The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Month: October 2012

Sienna Anti-Theft Blinky Light

Our Toyota Sienna arrived with a blank cover plate where a fancier model would have a switch. It seemed a shame to let that space go to waste, so I popped the plate out, rummaged around in the heap, found a small circuit board with a blinky LED that just exactly fit the space available, and drilled a suitable hole:

Sienna anti-theft blinker – inside

When it’s installed in the van, it looks and acts just like the security system we don’t have. For all I know, that plate was for the security system control, so perhaps it’s an exact match!

Sienna anti-theft blinker – bezel

The batteries last about two years, a few months later I notice the lack of blinkiness (it’s hidden behind the steering wheel in my normal driving position), and eventually I replace the corroded batteries. This time, I had to replace the entire battery holder; things got pretty nasty in there.

As I recall, the PCB came from a fancy “greeting card” mailed to me by the Business Software Alliance, with the implied threat that if all my paperwork wasn’t up to par, my use of potentially unlicensed software would blow up in my face. That was back in the day when mailing something that pretended to be a bomb was considered a cute joke and when I actually ran more than one Windows PC.

Linux is a lot more relaxing…

2012-10-10
Utility Knife Blade: Corrosion Thereof

This little utility knife lives in my belt pack for those occasions when I need a sharper blade than my long-suffering Swiss Army Knife can provide. Alas, I must have sliced up something awful in the recent past:

Corroded mini utility knife blade

Although the knife frame is slightly magnetic, it’s also reasonably noncorrosive and cleaned up pretty well after some Topsaver and wire-wheel brushing activity:

Mini utility knife – somewhat cleaned

Whew!

For whatever it’s worth, this is the same knife that made it through the Washington DC “security scans” that eventually confiscated Mary’s Swiss Army Knife. She didn’t look any more guilty than I did…

2012-10-09
Sprinkler System Plumbing

This Christmas Tree tops the fire sprinkler system in the Wentworth by the Sea hotel in New Castle NH:

Fire sprinkler system plumbing

The long pipe leading around the corner to the left-front riser drains the test valve. The honkin’ big supply pipe stands to the rear of the regulators and valves. You can’t quite see it from here, but those water pressure gauges showed about 180 psi.

The bathroom fixtures had the usual pressure and instant hot water, so there’s complex plumbing inside the walls, too.

Some equipment, you hope just never get used…

2012-10-08
Unusual Brick Corner

An old mill building built along a New Hampshire river had a pair of walls meeting at an acute angle:

Acute-angle brick corner

Architects know that bricks, being the prototypical rectangular solid, generally don’t work well in such situations, but I suppose sometimes you just do what must be done and call it decorative:

Acute-angle brick corner – detail

That steel post certainly took a direct hit at some point in its career, though…

2012-10-07
Beware the Lurking Lorem Ipsum

Fusion Hotspot Scrach-off Card

One of the motels we stayed at had a new (to me, at least) approach to the ubiquitous Free WiFi offering, which involved a small card with scratch-off fields:

Being the curious sort, I checked their website to see what they were up to. The main heading, across the top of the page, read:

Bringing wireless Internet capabilities to your property

Visus, in vut eu in auctor mus sit odio ac habitasse non! Vut et ac ultricies urna, mauris enim magna mus ac urna arcu, etiam vel,

Huh.

The rest of the page has Lorem ipsum filler under every heading, including:

24/7 Support

Tincidunt ultricies magnis adipiscing. Natoque, augue mattis pid placerat mattis pellentesque adipiscing dis, habitasse scelerisque aliquet, ultricies lundium, lectus cras mus, sit? Magna turpis duis placerat massa in integer porta, sit, phasellus, nec, elementum, scelerisque in?
Read More

Clicking that attractive Read More link produces pretty much what you’d expect by now:

Error 404 – Page not found!

The page you trying to reach does not exist, or has been moved. Please use the menus or the search box to find what you are looking for.

All the other links behaved the same way, including the Support header.

Oddly, the Contact Us item hidden in the About us pulldown produced a form, so I sent off a message. Haven’t gotten anything back yet and really don’t expect to, either.

It does give one pause to consider what happens to the bitstream between one’s tablet and the website. I make it a practice to not sign in to vital accounts while traveling…

At least they didn’t use the Samuel L. Jackson slipsum generator…

2012-10-06
Wouxun PTT Voltage Limit
TinyTrak3+ D6 – SMD Schottky diode

It seems that Wouxun KG-UV3D HTs require nearly 0 V to activate the PTT input, which I discovered after the radio on Mary’s bike began acting intermittently. The TinyTrak3+ would transmit correctly, but the PTT button on the handlebar began to not work at all / work intermittently / work perfectly. The switch and cable were OK, pushing the button produced nearly 0 Ω at the 3.5 mm plug, the connections seemed solid, but the radio didn’t transmit reliably.

I finally got the thing to fail on the bench, which led to the discovery that:
- Shorting the PTT input to the GPS+voice adapter PCB to ground didn’t make the radio transmit and
- Data bursts from the TinyTrack3 worked perfectly
Gotcha!

TT3 PTT In-Out

The TT3+ pulls its PTT OUT pin down from +5 V using a 2N2222A NPN transistor (off to the right in the schematic snippet), but, for reasons having to do with ESD, the input from the PTT switch on the handlebars goes through a 100 Ω series resistor, then passes to the TT3 board through PTT IN to D6 before joining the TT3 transistor collector. The low-active diode-ORed signal heads off through PTT OUT to a 10 Ω series resistor, thence to the KG-UV3D PTT input. D6 is an ordinary 1N4148, with the net result that the PTT input voltage at the radio dropped to 630 mV with the PTT button pressed.

Not finding anything else wrong, I replaced D6 with a BAT54 Schottky diode that pulled the PTT voltage down to 300 mV and the radio worked fine.

Of course, a BAT54 is a surface-mount diode, so I clipped off the unused no-connect lead (it’s the only way to be sure it doesn’t do anything) and tacked it down slaunchwise between the PCB thru-hole pads. If I had a BAT54C with common cathodes, I could replace both D5 and D6 in one shot, but D5 just pulls down a PIC input that has an ordinary logic-level threshold voltage.

I don’t know why the KG-UV3D PTT is so fussy, although it may really be a current-driven signal that requires more current than can flow through the 110 Ω + diode forward drop in series with the PTT button. Wouxun presents no specifications that I can find.

The identical circuitry on my bike works fine with the stock D6 diode and a presumably identical KG-UV3D. I should replace that diode before it gives me any trouble, but I’ll wait until I must take the box apart for some other reason.
2012-10-05
Vise Handle Bumpers

Bench vises (not vices) have heavy steel handles that clank when the ball end slams into the hub. You can fix that by slipping suitable rubber washers over the balls on each end:

Vise handle bumper

After which the handle gives off a pleasant thump and won’t nip a careless finger.

This is an old trick and certainly not original with me; the occasion being that I just replaced the old and much-abused washers which were letting the clank through again. IIRC, a retail package consisting of both red rubber garden hose washers and black rubber O-rings followed me home from a tag sale, so I used both.

2012-10-04