I left out one detail: the ring trip current threshold is usually around 10-15 maDC. Much lower, and it would be tripped by the normal ringing current peak value if multiple phones are on the same line.
Standard ring voltage is nominal 86VAC, 20 Hz, riding on a -48VDC battery feed. The "ring trip" is the threshold detector that signals when the ringing phone has been answered (it looks at the DC current and then disconnects the ringing voltage when te threshold is exceeded).
Re the other tale above: I have another "shocking" story, 100% true (and I really do remember every detail). As a baby, I somehow woke up from a nap, and climbed out of my crib (which my parents were unaware that I could do). I was crawling around on the floor of our apartment, and found this shiny thing that I picked up and carried around in my explorations. It was a brass house key. As I roamed, I came to a wall and spotted something on the wall that turned out to possess slots in it (an AC outlet, long before U-grounds were invented). For some reason, it seemed the shiny thing would be perfect for exploring the slots. I pushed it into one slot. The next thing I knew, I was on the far side of the room, and the slotted thing was all black! Thus, I have ever since claimed I was destined from that point to become an EE, as I literally had electricity flowing through my veins!
mhrackin: GREAT story! I live in a house where all the AC outlets have those infernal slide covers. I doubt they saved many toddlers, but they sure make me look for my reading glasses before I plug anything in. And they manage to complete confuse my guests who've never seen the contraptions before.
How much ring voltage is there, anyway? Enough to zap a well-grounded tyke?
Mhracken: I heard what you're saying, but I'm not sure we're at "opposite" views. After all, what is an oligopoly with only one participant? I absolutely agree with your view on standards that facilitate or hinder innovation.
Unfortunately, many standards include construction requirements. Look at almost any electrical safety standard (UL, CSA, CEE, etc. ) and you'll see lots of specifications like creepage distance. Once, I made an off-hand comment (intended as a joke) to the responsible engineer from UL for the old UL-1959 standard (for customer-premise telephone gear) that the requirements for the original modular wall jacks hadn't considered the case of a baby in a wet diaper crawling on a concrete floor (thus being grounded) sticking a finger into the jack opening at the exact moment ringing voltage was applied. Sure enough, the next revision included a new "ring trip" requirement, including a sketch of the baby in a wet diaper sticking a finger into the jack! That later became the requirement for the "trap door" in the jack that would cover the opening, along with a difficult-to-open spring latch that made it nearly impossible to insert a plug into the jack in a semi-blind location. I have no idea how many babies were saved by the resulting mandated redesigns, but I suspect it was pretty close to zero!
I suspect it's just the opposite. If you look at what has driven many standardization attempts in the past, the unspoken agenda is to commoditize the products, to make them as cheap as possible. Of course, many times this has failed because (especially in electronics) it doesn't stop innovation (thankfully!). Where it has worked, it has achieved the goal: passive surface-mount components have become so cheap (at the piece level) that the cost to place them dwarfs the component cost! It also leads to oligopolies, as a very few suppliers eventually emerge as the result of M&A and driving the less efficient out of business. There are also other pitfalls; my favorite is the tendency of the European-driven standards groups to issue sham "standards" that essentially combine every local/national standard into one monstrous document that continues the intent of most of these "contributions," which is protection of the "home market."
I do favor standards that preserve the ability to innovate. Ones based on performance do; ones that dictate implementation do not. Another pitfall I have seen often is to perpetuate bad practices like setting tolerances, etc. to what is possible, not what is needed! The major offenders in that category include Germany and Japan; the latter is the epicenter of this latest attempt.
First, this story WAS already reported in the Japanese press. The information is in the public domain.
If you find the media's instinct to dig further objectionable, well, that's a whole different discussion.
But here's the thing. I read the Japanese story, and found it not so clear -- in terms of what the companies' goals are.
I kept thinking if the auto industry is finding some need for "standardization" in power semiconductors, what would that be. If you are in the power semiconductor business, wouldn't you like to know more?
I find the presumption of this report to be wholly inappropriate why are these companies obliged to explain themselves to the press? I believe it is appropriate and reasonable practice for business organisations to decide what should be disclosed and when, whatever the reasons commercial senstivity or otherwise the presumption that the press need to know all about this is over stated.
A Book For All Reasons Bernard Cole1 Comment Robert Oshana's recent book "Software Engineering for Embedded Systems (Newnes/Elsevier)," written and edited with Mark Kraeling, is a 'book for all reasons.' At almost 1,200 pages, it ...