Divergence meter

Tari · Posted: 04 Jan 2012 05:04:21 pm Post subject: Divergence meter

I've mentioned this project a bit on IRC, but I figured it's finally a reasonable time to announce it more formally.

Project page

To summarize: this is a 8-digit nixie tube display. It serves more of a purpose in the fiction it comes from (outlined in more detail on the project page), but those functions are only useful as eye-candy IRL. The obvious option for something useful to do with this is build clock functionality into it, but the design includes capability for external communication so I can conceivably display any sort of numbers on it.

I've got most of the parts in-hand now (my PCBs should be waiting in the mailbox when I get back to school), so construction and testing will be proceeding as I am able to claim a lab bench somewhere and get soldering.

With that, I turn the conversation over to everyone else. Have some idea for interesting things I could make it do? Just want to express your similar appreciation of Steins;Gate? Sound off!
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graphmastur · Power User Joined: 27 Jul 2010 Posts: 464

First things first. I love you and Steins;gate.

Second, will you make/sell one for/to me?

Third. Wooot! Awesomeness!

Tari · Posted: 04 Jan 2012 05:13:39 pm Post subject:

DShiznit · Posted: 05 Jan 2012 11:59:33 am Post subject:

This looks awesome to me, mainly because it looks like something out of Fallout or similar art-deco science-fiction. I have no idea what Steins;gate is but now I might be interested.

darkmagicion2904 · Newbie Joined: 27 Apr 2012 Posts: 1

If you finish it ill buy it from you. or at least a reprogrammed board. would pay 150 to 200 for it. 0x5

KermMartian · Posted: 27 Apr 2012 08:27:22 am Post subject:

JoeYoung · Advanced Member Joined: 18 Dec 2008 Posts: 278

KermMartian · Posted: 27 Apr 2012 09:15:43 am Post subject:

Tari · Posted: 27 Apr 2012 09:53:24 am Post subject:

I know I get plenty of hits for the terms used here on my web site, a bit unusual that someone would find it here. Smile

While I'm here, a short status update:
I had to build a rev 1.1 board since some pin assignments on my microcontroller were insufficient for my needs, and it took about a month to get those board back from the fab.

After assembling the power supplies it mostly works, but my 3.3V micro can't drive the boost converter's FET hard enough to pull it fully on, so I need to rig up a FET driver to bridge my 9V and 3.3V rails. Driving it from a function generator I was able to get stable 190V output on the Nixie drive rail.
I ordered some ICL7667 samples from Intersil which haven't arrived yet, but I may end up hacking something together with an op-amp to get a similar effect. The op-amp solution may not be fast enough (I need to switch the FET at 64 kHz), but we'll find out
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KermMartian · Posted: 27 Apr 2012 10:25:50 am Post subject:

I'll be disappointed if some decent op-amps can't switch at 64 or 128 kHz. Sad

I'm of course glad to hear that you're still working on this. Did you end up using the same PCB fab that I used for my Clove 3 boards?
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Tari · Posted: 27 Apr 2012 01:34:21 pm Post subject:

KermMartian · Posted: 27 Apr 2012 01:56:19 pm Post subject:

Yup, the tell-tale purple color gives it away. I should probably figure out what I'm going to need boards of soon since as you pointed out it takes quite a while for the boards to arrive. Do you think it can handle traces fine enough for a BGA package like the AM335x, or not so much? Let me not get this too far off-topic, though.
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Tari · Posted: 27 Apr 2012 02:03:02 pm Post subject:

You get 6mil spacing on these, and a fairly small minimum drill, but I don't think it's small enough for a BGA, even if it has fairly large ball pitch like these devices do.

.8mm spacing on an 18x18 grid is going to be pretty tight (and expensive) on anything but very large scales, unfortunately. You'd probably need at least 4 layers to escape all the signals you need from around the chip.

I don't know offhand if TI have any similar chips with package-on-package options, but that might be worthwhile if only to reduce the number of signals you need to deal with on the board (and avoid routing high-speed buses, for that matter).
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elle · Newbie Joined: 01 Jun 2012 Posts: 1

Hi! Can I ask for the schematic design of your project? Where do you order PCBs?

Tari · Posted: 01 Jun 2012 05:40:03 pm Post subject:

Got the boards made through what is now OSH Park, who I believe get the panels made though Advanced Circuits.

The schematics and source code for my design are all in the Bitbucket repository. I went ahead and make an image of the schematic, although this revision of the schematic is known not-working: http://www.taricorp.net/2012/a-divergence-meter-note
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rajesh kumar · Newbie Joined: 01 Jun 2012 Posts: 1

Hi you have check capability of your PCB Fabricator.

They must some mini spacing/line width and other requirement.

4mil spacing/line width is easily doable.