Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Some cyclists complain that motorists don’t give them enough room while passing. That’s less of a problem for recumbent bikes, but this gets me a lot more clearance:
Bike trailer with propane tank
There’s one section of very nice and totally gratuitous 6-lane highway (NY Route 55 near the NYS DOT Region 8 HQ; I think they’re just showing off) where drivers normally edge over to the left side of the right-hand lane where I’m riding. With a 20-lb propane tank lashed to my bike trailer, most folks have no trouble whatsoever with a double lane change into the far left lane…
I ran into an amusing situation on a recent family bike ride with our GPS-to-APRS trackers running: my ladies were transmitting a few seconds apart. As a result, I had to listen to a pair of very short data bursts in quick succession throughout the whole ride.
Under normal circumstances that doesn’t happen, because I set the TinyTrak3+ trackers to delay during and wait a second after a voice PTT that collides with an automatic beacon. Somehow they never managed to delay an APRS beacon to knock the synchronization off kilter.
So I tweaked the automatic transmission intervals to make us relatively prime: 179, 181, and 191 seconds. That’s close enough to the original 180 seconds as to make no difference, while now ensuring that we won’t collide with each other for very long even if we should get aligned.
An alternative is SmartBeaconing, which I’ll turn on in a while after I collect a bit more data.
If you have some spare CPU and power, you can join the Great Internet Mersenne Prime Search and help find new primes, albeit ones much larger than I need…
The rear wheel of my bike popped a spoke while I was riding along a section of unimproved trail trail. Actually, it’d be more accurate to say “as-abandoned” railway line; they ripped out the ties and graded the baby-head ballast more-or-less level. It wasn’t really suitable for a long-wheelbase recumbent bike, but I really hate white-water rafting, which was the other choice.
Anyhow.
Of course, the broken spoke was on the sprocket side of the rear wheel. I discovered this when we were out of the most rugged section, so I have no idea how long I’d actually been abusing the wheel.
I released the rear brake, gingerly rode to the campsite, then installed the FiberFix emergency spoke I’ve been carrying around for a few years. After snugging the cord and tightening the nipple, I added a turn to each of the two adjacent spokes, making the wheel true enough to continue the mission.
FiberFix spoke in action
The other end simply passes through the spoke hole in the hub. It doesn’t mind the deformation pressed into the hub.
Hub end of FIberFix spoke
Much easier than removing the sprocket cassette under field conditions, that’s for sure!
Back home in the shop, I installed a new spoke, tightened it up to match the others, backed out the extra turn in the adjacent spokes, and the wheel trued right up.
I originally built the wheel using a Park Spoke Tension Meter, which is a wonderful tool. If you build wheels, even occasionally, you really, really need one. Lace ’em up, tighten uniformly, then tweak just a little bit for a perfectly true wheel.
And, yeah, Phil hubs on all three bikes. I hate adjusting bearings. The man is gone; may his legacy live forever.
Mary’s feet are exquisitely sensitive to irregularities in the insoles of her shoes, which poses a real problem with her bike shoes: those SPD cleat recesses are no good at all.
This is a view down into one shoe, with the SPD cleats adjusted all the way to the rear. That leaves a large recess in the front, which was painfully obvious to her sole. The white shape is the gap filler…
I pressed a sheet of paper across the gap to get the general shape, traced it twice onto a slab of 0.060-inch aluminum with a nice pebbly paint job, and cut the two pieces out. A few conversations with Mr Belt Sander, a few licks with a rat-tail file, and they dropped right onto place. The recess is slightly curved, but I didn’t have to bend the pieces to fit.
I laid duct tape across the whole affair, put the insoles back in place, and it was all good.
The backing plate is 0.072 inch thick and she was content with the difference.
In previous shoes, with the cleat near the middle of the adjustment range, I’ve stuffed epoxy putty into the gaps. That works, but it doesn’t bond to the (miracle engineering plastic) soles and tends to crumble. This is Not A Good Thing…
We spent the night aboard BB62 in Camden NJ, with our bikes lashed to a post on the dock. Follow the light-color brick track from the upper-left GPS point across the dock to the black dot marking a memorial stone: we tied up just to the left of that spot.
Position Jitter – ZNU at NJ2BB-15
NJ2BB-15 is the APRS digipeater aboard BB62 with an antenna high in the superstructure. While I didn’t have any trouble with RF reception, packet collisions pose a problem in a dense urban environment. For what it’s worth, essentially everything in the superstructure is an antenna; the NJ2BB ham shack is a wonder to behold.
BB62 starboard side
The point-to-point jitter is about 20 meters (18.52, says the GPS info dump), so you’re looking at the un-augmented GPS accuracy of a long-term stationary object. I’m sure there’s a slight registration mismatch between the satellite imagery coordinates and the GPS coordinates, enough to put the upper-left point across the dock.
If you get the chance, take the tour. The guides are retired Navy, some served aboard BB62, and they take their storytelling duties very seriously. The bunk space, even with air conditioning, is claustrophobic at best; a tip of the bike helmet to you folks who live in these machines!
[Update: Our daughter discovered three itchy bites in a line across her tummy the morning after spending a night in the bunks. That means BB62 has bedbugs, which you do not want to bring home in your luggage. As a result, I cannot recommend an overnight on BB62, alas. We wish she’d mentioned that before we got home…]
[Further update: when I reported this to the folks at BB62, they had an exterminator check out the berthing spaces and conclude they have no bedbugs on board. That’s encouraging, but I still heartily recommend that you follow the same decontamination procedures that you should use after all trips.]
It turned out one rider in our group was an active-duty Rear Admiral who, evidently, could (or should) have supervised the signal gun firing after Colors and Taps. She was traveling incognito, though, and didn’t stand on ceremony.
I was running my GPS-to-APRStracker while on a bicycling vacation along rail-trail paths around southeast PA. I expected good coverage in urban areas and not much in the woods, which is pretty much how it worked out.
Here’s a plot of my track (from aprs.fi), with superimposed half-size PHG (Power-Height-Gain) “circles” for the digipeaters that caught my signal. Clicky for many more dots.
The first part of the ride, from BB62 in Camden NJ to Pottstown PA, had good coverage.
A bus jaunt from Pottstown to White Haven, just north of I80 along the Lehigh River gorge, accounts for the abrupt jump. I dropped off the face of the earth at White Haven, riding south along the Lehigh River to Jim Thorpe, then along some undeveloped trails to resurface just north of Allentown.
Strangely, there are no points east from Allentown to the Delaware, then south along the river & canal to Trenton. We stayed overnight on Bull’s Head Island where, as nearly as I could tell, there were no other APRS signals at all.
A plot of all the APRS activity (and, thus, all the active digis) for a different 24 hours shows the gaps in coverage match up fairly well with where I wasn’t heard. These are also half-size circles, but don’t take topography into account. Notice that the trails along the Delaware run right through the no-coverage zone!
PHG Allentown to Camden – 24 hours
I’m not sure why the digis caught me going into Allentown and not going out, but the vagaries of RF propagation remain inscrutable. Even if the digipeater could receive a clear signal, a collision between two transmitters can kill both packets stone cold dead. In addition, I’m using 100 Hz tone squelch and some receivers may not decode packets with tones.
Another possibility is a path (WIDE1-1, WIDE2-2) that allows only two hops to an Internet gateway. In those remote regions, it may well be that I should have had a path allowing three or four hops. However, I wasn’t hauling along all the programming gear to tweak the TinyTrak3+ on my bike. If I lived around there, I’d have a better appreciation of what’s needed to get out of the valleys.
This is a tweak to the previous design, based on some road testing.
An attenuator on the output of the MAX4467 voice amp allows gains below unity. Right now, the MAX4467 has Av=5 and the attenuator cuts it back by about 1/5, so the overall gain is about unity. I have a bunch of surplus electret mic capsules and some have come through really hot; this allows backing the gain way down with the mic amp set to Av=1.
That requires stiffening the Vcc/2 supply by swapping in a 33 µF cap for the original 1 µF unit. If you don’t do that, the amp turns into a oscillator: the attenuator jerks the Vcc/2 supply around, which feeds back to the non-inverting input of the MAX4467. In principle, the gain should be less than unity, but I wouldn’t bet on it.
The MOSFET relay sometimes didn’t quite turn on from the piddly 4 mA available through the ICOM IC-Z1A’s mic power supply; it was vaguely temperature dependent. I returned to an ordinary optocoupler with a CTR of about 100% driving a 2N2907 PNP transistor, as in the first-pass design that you never saw.
The two 2N2907 devices allow either a through-hole TO-92 or SMD SOT-3 package, depending on what you have and the power dissipation you need. In my situation, the SMD version suffices, with less than 100 mV of VCE saturation.
Let me know if you need the Eagle PCB files or PCB layouts.
[Update: I’m not convinced the Vcc/2 supply is stiff enough. I ripped out the attenuator and cut the amp gain to 1.0. If I get some really hot capsules, I’ll think it over a bit more.]
The Smell of Molten Projects in the Morning 