Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
After five years and one cleaning, the PTT button on Mary’s Tour Easy became increasingly intermittent, both failing to activate solidly and sticking closed (there being nothing quite like a hot mic during a good hill climb), so it’s time for an autopsy:
Failed PTT Switch – as extracted
The snap dome is much more scarred at the central contact:
Failed PTT Switch – snap plate
That might be a gold flash coating, but it’s pretty well worn away where it hits the central contact:
Failed PTT Switch – center contact
Those scratches surely happened during the previous cleaning pass, as I don’t see any way for the dome to create them.
The corner contact also shows some scuffs, along with a scar where the dome corner pivots:
Failed PTT Switch – edge contact
All in all, though, it worked quite well.
The replacement switch, also intended for indoor use on a keypad or some such device, pivots around the front edge and may be easier for her fingertip to activate:
New PTT Switch – installed
Hot melt glue seems vastly underrated for how wonderful a structural material it is.
If this one lasts five years, I’ll be perfectly happy.
Having recently promoted a pair of Radford Tri-Star 90 speakers to the Sewing Room, it was time to make them presentable:
Radford Tri-Star 90 speakers – taped grill
The original foam grill covering had disintegrated and left fossilized adhesive over the metal gridwork. Being not much for historic accuracy, I used double-sided duct tape (the blue barrier film peels off) and stuck some allegedly acoustic foam in place:
Radford Tri-Star 90 speakers – re-covered
The foam is a single sheet wrapped around three sides and, after some whittling, measured 19.5 inches tall and 19.25 inches wide. The width surely depends on how snugly it’s stretched, so allow a bit more and trim to fit.
Duct tape probably isn’t the right adhesive for the job, but we’ll see how long it lasts. I really did not want to use spray glue and doubted my ability to slobber liquid stickum without oopsing the cones.
The speakers sounded great back in the day and they definitely sound much better than my deflicted ears can hear now. Mary thinks they’re OK and that’s all that matters.
Those are not the best bulbs for the application, as they’re allegedly equivalent to 20-25 W halogens, but I had some on hand from a previous relamping project and they seemed promising.
G8 halogens have a flattened section just above the pins that these G8 LED bulbs lack:
G8 halogen vs LED bulb – front view
It’s more obvious from the side:
G8 halogen vs LED bulb – side view
The curvature of the soft silicone LED body magnifies the components to look like they fill all the available space, but a little deft X-acto knife work flensed the body down to fit the microwave’s ceramic socket without exposing any of the electrical innards.
Because the LEDs dissipate only 3 W and barely get warm, I replaced the original translucent glass diffuser panels with (yes, laser-cut) clear 3 mm acrylic, then tucked a strip of aluminized mylar above the bulb to bounce some of the light from the upper chips down where it would do more good. I think it’s possible to melt the acrylic with a stovetop mishap, but we don’t make those kinds of recipes.
They’re not daylight shining on the stove, but they’re much brighter than the halogens at maybe 10% of the power.
With the new battery mount & buck converter box installed on Mary’s bike, I updated the running light circuitry to match the ones on my bike. The original wiring just supplied 6.3 V from the headlight circuit, but now the four wire ribbon cable from the electronics box carries 6.3 VDC from the buck converter and a 6 VDC signal going high when the DPC-18 display’s “headlight” output goes active. The latter goes into an optoisolator pulling down Pin 2, telling the running light to stay on continuously.
The optoisolator sits next to the Arduino Nano’s Reset button:
Tour Easy Running Light – unified light top
The black wire barely visible below the optoisolator jumpers Pin 3 to ground, telling the firmware that this is the front running light.
The black & white wires from the top of the optoisolator connect directly to the ribbon cable entering on the other side:
Tour Easy Running Light – unified light bottom
The gray wrap of clear silicone tape mummifies the wire-to-wire soldered connectors.
The firmware now pays attention to the jumper input, so I need only one source file for both front and rear lights:
if (digitalRead(PIN_POSITION) == HIGH) {
Blinks = String("i e "); // rear = occulting
Polarity = true;
}
else {
Blinks = String("n e "); // front = blinking
Polarity = false;
}
Tour Easy Running Light – electronics box interior
The baseplate is aluminum for (probably unnecessary) heatsinking under the buck converter, which sits atop an aluminum snippet isolated by heatsink tape, with a pair of nylon M3 screws holding everything together.
The solid model looks about like you’d expect:
Running Light – power box – Show view
I planned to run the mounting screw through the lid with the nut on top, so the central pillar would prevent crushing the lid. As it turned out, it was easier to put the nut inside the box on the aluminum plate and be done with it:
Tour Easy Running Light – electronics box nut
The frame tube was too close to get a socket wrench in there, so I deployed a 1/4 inch square drive to 7/16 inch hex adapter and cranked the nyloc nut down with an open end wrench.
As before, all the connectors are non-waterproof JST-SM, but at least they’re jammed tucked inside the box under its acrylic lid:
Tour Easy Running Light – electronics box installed
Which has a square of electrical tape over its unused central hole. Le sigh.
The mounting plate cable had an XT60 bullet connector pigtail that I chopped off and replaced with 45 amp Powerpoles to match the Bafang motor:
UPP Battery Mount – Powerpoles
Mostly because I have a box of Powerpoles and their crimper.
Now Mary’s bike has the freshest battery and I get to run the three older ones in sequence on my bike. Yes, we now have fourcolor-coded battery keys.
These switches carry absolutely no regulatory approval markings, although they do claim to carry 10 A at 250 V, which I take with another load of salt.
At least here in the US-of-A, a 240 VAC outlet has two “hot” wires carrying 120 VAC 180° out of phase, which means both conductors must be switched. Despite the voltage rating, only the L path goes through the clicky switch, with the N path along a strap just below the switch toggle. Using it on a 240 VAC circuit will kill you stone cold dead should you assume whatever it controls is turned off.
I secured the Line and Neutral conductors with crimp connectors, rather than just wrapping the 20 AWG wires around the screw terminals, because the case halves join without perimeter nesting: a bare millimeter of air in the gap between the halves separates the terminals from my fingers. A layer of good electrical tape on each side improved that situation, but not by much.
The complete lack of strain relief clamping on the cords prompted me to route the wires around the screw bosses. After a function check, squirts of hot melt glue anchored the two cords somewhat better.
Aaaaand I secured that loose strap on the right with an (identical to the others!) screw from the Tray o’ Random Screws. The other switches had both screws installed, so this one must have been a QC escape.
They suffice for the purpose, but … caveat emptor!
It turns out either of the two middle slots should work, but the crimps look better in the smaller one.
Admittedly, the instructions are thin on technique, but I only wrecked four pins while retraining my crimping hand. The key trick is indexing the insulation fingers on the step inside the jaw, thus putting the socket box or the male pin outside where it won’t get smashed flat. Squishing those fingers from their normal splayed condition into a rectangular shape helps fit them into the jaw against the step.
Living in the future where the right crimping tool doesn’t cost five Benjamins is great …
The Smell of Molten Projects in the Morning 