Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
it’s about that time of the year again: get ready to stock up on Kosher Coke!
Turns out that Coca Cola produces sugar-based Coke shortly before Passover each year; their usual high fructose corn syrup, while Kosher, falls into the Chametz category of grains that cannot be eaten during Passover.
Kosher-for-Passover Coca Cola bottle cap
Bottles containing the special sugar-based formula wear a distinctive yellow cap, so they’re easy to spot against the usual all-red array. To cross-check: the ingredients list runs: Carbonated Water, Sucrose …
A friend brought me a few two-liter bottles from a Jewish grocery store in the metro NYC/NJ area last year, shortly before I discovered that the local Target had a generous stockpile on the top shelf of their soda section. It’s allegedly available in cans, but I’ve never seen any.
NB: Pepsi uses yellow caps around this time of year to mark their bottles for some dimbulb contest. At least they did that last year and I’m sure it’s no coincidence. If the cap doesn’t have distinctive Hebrew symbology and the ingredients still include HFCS, it ain’t been cleared for Passover consumption.
While sugar-based Passover Coke is not the same as the old-school Coke you remember from long ago if you’re enough of an Olde Farte to do so, it’s as close as you’re going to get in these degenerate times.
In actual point of fact, sugar Coke tastes pretty much like HFCS Coke. That should not be entirely surprising, given the bazillion dollars they spend on development. Run your own side-by-side comparison, blind if you can, and report back.
If you plan to stock up on the stuff anyway, give the caps an extra twist to ensure they’re on tight before you put ’em on the shelf. I just cracked the final bottle from last year and it’s still plenty fizzy enough for me.
The phosphoric acid in either formulation is really hard on your teeth & gut, so don’t overdo it.
Update: As of 22 April, the local Target had a shelf full of yellow-cap Coke; they had none the week before Passover. Perhaps they got the last pallet a day too late? In any event, I stocked up my year’s supply in one shot. Admittedly, it’s $1.89 / 2 liter bottle, but it’s just for special occasions… and half a dozen bottles is a year’s supply for me.
The little red Battery Sentinel LED on our old Realistic (a.k.a. Tandy a.k.a. Radio Shack) clock radio was on this morning, which means that, once again, the backup battery needs attention.
It’s supposed to use an ordinary 9V battery, but it ate two or three of those a year. Given the absurd cost of 9V batteries relative to AA cells, that stopped making sense pretty quickly.
Most devices with backup batteries draw essentially zero power from them during normal operation. This gadget draws 6 µA.
An alkaline 9V battery has a capacity of about 500 mAh, maybe more with a low-drain load like this. That should last for a few years:
500e-3 / 6e-6 = 83k hours = 500 weeks = 10 years
Alas, the clock battery monitor is really fussy and triggers the LED when the voltage drops under about 8.5 V.
[Update: the clock does a “battery test” every day, which probably accounts for the short battery life. I haven’t measured that current… or the duration of the test.]
Fortunately, the clock case has a recessed bottom that fits a standard AA cell holder like a glove. I wired up 1-1/2 4-cell holders (yes, I should have used 7 cells, but I wasn’t sure what the upper voltage limit might be) to a standard 9V battery snap connector and screwed the assembly to the case.
Now all I must put up with are the weak AA cells I got from batteries.com; the most recent order was a disappointment.
Memo to Self: That snap connector has red = negative / black = positive!
One of Mary’s first investments when she got out of college was a sewing machine and she’s been using it ever since. Of late, it’s gotten a bit sporadic and the foot control seemed to be at fault.
The symptoms were that the foot control required too much travel (equivalently: foot pressure) to get up to speed, it started abruptly (poor speed regulation), and sometimes cut out without warning.
So I took it apart to see what I could do.
Two pins in the side hold the top cover in place and serve as pivots. Loosen the two visible screws in the center of two of the bottom feet, hold the top half of the case down, and slide the pins out.
A wedge on the top half presses down on the middle of the steel bar, pressing it into the rheostat. A dab of silicone lube on the wedge greatly improved that action.
Rheostat graphite wafers and contacts
The speed control itself is brutally simple: a carbon-pile rheostat in series with the 120 VAC 1 A sewing machine motor. The ceramic case and heatsink tab tell you that things get pretty toasty inside that Bakelite case.
Disassembly is obvious, which is one of the nice things about old electrical gadgets: you can puzzle out how they work and how the parts fit together just by looking. A slew of graphite disks slides out from two cylindrical tunnels in the ceramic case, followed by two graphite contact buttons. The brass fittings on the front have carbon dust on their raised surfaces, but are basically just stamped & machined metal parts.
No fancy electronics, no firmware, just a high-power (and utterly non-inductive!) carbon variable resistor.
The rheostat has three modes, in increasing order of pressure:
Off — no pressure on the foot control
Resistive speed control — resistance varies with foot pressure
Full throttle — rheostat resistance shorted by front switch
Rheostat speed control contacts
With no pressure on the foot control, there’s a generous gap between the contact bar on the back surface and the two graphite buttons sticking out of the ceramic case. There’s no way for the contacts to close by shaking or accident.
A bit more foot pressure connects those two buttons through the shorting bar across the back. Light pressure on the graphite disks means a relatively high resistance, on the order of several hundred ohms, and relatively low current to the motor. Of course, that also means the motor has poor starting torque, but … a sewing machine doesn’t need a lot of torque.
Increasing foot pressure squeezes the disks together and decreases the resistance. It drops to a few tens of ohms, perhaps lower, but it’s hard to get a stable measurement. The motor averages all that out and trundles along at a reasonably steady pace.
Rheostat full-speed contacts
Finally, the brass disk in the central case tunnel shorts the tabs on the two brass end contacts and lets the motor run at full speed. Increasing the foot pressure beyond that point doesn’t change anything; the spring-loaded shaft can’t deform the tabs.
The steel shaft and contact disk can short one or the other of the two piles, but that just decreases the already small resistance by about half. That might give the motor a speed boost instantly before jumping to full speed.
As nearly as I can tell, the carbon disks evaporated over the decades, as the piles seems quite loose and required a lot of foot motion to reach the first contact point. I lathe-turned a pair of brass disks about three wafers thick, so that they’d take up the empty space in the piles.
I also filed the brass end fittings flat so that they contact the disks over more of their surface. The first two disks looked like they had hot spots: loose carbon collected in the areas where the contacts didn’t quite touch them. I doubt that actually improved anything, but it’s the thought that counts.
The spacers worked reasonably well, although I wound up removing one graphite disk from each pile to ensure the full-speed contacts would close properly. They’re in a small plastic bag tucked under the aluminum heatsink tab, where they can’t get lost. With any luck, the bag won’t melt around them.
Rheostat with brass spacer button
A few days later, the sewing machine stopped working entirely. The foot control itself seemed to be working correctly, but a bit of poking around showed that the cord had a broken conductor just outside the strain relief. I cut the cord off at the strain relief, hacksawed the strain relief apart, then rewired it. The cord is now four inches shorter and everything works fine again.
I think this would be a nice candidate for a PWM controller, but then I’d have to shoehorn all that circuitry into the base of the sewing machine or add another cord to the foot control. Ptui, this works well enough.
Our old house has storm doors with brass latch bolts and brass strike plates. Brass-on-brass is nicely self-lubricating, unlike the steel-on-steel contraptions available these days, but of late our back door hasn’t been closing smoothly.
I fiddled with the door closer’s tension and release point to no avail, then (re)discovered that a dab of PTFE lubricant on the latch and strike plate makes the storm door close exceedingly smoothly. The base grease is clear and doesn’t make a black mess of things.
Duh.
Maybe everybody knows that and perhaps I knew it at one time.
I wrote about rebuilding the strike pull and shaft cam of these latches as CNC projects in my Digital Machinist column. Naturally, the replacement latches available in the local hardware stores didn’t fit the door, so the simplest course of action was some quality shop time.
Whenever I do anything even slightly out of the ordinary with magnetics, I must drag out my trusty Analon slipstick to make sure I haven’t lost a dimension.
Analon slide rule – front
Go ahead, you verify that the area inside a BH hysteresis curve is proportional to power loss in a given transformer core. I’ll wait…
Analon slide rule – back
My recollection is that I bought it in the Lehigh University Bookstore in the early 70s, but that doesn’t square up with the Analon’s history: they should have been out of circulation by then. I’m pretty sure I didn’t get it in high school, extreme geek though I was, and it’s for damn sure I wouldn’t have bought one after graduation. Come to think of it, if the LU Bookstore wasn’t among the last bastion of Analon holdouts, where would you look?
Over the decades I’ve penciled in a few handy dimensions they didn’t think of. Unlike most of the 600 597 (plus one in the Smithsonian) Analons in the wild, this one actually gets used, so it’s not New-In-Box (which means you collectors need not suffer from involuntary hip motions). It’s also not as grubby as it looks: I didn’t spend a lot of time futzing with the scans.
Anyway, that’s called beausage and it enhances the value.
Ordinary AC power outlets have fairly robust contacts, designed to last basically forever. I have no idea what the actual design life might be, but it’s rare to have an AC outlet fail.
This one did…
It’s an outlet expander at the end of an extension cord that provides six outlets. I’d installed it at my parent’s house (I was their go-to guy for electrical things, of course) and everything was fine. One visit involved rearranging some appliances and the adapter went nova when I plugged something into it.
Me being their go-to electrical guy, I’m pretty sure this gizmo didn’t experience a whole bunch of mate-unmate cycles in my absence. Most likely it was defective from the factory, so sticking a plug in once or twice was enough to break the contact finger.
Detail of burnt socket
Here’s a contrast-enhanced detail of the outlet in the lower-right of the top picture. The broken finger bridged the brass strips carrying the two sides of the AC line in the left side of the compartment.
Blam: brass smoke!
Oddly, the fuse didn’t blow. It was pretty exciting to have a small sun in the palm of my hand until the contact finger fell to the bottom of the compartment.
The bottom picture shows the offending finger. It’s pretty obvious what happened.
Errant contact finger
I’ve read of folks applying silicone lubricant (spray, perhaps) to their AC line plugs to reduce the mating friction in the outlet. While that sounds like a good idea, I think it’s misguided: you don’t want to reduce the metal-to-metal contact area by lubing it up with an insulator. In any event, that sliding friction ensures the contacts have a clean mating surface with low resistance.
Maybe use some Caig DeoxIT, but not an insulating spray!
For what it’s worth, do you know that the durability of an ordinary USB connector is 1500 cycles? That’s far more than PCI backplane connectors at 100 cycles. Some exotic high-GHz RF connectors can survive only a few dozen cycles.
Moral of the story: don’t unplug your stuff all the time. Use switches and stay healthy.
This took place many years ago, so the picture quality isn’t up to contemporary standards.
So FiOS has finally arrived here in the hinterlands and the latest teaser deal is $70/month for 10/2 Internet and anywhere-in-the-US VOIP. The ad mailers always tout the blazing speed (although that’s not what they offer in the teaser) and voice clarity.
But there’s an asterisk: the prices are always “plus taxes and fees”.
So I called the FiOS order line (877-896-2263) with two simple questions:
What, exactly, are those taxes and fees?
What, exactly, will they add up to each month?
After five minutes of telling the nice man everything they already know about me and giving him permission to read their own records of our account, I managed to push him off his script long enough to get a word in edgewise.
He tells me that the taxes and fees depend on my exact location and the services I sign up for. I point out that we’ve just established my address and he should know what services he’s offering, soooo what’s the price?
We go around and around:
He says the only way to find out is to sign up and get my first bill
I refuse to buy something without knowing the price
Eventually he offers to transfer me to billing, where he says (and I have no reason to doubt) that they’ll certainly tell me the same thing. Sounds like a good idea to me, if only to get to the next screen. He’s obviously miffed that I’m not following my lines in his script and just buying FiOS like a good sheeple.
I hear the usual beeps & boops, a snippet of their on-hold blather, and dead silence. Ten seconds later, the call disconnects and I get the usual “If you’d like to make a call, please hang up and dial again” message.
Right now we’re getting 13/2 Internet from Cablevision (aka Optimum Online) for $50 and a Verizon landline for $25.
Let’s see: slower Internet and marginally cheaper phone service, plus the asterisk. Not a compelling value proposition in our situation. But, then, we’re cheapskates.
Incidentally, the “taxes and fees” make up $10.61 of this month’s $25.09 phone bill. I have good reason to believe that if we buy two services from Verizon, the fees will add up to $20 or so. But there’s no way to find out without buying them first, of course.
I’m seriously thinking of killing the damn landline and struggling along with VOIP and our $5/month cellphone.
Update: Today’s mail brings an even better teaser with a different phone number: 877-896-5322. It’s still $70/month for a one-year “agreement”, but now with free activation and a $100 cash card and they guarantee the rate for two years. The kickbacks push it just under $60/month for the first year. Still has that asterisk, though. Not to mention that the offers just keep getting better and better … I’m sure the early adopters are astonished at Verizon’s sliding incentive scale.
Update 2: If you ignore the flyer and sign up for FiOS via the Verizon website, you get an additional $5/month off and you don’t have to deal with Verizon customer service. That brings it down to $55 plus the dreaded asterisk… I wonder what next month’s mail will bring?
Update 3: Another flyer and the offer is still $70/month, free activation, and $100 cash back. Somehow I think FiOS uptake around here isn’t living up to their expectations.
The Smell of Molten Projects in the Morning 