K. The rep was great and helped me carry it down the stairs and bought me some bread at Tartine.

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We need a test signal for production test and won't use a Tek. This little board is sort of glue logic for the test setup and makes a sort of arbitrary waveform. And our 11801 sampling scopes need a pretrigger.

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Again, these little LVDS line receivers rock.

Reply to
jlarkin
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(re-post) Interesting, yeah, I checked their datasheet. These SN65LVDS_ parts have many nice features.

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but you noticed they have 300K pull-up resistors on the inputs? (Figure 16 in the d-sheet.) So your +2V rail may not be "stiff" enough to lock it in at +2V.

cheers, RS

Reply to
Rich S

The +2 divider source impedance is around 160 ohms, so it should be OK. But good point.

The timings don't need to be super precise (they won't be), just fairly stable.

Most scopes are mediocre or downright terrible for measuring time from an external trigger to a vertical channel. Most modern digital scopes quantize an external trigger to one sampling clock interval, and add extra drift too. The best way to measure delta-t or jitter is vertical channel-to-channel.

A dual-channel sampling head, like an SD-24, should sample both channels simultaneously. There is one sample pulse generator and two traveling-wave diode signal samplers:

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So if we interface a sampling scope and external trigger and then extract two lists of samples, we should be able to do math on that data and get stable, super-low jitter measurement regardless of trigger errors. I think.

Reply to
jlarkin

What an odd looking instrument. Can you pop the hood for some photos or do they have seals all over it? It looks like a project case with a tablet double sided taped into the window, with a power supply keypad and someshop made special binding posts.

Did you go looting last week?

Have any of your board/designs turned up on alibaba yet?

Reply to
Cydrome Leader

It's a pretty serious rackmount instrument. It looks really well engineered in real life. I wanted to open it up but figured it would be imprudent, especially since Tek has been so friendly.

The back is wild:

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One side is all air intake and the other is all fans. It kept my office cozy.

I was curious about the little thing on the upper-right of the front panel, with the two big screws. It's a hard drive.

???

No. Our stuff doesn't copy well into low-margin, high-volume junk.

Reply to
jlarkin

Looks like J7 is wired up wrong, no?

Cheers

Phil Hobbs

Reply to
Phil Hobbs

Wow, yeah, the back is where the action is. I'm trying to figure out how the 'puter board is installed in there so close to the power supply. The VGA out and eSATA are a knock out combination.

Everything is free in SF these days, I saw it on TV. Looks like some sort of smash, grab 'n go type holiday sale.

Do you ever post intentionally broken schematics on the internet, for fun?

Reply to
Cydrome Leader

Oh yeah, that. We all carry hammers in our shopping bags.

We are trend setters. Copycat gangs are looting all over the country now.

No. Schematics are sacred. But goofy schematics are OK.

Reply to
jlarkin

Good point. We should ground both lower pins. The Brat did this from my very rough sketch.

The barrel will ground through the box... when it's in the box.

Reply to
jlarkin

That one has bitten us too. Fortunately the rework is easy and invisible. ;)

Cheers

Phil Hobbs

Reply to
Phil Hobbs

The hardware equivalent of "it's just a test and a branch."

Reply to
jlarkin

The John Doe troll stated the following in message-id <sdhn7c$pkp$ snipped-for-privacy@dont-email.me:

And the John Doe troll stated the following in message-id <sg3kr7$qt5$ snipped-for-privacy@dont-email.me:

And yet, the clueless John Doe troll has itself posted yet another incorrectly formatted USENET posting on Wed, 1 Dec 2021 15:40:30 -0000 (UTC) in message-id <so851d$hk4$ snipped-for-privacy@dont-email.me.

This posting is a public service announcement for any google groups readers who happen by to point out that the John Doe troll does not even follow it's own rules that it uses to troll other posters.

VIdotl6l8rbq

Reply to
Edward Hernandez

The John Doe troll stated the following in message-id <sdhn7c$pkp$ snipped-for-privacy@dont-email.me:

And the John Doe troll stated the following in message-id <sg3kr7$qt5$ snipped-for-privacy@dont-email.me:

And yet, the clueless John Doe troll has itself posted yet another incorrectly formatted USENET posting on Thu, 2 Dec 2021 05:01:11 -0000 (UTC) in message-id <so9jum$ve9$ snipped-for-privacy@dont-email.me.

This posting is a public service announcement for any google groups readers who happen by to point out that the John Doe troll does not even follow it's own rules that it uses to troll other posters.

GPnMA84bw4R9

Reply to
Edward Hernandez

Why don't you old hens take your ritual clucking somewhere else?

Buy a battery and some LEDs and learn something.

Reply to
John Larkin

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