The forecast of several pleasant days will have me in the garage wrenching on bikes, doing car maintenance, and finishing home chores.
Back next week …
Obligatory cat(erpillar) picture:
Category: Electronics Workbench
Electrical & Electronic gadgets
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Switchyard Hum
For reasons not relevant here, I walked along IBM Rd to the end of Sand Dock Rd and back, passing the switchyard serving the IBM Poughkeepsie site:
Street View – 1 Sand Dock Rd The overall capacity is surely in the tens of megawatts and there’s an overwhelming hum coming down that driveway:
Switchyard hum Those peaks and the corresponding lines in the waterfall show the equipment emits acoustic energy all the way up to about 480 Hz, call it the eighth harmonic of 60 Hz.
Transformer steel has low magnetostriction, which produces most of the noise at even harmonics of the 60 Hz power line (because each cycle has two current maxima). The spectrogram shows the switchyard handles enough current to emit plenty of odd harmonic energy, with a notable peak at 180 Hz.
For comparison, standing a few feet from the transformer behind a medical office building along IBM Rd:
Transformer hum No 180 Hz energy from that transformer!
Moving a few feet further away dropped those peaks into the background.
Even with my deflicted ears, I think can hear the switchyard hum from a considerable distance along the road, so maybe the background isn’t as quiet as I think.
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Solar Garden Light
I salvaged a solar garden light from the Vassar Community Gardens midden heap and stripped it down:
Solar garden light – internal The single IC is a YX805 “solar lawn light boost control chip” and the resistor-like thing is a 82 µH inductor setting a 13 mA input current.
Cleaning off some minor corrosion, charging the NiMH cell, and soldering an amber LED onto the pigtail wire brought it back to life.
It’s now perched on the porch railing where it catches some afternoon rays:
Solar garden light – deployed Maybe we can think of something better for it to do …
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Kenmore 158 Sewing Machine: COB LEDs Redux
Having harvested the COB LED lighting from the Kenmore 158 Mary gave to a friend, I took advantage of a sewing pause to install the hardware on the 158 she now uses:
Kenmore 158 – needle light detail That’s the sandblasted presser foot atop the original glare-y metal plates.
For the record, this is inside the machine’s power connector:
Kenmore 158 – power connector wiring Power for the original glowworm incandescent light comes from the two rightmost terminals: 120 VAC switched by the machine’s power button. Those terminals now go to a new, much more flexy, cable for the 12 VDC power supply, with a step-up supply for the needle LEDs.
An overview of the wire routing:
Kenmore 158 – COB LED wire routing There’s now a 9-pin JST SM connector between the repurposed serial cable and the LEDs, mostly so I can add another light bar to the front in the unlikely event it becomes necessary.
The rear light bar wire once again burrows into the machine above the presser foot lever:
Kenmore 158 – COB LED bar wire routing All the LED wiring fans out through the endcap:
Kenmore 158 – COB LED needle heatsink You can just barely see the edge of the strip of LEDs epoxied to the bottom of the machine nose, on the right of the needle.
If I were inclined to rebuild the needle LEDs, I’d use flexy silicone wiring instead of the Teflon insulated coax. The black insulation wouldn’t be nearly as pretty, but it’d be *way* easier to cut to length and solder.
The patient survived the operation and sewing should resume shortly …
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Newmowa NP-BX1: 2025 Batteries
A new sextet of NP-BX1 batteries for the Sony AS-30V helmet camera arrived:
Newmowa NP-BX1 – 2022 vs 2025 The traces:
- Blue = 2025 batteries
- Red = 2022 batteries when new
I don’t know what the bump in the middle of the new battery discharge curve means. Something weird in the chemistry, I suppose. Getting good batteries from Amazon surely remains a crapshoot and I now have four chargers.
Recharging all six batteries required 5488 mA·hr, just over 900 mA·hr apiece. Running the camera on a one-hour bike ride burns 600-ish mA·hr, so that’s comforting.
Comparing the new results with the 2022 batteries tested last month:
NP-BX1 – Newmowa 2022 in 2025-06 The upper traces appear in red in the first plot, the lower curves come from three years of use.
I’ll deploy the two best 2022 batteries (D and F) in the SJCAM M20 keeping watch from the Forester’s dashboard.
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Newmowa NP-BX1: Three Years Later
A pair of the 2022 batch of Newmowa NP-BX1 lithium batteries for the Sony AS-30V helmet camera no longer survive a typical hour-long bike ride:
NP-BX1 – Newmowa 2022 in 2025-06 The best four have a capacity down 14% from the good old days and the weakest pair are down 29%.
The camera uses 1.9 W, so a battery with 2.5 W·hr capacity should last 78 minutes, but about 400 mV of voltage depression causes the camera to give up before using its full capacity.
So they have a useful lifetime of maybe two years in our regular bike riding schedule and I should have bought replacements last year. I hope the next batch isn’t New Old Stock or recycled cells.
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HQ Sixteen: Under-arm Lights
With the nose ring lights in place, I soldered up eight more 24 V LED strips to light the quilt under the HQ Sixteen’s arm:
HQ Sixteen – under-arm lights – bottom view A simple fixture aligned the strips for soldering:
HQ Sixteen – under-arm lights – soldering fixture I intended to peel the masking tape off the glossy cardboard, then use it to keep the strips aligned while I pressed the PSA adhesive on the back of the strips to the machine. The silicone molded over the LEDS turned out to be supremely un-stick-able to the tape and the strips got far more handling than I planned, but I think the adhesive will work.
The cable from the power supply now has a pair of JST SM connectors on the end. Although crimping two conductors into the same pin is not good practice, all 14 of the LED strips draw an aggregate of maybe 130 mA, so I think it’ll suffice.
The JST connectors hide behind the ribbon cable going to the machine’s front panel, so there’s not a lot of basis for arguing they’re unsightly:
HQ Sixteen – under-arm lights – side view The finished part of the quilt passes under the bottom bar on the left (the rear of the machine table) and forms an ever-increasing roll around the top bar; the white fabric leader attaches to the edge of the quilt. The LED strips illuminate the in-progress part of the quilt under the arm and should be far enough forward to not snag on the rolled-up finished part.
I think there’s now enough light to work with:
HQ Sixteen – under-arm lights – top view We recently decided the motor stall Heisenbug has vanished, perhaps due to my re-soldering the motor power supply components on the PCB. It’s hard to tell with Heisenbugs, but sometimes they decohere into a desirable state.
After the better part of a year, Mary’s vintage HQ Sixteen runs better than new!
A blog search unearths an extensive project in reverse chronologic order.
The Smell of Molten Projects in the Morning 