When I rewired the guts of the digital tattoo power supply to eliminate the series foot switch, I kept the original wiring polarity, with the black wire to the sleeve and the red wire to the tip:
It’s the same color code I (strongly) recommend in the Squidwrench Electronics Workshops: use any color for the ground / common wire as long as it’s black, then, if you have a red wire, use it for the positive supply. You can use yellow for the higher supply voltage, but stop being clever.
I put suitably colored Powerpoles on the far end of the cable to replace the standard tattoo machine spring clip connector, so I can attach clip leads, battery test fixtures, and so forth and so on.
We wired the supply into a clip-leaded diode measurement setup with a current limiting resistor and a pair of multimeters to measure the diode current and forward voltage, whereupon we noticed all the meters displayed negative voltages and currents.
After a frenzy of wire-checking verified their setup was all good, I forced the simplest possible test, herein recreated on my bench:
Which produced this display:
After a brief exploration of “Trust, but verify” territory, we swapped the clip leads from the power supply and continued the mission.
Back on my bench, I pulled the supply apart and measured the voltage at the jack terminals:
Still negative. Huh.
The bottom of the power supply PCB shows exactly what you should expect by now:
The red wire near the top of the board is, indeed, soldered to the trace labeled GND and goes to the jack’s tip terminal; the adjacent black wire goes to the front-panel LED. Similarly, the black wire just below it, soldered to the same trace as the yellow wire, goes to the jack’s sleeve terminal; that trace also connects to a resistor leading to the trace labeled LED+ and the LED’s red wire.
Although tattoo machines run from DC supplies, their motors or vibrators don’t depend on any particular polarity and will run fine with a backwards supply.
Resoldering the red and black wires where they should go produces the expected sign at the jack:
Although measuring and plotting diode voltages and currents may seem tedious, actually wiring stuff together and taking data reveals how difficult the real world can be.
I trusted the supply’s internal color code and, although I’m certain I tested the Powerpoles, I obviously didn’t notice the meter’s sign.
Memo to self: Sheesh.
A useful CallerID name that’s not actually spoofed:
I get the distinct impression there’s a disgruntled employee somewhere in their IT department and, apparently, there are more than you’d think.
Ya can’t make this stuff up …
A pair of Barred Owls set up housekeeping nearby and we’ve watched them swoop down on rodents in the yard. We hope they succeed in raising their owlets!
This one kept watch on us as we cleared out a dead holly bush near the garden:
I took another picture at +1 EV to show more of the owl’s face; while blowing out the highlights:
Go, owls, go!
Taken with the Sony DSC-H5 and 1.7× teleadapter, because the Pixel phone’s camera just doesn’t have enough moxie at full zoom.
We have several high-intensity / long-attention-span home projects scheduled this summer, all of which will keep me away from the Basement Laboratory.
We’re OK, all is right with our world, but painting rooms and yard maintenance always take way more time than they should, while having close to zero intellectual content.
Like, for example, the result of a strenuous morning devoted to removing a severely overgrown holly bush:
I’ll post odd & ends a few times a week until maybe mid-August, whereupon I should get back to more usual pursuits.
Enjoy your downtime …
Prompted by RCP’s battery misadventure, I replaced a handful of the Forester’s incandescent bulbs:
Despite what look like “squeeze here” markings, you must push the license plate bulb holders toward the center of the car:
They were both stuck firmly to the trim plate, so I braced a screwdriver against the outboard edge of the trim panel, after which it becomes obvious how pressing inward compresses the (plastic) spring clip so you can pull the outward side of the holder away from the hatch.
Casual searching turned up a bunch of exceedingly helpful advice for anyone DIY-ing through a Forester.
The bulbs with conical ends, known as “festoon” lamps, (unsurprisingly) come in several lengths. The Forester bulbs are about 25 mm long, (unsurprisingly) much shorter than the 31 mm LEDs that seem to be the smallest available replacements, but (surprisingly) the socket tabs have barely enough compliance for the extra half dozen millimeters:
The LEDs are much much much brighter than the incandescents, although I’d prefer warm white to cool white. The cargo compartment lamp in the back is still way too dim; I don’t understand how Subaru decided on a plastic cover tinted tinted dark smoke gray.
All in all, a worthwhile upgrade!
I wonder how long they’ll last? I have one spare of each type …
Spotted another big turtle ready to cross the Dutchess Rail Trail along Daley Rd:
This must be the best season ever for turtles crossing vast expanses of asphalt, because I don’t recall seeing this many turtles during any previous spring. Confirmation bias in full effect, to be sure.
The picture is a dot-for-dot crop from the Sony HDR-AS30V helmet camera, demonstrating why image compression has more to do with resolution than the number of dots.
The dark spot in the grass, barely visible over on the left, is a dinner-plate-size snapping turtle recently teleported from the middle of Rt 376 just north of Robinson Lane:
The driver of the white van managed to stop both lanes during the rescue and, judging from the lack of gore, handled the snapper without incurring organic damage.
Color me impressed!