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.

Category: Home Ec

Things around the home & hearth

RCA Alarm Clock Dimming

Mary prefers dim digits on the bedroom alarm clock, far below what the usual DIM switch setting provides. I’d slipped a two-stop neutral density filter in front of our old clock’s VFD tube, but the new one has nice green LED digits that ought to have a tweakable current-setting resistor behind the switch. Indeed, a bit of surgery revealed the switch & resistors:

RCA clock – DIM switch and resistors

It turns out that the 220 Ω resistors set the DIM current, with the 100 Ω resistors in parallel to set the BRIGHT current. Weirdly, the display operates in two halves: one resistor for the lower and middle segments, the other for the top segments. The resistor numbers give a hint of what the schematic might look like:

RCA clock – LED current-set resistors

The current control isn’t all that good, because the brightness varies with the number of active segments. With 470 Ω resistors (yes, from that assortment) in place, the variation became much more obvious; the LEDs are operating far down on their exponential I-vs-V curve. We defined the result to be Good Enough for the purpose.

Four short screws hold the circuit board in place, but one of them arrived loosely held in a pre-stripped hole. I cut eight lengths of black Skirt filament, anointed them with solvent adhesive, dropped two apiece into each screw hole, and ran the screws back in place. I likely won’t be back in there, so it should be a lifetime fix:

RCA clock – ABS filament in screw hole

Done!

As with all the trade names you remember from back in the Old Days, the present incarnation of “RCA” has nothing whatosever to do with the original Radio Corporation of America:

RCA clock – data plate

2011-12-13
Christmas Cactus Time Lapse: Drat!

With macro lens adapter in hand, I started taking a picture a day with the intent of making a time-lapse movie:

Christmas Cactus flower bud

Of course, that particular flower bud fell off after three days.

We returned the plant to a cool location for the Christmas season. Evidently the kitchen was far too warm for best performance…

2011-12-12
Brita Pitcher Lid Hinge

This pitiful excuse for a hinge actually lasted far longer than I expected:

Brita pitcher lid hinge pins

Also much to my surprise, the plastic solvent-bonded to itself, although I doubt either of those pins will survive another four years.

The yellow discoloration seems to be most prominent on the inside of the lid, which suggests the water is nastier than they’d have you believe. The disinfection additive has switched from chlorine to chloramine and back to chlorine over the last few years, which may have something to do with it.

2011-12-11
Tux Cookie Cutter: It Works!

Sean reports that the first field test of the Tux Cookie Cutter went well:

Tux Cookies

I obviously need a few samples for QC purposes…

2011-12-07
Fruit Fly Traps

At some point we brought home a fruit fly starter kit that produced a zillion fruit flies in the worm compost bin; every time we opened the cover, half a zillion flies would emerge. After a bit of fiddling with the usual Internet recipes, I managed to produce something useful:

Fruit fly trap – overview

The trick involves making the liquid enticing enough to get the flies through the hole in the coffee filter top:

Frut fly trap – filter paper

I used about a cup of water, an ice cube of apple juice for sweetness (they are, after all, fruit flies), a tablespoon of vinegar for that delicious rotten aroma (they prefer damaged, easy to eat fruit), and a few drops of dishwashing detergent so when they hit the liquid they’re sunk.

The container must be tall enough to let them rise past the entrance opening on their way toward the light; I settled on the 2 pound ricotta cheese containers we have in abundance:

Fruit fly trap – results

That’s the catch after maybe a month at the end of the season, but it represents a week of activity back when we were breaking the infestation. I deployed four of those traps atop the compost bin to catch the half-zillion escaped flies and fired up the vacuum cleaner to extract the half-zillion remaining inside every time we opened the lid. After a few weeks of that, we’d managed to get ahead of their breeding cycle and the problem pretty much Went Away.

2011-12-05
Garden Sprayer Valve Spring Replacement

A garden sprayer awaiting repair emerged from the benchtop clutter. It’s an old one, with a metal shell and actual screws, so I could dismantle it to reveal the problem:

Garden sprayer valve – rusted spring

It’s evidently impossible to make a good, cheap, corrosion-resistant spring (pick any two, I suppose):

Garden sprayer valve – wreckage

Some rummaging in the Big Box o’ Medium Springs produced a slightly smaller spring that should last for a while; it’s good, free, and rust-able, if a bit too short.

Much to my astonishment, I found a length of 3/8 inch Marine Bronze rod in the stockpile and made a bushing to take up the remainder of the space:

Garden sprayer valve – new spring and bushing

It won’t get a good test until gardening season opens next year, but it seems to seal well enough.

2011-12-01
Dragonfly Garden Ornament – Eyeball Repair

This brass dragonfly has graced our garden for some years, but what seemed like a gentle tap during fall cleanup knocked both eyeballs out. The original adhesive looked like urethane, so I cleaned the sockets, applied a layer around the rim, and popped the marbles back in place.

The clamping looks painful…

Dragonfly Ornament – eyeball repair

Of course, that’s an unbroken Harbor Freight clamp…

2011-11-29