Archive for October, 2008

Cort’s New RF Wattmeter

Monday, October 13th, 2008

Cort’s troubleshooting a new repeater installation out by Lecompton and sent me this picture of his adorable new RF wattmeter. (For the record, Cort calls it “old school” rather than “adorable,” but what does he know.)

Telewave RF wattmeter

He bought it from the Chuck Martin RF Shop, which he highly recommends.

Rackmount Stuff from Slim’s “Dump”

Monday, October 13th, 2008

Here’s the first batch of stuff from Slim’s “Dump” — rackmount equipment that I can’t identify as being associated with anything else from out there.

Rackmount stuff from Slim's dump

I can’t tell that any of this stuff as still useful (which presumably has something to do with why it was out in the Dump in the first place), so it’s destined for disassembly, component removal, case reuse, and recycling. If there’s anything that strikes you as useful, throw a comment down below about what it’s good for, offer to pay me what it’s worth to you plus shipping costs, and I bet we can work something out. I’d love to see some of it go to someone who’d actually make use of it.


Vibratory Tumbler for Cleaning Parts

Sunday, October 12th, 2008

A few weeks ago, I bought a “vibratory tumbler” at Harbor Freight for $40. I’ve been wanting one for quite a while — it seems like a good way to de-paint Altoids tins / clean old car parts / faux age woodcarvings / whatever.

Vibratory tumbler from Harbor Freight

You fill it 2/3 of the way with grit, throw crud-covered stuff into it, run it for a few hours, and out comes a shiny new pony! Or so goes the theory.

I wasn’t sure whether the Harbor Freight package included the requisite grit, so I didn’t buy any. It wasn’t included, so today I experimented with common household materials.

Conclusion: Kitty litter, no matter how hard the little gravels may feel underfoot in the morning, is way too soft. Driveway sand is extremely dusty and too smooth and/or large. Real grit or polishing compound is in my future.

Even so, the results were promising. Trey in Chicago asked for a few SO-239 jacks from Slim’s distribution cabinet, and they were pretty oxidized and seemed like a good opportunity to try the tumbler.

Oxidized SO-239 jacks

After a few hours of polishing:

Cleaned SO-239 jacks

Not bad.

(Ancient) Disk Drive Heads

Monday, October 6th, 2008

Lawrence’s son Jacob has been cleaning out their basement, and recently dismantled a TI disk drive about half the size of a washing machine — the kind where you load big cylindrical disk packs down into the center. They gave me a bunch of circuits from it to recycle, and I was intrigued by the disk heads.

TI disk drive heads

I grabbed them at first for the .1″ header connectors, and I was tickled by the spring armor around the wires, and then I decided I just liked the whole things.

TI disk drive heads, closeup

Enough to take a few pictures, anyway. But now I think it’s time to keep the wiring harnesses and ditch the rest.

Heh — if I got TGIMBOEJ, I’d throw some of these in. :-)

Cleaning Out Slim’s Dump

Sunday, October 5th, 2008

My friend Slim passed away about fifteen months ago, and this weekend Lawrence and I went out to Pittsburg to clean out Slim’s “Dump,” a storage unit on which Maeve had faithfully been paying rent (bless her heart) until Cort and/or I could come back and empty it.

Slim's storage unit upon arrival

It doesn’t look like much from this view, but there were four grocery-store shelving fixtures and several additional shelves full of miscellaneous old electronics and miscellaneous other things. With the shelves broken down into flat pieces, the contents completely filled Lawrence’s 15-passenger van, floor to ceiling, with all the seats removed.

Here’s the back corner after all the shelves and most of the storage contents had already been removed. There was a fair bit of Southwest Technical Products equipment back there, which is of no particular interest to me but considerable interest to a couple of other people I’m in contact with. I’ll be going through all the cases and boards, sorting into SWTPC versus other stuff, and cataloging and photographing the items for a separate post.

Back corner of Slim's storage after breaking down and removing main shelves

There were several coils of what I believe Cort referred to as aluminum hard line antenna cable, which he also said is outdated and of no further use. Lawrence will take drop it off for scrap metal recycling next weekend unless by some miracle someone indicates they think it’s still worth something before then.

Coils of hard line antenna cable

This TI Silent 700 hardcopy terminal with the dual cassette drives on top really tickles me. This DigiBarn post suggests they could upload and download content over the terminal line. I learned to program on teletypewriters on a timesharing system, and I have a soft spot for hardcopy terminals. The cassette drives are definitely icing on the cake. And I think I have about a dozen more of those drives, loose, from Slim.

Texas Instruments Silent 700 hardcopy terminal with tape drives

The “silent” in the name refers to the thermal paper, by the way, and I’m not sure I like the idea. Using a hardcopy terminal wouldn’t really be the same without the distinctive clatter of the DECWriter pins against the flat metal platen, and the almost anthropomorphic sound of the printhead sliding slightly to the right, to get out of your way and let you see what had just been typed, each time the terminal was idle for a couple of seconds.

Mission accomplished. Just a few non-electronics items left for Maeve to deal with.

Slim's storage, empty

Back home and unloaded, here’s what appears to be a campus A/V distribution patch cabinet. It has what I think are SO-239 connectors on the top (I’m not a radio guy) and 1/4″ sockets on the bottom. I’d be happy to part with the SO-239 panels if someone had a use for them.

AV distribution rack from Slim, front

Although it looks messy now because whoever uninstalled it did so rapidly, the cables were very nicely routed and carefully bundled and laced with waxed string, an art that I fear has become lost.

AV distribution rack from Slim, rear

Finally for today, my first treasure of this trip: an HP 122AR rackmount oscilloscope. Just last week, I was talking to Jeremy about installing a power inverter in my cargo van and setting up a gig box with a rackmount scope and some other tools for portable/mobile electronics troubleshooing and repair. If this works and it’s not too dep, it’ll be lovely for that! (Of course, I’ll have to make it clear that the gig box needs to be treated with care and not dropped out of the side of the van, but I think I can handle that.)

HP 122AR rackmount oscilloscope

Looks like it has two channels, which is cool. For this application I’d be even more excited if it had two axes (great for troubleshooting vector arcade games, and I do have a couple of two-axis scopes already, just not rackmount), but I’m thrilled with what I got.

Now I need a few sunny evenings or Saturdays to photograph and catalog the rest of what we brought back. There’s a lot of stuff that looks no longer useful to me, and I’ll be willing to work something out to get it into the hands of the right people if it’s still useful to someone else, so I hope to post good pictures and descriptions in the coming weeks.

Weird Stuff from Work

Friday, October 3rd, 2008

The Operations group at work is cleaning house, and they’re finding some odd things tucked away.

Multi-line phone breakout

Amphenol connector (male on one side, female on the other), an RJ-11 jack with two wires pinned, and a five-position (plus off) rotary switch. I’m assuming this went inline between a 25-pair cable and a key system telephone, to attach an answering machine to a line of your choice.

Real nice metal box, rotary switch, and lovely clunky knob.

And then this pretty much speaks for itself:

Wire splint box, front cover

Wire splint box, back cover

Wire splint

The wire mesh looks like it was dipped through a solder bath to hold it together.

Let’s just say I hope I’m never in a mine and get a fractured arm.

Fixed a USB Thumb Drive (Sort Of)

Friday, October 3rd, 2008

USB thumb drive, repaired

A couple of weeks ago, Matt from the desktop support group at work asked me for soldering advice / demonstration. Someone he supports kept all her data on a USB thumb drive with no backup, and it stopped working. When he opened it, he found the crystal had come off the board, and he wondered whether I could solder wires to it well enough to get the drive working and retrieve the data before discarding the drive.

It turns out the crystal was a through-hole design that had had its legs crimped into flat strips, then bent out sideways to surface-mount. (You can see the pads where it was originally mounted.) But that created stress points at the end of the crimped area where the leads were bent, and the owner treated the drive roughly enough (I think attached to her keychain that she dropped onto the counter every night) that both legs sheared clear off.

Didn’t leave me much to solder to, either, but I got it done. Matt’s too young to know wire wrap and didn’t have any on hand, but I found some stranded wire and used a single strand. It wasn’t an elegant job, but it was sturdy enough to survive some handling, and it actually worked. In spite of his professed faith in my abilities, Matt was amazed and delighted when he plugged in the drive and the contents popped right up on his computer.

And I get to keep the repaired drive as my reward. Which naturally means that I’ve already broken one of the wires. :-)

Puck is Stale But Not Forgotten

Friday, October 3rd, 2008

Wednesday over lunch, my brother sent me to Lustercraft Plastics to pick up a window well cover to replace one that got broken at a customer’s house.

And wow, their showroom is droolicious. Lots of sample tiles of different types, transclucencies, colors, and textures of plastic. Plastic dowels so dense they might as well have been cudgels. Flipchart-style collections of crazy bright colors of what felt like UHMW plastics. Really cool stuff. I need to go back and take my camera (with their permission) to get pictures of all the goodies.

Near the counter, they had a few trinkets, including a truncated cube (hm, maybe actually a rhombicuboctahedron) made of a clear plastic that still had a few deep milling gouges but was otherwise very well polished. I was impressed with how well it had shined up after cutting, so I asked what kind of plastic it was — and it turns out it was acrylic, aka plexiglas.

And they have cutoff scraps in the back, sold by the pound.

18mm and 25mm acrylic scraps

These 18mm and 25mm scraps of clear acrylic (underneath the paper covers) look to be good for milling puck cases, don’tcha think?

The puck project got stalled because I’m fussing over power issues — doing proper USB negotiation for 500mA (everyone assumes you can just grab as much as you want, but it’s a violation to take more than 100mA without asking), doing proper Li-Ion charge management (don’t want to cause the battery to vent with flame), and doing full-fledged power management (mediating among an external power source, a battery that can source current when needed or sink current when charging, and an LED load that has the potential to sometimes be higher than the 500mA max USB current).

But I have samples of parts for all those things, and the project isn’t dead yet. It’s just pining for the fjords.