By turns: tinker, engineer, husband, author, amateur raconteur, recumbent cyclist, father, ham radio geek. So many projects, so little time!
Adapting the NP-BX1 battery holder to use SMT pogo pins worked well:
The next step is to add sockets for those 14 AWG wires:
Start by reaming / hand-drilling all the holes to their nominal size and cleaning out the pogo pin pocket.
Solder wires to the pogo pins and thread them through the holder and lid:
That’s nice, floppy silicone-insulated 24 AWG wire, which may be a bit too thick for this purpose.
The pogo pins will, ideally, seat with the end of the body flush at the holder wall. Make it so:
Dress the wires neatly into their pocket:
Butter the bottom of the lid with epoxy, clamp in place, set it up for curing, then fill the recess:
While it’s curing, make a soldering fixture for the 14 AWG wires:
The holes are on 5 mm centers, in the expectation other battery holders will need different spacing.
Solder it up and stick the wires into the base:
Jam a battery in and It Just Works™:
- Green = supply current at 20 mA/div
- Yellow = LED driver transistor base voltage
- Purple = other transistor collector voltage
- White = base – collector voltage = capacitor voltage
The measurement setup was a bit of a hairball:
For completeness, here’s the schematic-and-layout diagram behind the circuitry:
I love it when a plan comes together!
The OpenSCAD source code as a GitHub Gist:
A House Finch suffering from Finch Eye Disease prompted me to sterilize our feeder, which meant providing a temporary feeder to keep the birds flying. Having an abundance of lids from six gallon plastic cans / buckets, this made sense:
Which required an adapter betwixt pole and lid:
Which requires a bit of solid modeling:
The lids have a central boss, presumably for stiffening, so the model includes a suitable recess:
As usual, automatically generated support fills the entire recess, so I designed a minimal support structure into the model and cracked it out with very little effort:
The tangle off to the right comes from a bridge layer with a hole in the middle, which never works well even with support:
Didn’t bother the birds in the least, though, so it’s all good.
I loves me my 3D printer …
The OpenSCAD source code as a GitHub Gist:
It seems the DCW&WA SUV makes regular trips through the “No Motor Vehicles” bike access:
If it’s not them, then it’s somebody following their example.
Just because you can do something, doesn’t mean you should … but, of course, the ordinary rules apply only to little people, not public servants.
Someone in the bike advocacy apparat once told me I’m the most cynical, bitter person they’d ever met, at least on the subject of getting along with public servants. As I see it, I came by my attitude honestly.
A sterling knife followed me home after a Thanksgiving gathering:
The original cement, dating back to the middle of the last century, turned into friable dust around the blade tang:
I cleaned it out as best I could, buttered JB Quik epoxy around the tang and into the socket, joined the two, and let it cure in the natural position:
The rest of the knives in the set may need similar attention, but I’m not looking for trouble.
Posted in Oddities on 2018-12-08
Even though mice don’t seem like cuddly creatures, they ended their days snuggled together; we’ll just ignore the cannibalism thing.
Heck of a way to go, even for rodents. I renewed the steel wool blocking a gap in the garage door.
As part of converting the halogen desk lamp to LEDs, I replaced the hulking iron transformer with a flatter counterweight:
Under normal circumstances, you’d use something like steel or lead sheets, but Tiny Bandsaw™ can’t cut any appreciable thickness of steel and I gave away my entire lead stockpile, so I sawed disks from a pile of non-stick pancake griddles and drilled suitable mounting holes:
Another disk (from a formal aluminum sheet!) goes into the lamp head, with a trio of 3W COB LEDs epoxied in place:
The other side of the disk sports a heatsink harvested from a PC, also epoxied in place:
Realizing the head required only a little filing to accommodate the heatsink sealed both their fates.
A test firing showed the heatsink needed more airflow, which didn’t come as much of a surprise, so I milled slots in the lamp head:
Deburring the holes, blackening the sides with a Sharpie, and tucking a bit of black window screen behind the opening made the vents look entirely professional.
The small dome in the base originally cleared the transformer and now holds the entire 10 W LED driver, along with all the wiring, atop the counterweight sheets:
A cork pad covers the base for a bit of non-skid action:
I couldn’t convince myself filling in those sectors would improve anything, so I didn’t.
And then It Just Worked:
All without a trace of solid modeling or G-Code …
The DSO150 oscilloscope’s specs give a 200 kHz bandwidth, so a 50 kHz sine wave looks pretty good:
A 100 kHz sine wave looks chunky, with maybe 25 samples per cycle:
The DSO150 tops out at 10 µs/div, so you can’t expand the waveform more than you see; 25 samples in 10 µs seems to be 2.5 Msample/s, exceeding the nominal 1 Msample/s spec. I have no explanation.
A 10 kHz square wave shows a blip just before each transition that isn’t on the actual signal:
At 50 kHz, there’s not much square left in the wave:
And, just for completeness, a 200 kHz square wave completely loses its starch:
A 10% (-ish) duty cycle pulse at 25 kHz has frequency components well beyond the scope’s limits, so it’s more of a blip than a pulse:
The pulse repetition frequency beats with the scope sampling and sweep speeds to produce weird effects:
Tuning the pulse frequency for maximum weirdness:
None of this is unique to the DSO150, of course, as all digital scopes (heck, all sampled-data systems) have the same issues. The DSO150’s slow sampling rate just makes them more obvious at lower frequencies.
Key takeaway: use the DSO150 for analog signals in the audio range, up through maybe 50 kHz, and it’ll produce reasonable results.
Using it for digital signals, even at audio frequencies, isn’t appropriate, because the DSO150’s low bandwidth will produce baffling displays.