FT82-43 Slit Toroid: Construction

The FT82-43 toroid slit easily enough, using the same diamond-wheel Sherline setup as for the smaller toroids:

FT82-43 toroid - slit

FT82-43 toroid – slit

I’m pretty sure that chip at 1 o’clock happened while it was clamped in the vise between two cardboard sheets, but I haven’t a clue as how it got that much force. In any event, that shouldn’t affect the results very much, right up until it snaps in two.

Although the current will come from a (rectified) 120 VAC source, the winding will support only as much voltage as comes from the IR drop and inductive reactance, which shouldn’t be more than a fraction of a volt. Nevertheless, I wound the core with transformer tape:

FT82-43 toroid - wrapped

FT82-43 toroid – wrapped

That’s 3M 4161-11 electrical tape (apparently out of production, but perhaps equivalent to 3M’s Super 10 tape) cut into half-foot lengths, slit to 100 mils, and wrapped ever so gently.

The biggest offering from Big Box o’ Specialty Wire was 24 AWG, so that’s what I wound on it:

FT82-43 toroid - wound

FT82-43 toroid – wound

That’s 56 turns, which should convert 2.2 A into 1000 G (enough to max out the Hall effect sensor) and is more in keeping with 24 AWG wire’s 3.5 A current rating.

The insulated core requires just under 1 inch/turn, so figure the length at 56 inch. The wire tables show 26.2 Ω/1000 ft, so the DC winding resistance should be 120 mΩ. My desk meter has 0.1 Ω resolution, which is exactly the difference between shorted probes and probes across the coil: close enough.

The inductance is 170 µH, so the inductive reactance at 120 Hz  = 128 mΩ.

Now, for a bit of armor…


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Another Bike Ride, With Gratuitous Smog

Large Pickup - Small Brain

Large Pickup – Small Brain

He could claim to be accelerating after a stop signal and that’s just how those big Chevy “clean diesel” engines work, even with DEF and DPF in full effect.

In point of fact, this was deliberate:

Large Pickup - Small Brain - Penumbra

Large Pickup – Small Brain – Penumbra

I wish no ill on any man, but, should the Fates decree that a big pickup must be found wrapped around a tree, I have a recommendation.

We were northbound on 9W, returning home after an end-of-summer party.


Cycling the Hudson Valley: 2014

Seven days and 300 miles of pedal pushing:

KE4ZNU route - 2014-07-28 through 2014-08-04

KE4ZNU route – 2014-07-28 through 2014-08-04

We rode north to the start of the Cycling the Hudson Valley ride in (wait for it) Hudson, rode south while crossing the Hudson six times, then I rode north from Da Bronx while the other 100 riders proceeded south to the tip of Manhattan and the finish line in Brooklyn. Mary, alas, drove the last few days to avoid aggravating a tender tendon.

While everybody else had a touristing day in Hyde Park, we slept in our own beds for two nights.

Everything you need to know about modern bicycle touring:

Cycling the Hudson Valley - Charging Station

Cycling the Hudson Valley – Charging Station

The straight line along the right side of the map, from just below the New Croton Reservoir to Hopewell Junction, represents data loss from riding in a valley, plus knocking the coaxial power plug out of the battery pack where the South County Trail becomes one with Rt 100 / Saw Mill River Road for a few miles.

That last day had plenty of hillclimbing, even on the rail trail, but with a rewarding section of Rt 52 that drops 500 feet in a mile; I hit 41 mph while passing under I-84.

A good time was had by all!


Bike Helmet Earbud Iteration

Based on having to seal the rear vent hole of the previous earbud, I did the same for the new one:

Earbud - blocked vent

Earbud – blocked vent

The audio quality was terrible, so I tried another bud with a foam windscreen over the hole and a hole punched in the middle of the double-sided white foam tape:

Earbud - foam over vent

Earbud – foam over vent

The audio remained unintelligible, so I tried an upscale (but still cheap, because surplus) Koss earbud, first without blocking the vents and then with snippets of Kapton tape:

Koss earbud - tape over vent

Koss earbud – tape over vent

The earphone has three slits on each side, but only the middle slit has a hole penetrating the case; it must be a stylin’ thing.

That sounded better, so I’ll roll with it. There’s supposed to be a foam cover over the housing, but those things always get grody and fall off; there’s not much point.

As nearly as I can tell, contemporary earbud designs optimize for volume (dBm/mV) and thumpin’ bass, all to the detriment of actual audio quality. Based on numerous samples over the years, there is zero correlation between price (admittedly, on the low end) and audio quality (admittedly, with my crappy hearing).

I own a pair of very nice (and thoroughly obsolete) Shure E2c sound-isolating ear beetles that sound great (even with my crappy hearing), but I’m unwilling to chop them up for the bike headset …

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Clymene Moth

The first Clymene Moth we ever saw:

Clymene Moth

Clymene Moth

It’s a poor picture, but the moth was up and away after that; as always, the poor picture you get is better than the great picture you might have gotten.

A few days later, we spotted two of them on a brick wall, so there must be a bunch more out there.


Uphill Rain Leader

You can’t make this stuff up:

Expecting water to run uphill

Expecting water to run uphill

As nearly as I could tell, the vertical downspout along the edge of the building ends level with the top of the drain grate. If that convenient rock were high enough to level the last length of pipe, the elbow would be above the end of the downspout.

The architectural drawings for the apartment complex surely didn’t look like that.

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Monthly Image: Overblown Vette

I should do something like this to the Forester:

Seriously Blown Vette

Seriously Blown Vette

We were volunteering at the annual Locust Grove Classic Car Show, which also included a monster 1913 FIAT made in Poughkeepise.