What is vdb in electrical?
Each row is fed from a different phase (A, B, and C below), to allow 2- or 3-pole common-trip breakers to have one pole on each phase. Electrical Basic Abbreviations and Full Forms. Electronic Engineering VDB abbreviation meaning defined here. Looking for online definition of VDB or what VDB stands for?. Watch Photos, images and wallpapers of VDB ELECTRICALS PVT LTD.
Once the context is known it makes sense. This is a troubleshhoting example form a 'textbook'. The writer says:
The voltages shown are arrived at using a simulator - some are close to impossoble to calculate by normal means - including some in the example originally given, as they require iteration - which a simulator uses as of right, but which is not usually needed for 'hand calculation.
Here is how the results are caused in the fault situatuons described. He uses 'shorthand' terms to describe faults. eg
R1s = R1 short circuited - eg solder splash or bad PCB etching or just possibly a resistor failure (not usually).
Q1 = transistor used.
R2o = R2 open - R2 missing, dead, broken track, bad soldering.
...
Examples:
R1s - Original example. Base short to V+ so Vbase = V+. Transistor is haaaaard on. Ibe is limited only by Vbe drop and Re. Vbe is almost 1 volt due to higher than usual current - about 0.85 Volt. The spec sheet allows only an approximate estimate of this value. As Ib >> Ic (extremely unusual) Vce sat is very low - = 0.03V !!!. Ic = V/R = (V+ - Vc)/Rc = (10-9.2)/3k6 = .8V/3k6 = 0.222 mA. As Ie = Ve/Re = 9.17V/1k = 9.17 mA then Ib = Ie - Ic = 9.17-0.222 = 8.95 mA. SO Ic/Ib = 0.222/8.95 = 0.025 = forced beta of 1/40th. Small signal transistors typically have Betas (Ic/Ib ) in the 50-600 range. "Forced Betas where Ib is purposefully set highertahn needed to achieve nomonal saturation or a specified Vce may be set to 100 or 50 or laybe even as low as 10 if a really high level of overdrive is wanted. In this case the forced Beta of 0.025 (40 mA of base drive for every mA of collector current) is over 1000 times higher than you'd usually see in extreme cases. The transistor is ON.
Which explains the most unusual sotuation originlly described. Most of the others are much simpler.
R1o: R2 pulls base to ground. Q1 is hard off. Vc = V+ as no I_rc Ve = 0 as no I_Re
R2s: Same effect as R1o above - base is again at ground with same result.
R2o: Transistor is turned on by R1 and voltages staiblise at "expected" levels. Ib = (V+-Vb)/R1 = 0.662 mA. Ie = Ve/Re = 2/68/1k = 2.68 mA. Beta = Ie/Ib = 2.68/0.662 = 4 = very low. Vce = (2.73-2.68) = 0.050V = very hard on.
Res: Transistor hard on via R1/R2 divider drive.
Reo: Emitter is left "floating and emitter floats somewhat below Vb set by R1/R2 divider. e is high Z and meter measurement of voltage changes Ve.
Rcs: A1 is an emitter follower with c at V+. Vb set by divier and Re sets Ie.
RCO: Mainly be diode action as in 1st case above. Here Vb is set by divider so is < 10V so Ie is liower than in 1st example.
In the coin collecting hobby, one set of initials is far more familiar - and readily recognizable - than all others. The initials are "VDB" and they stand for the name of Victor David Brenner, the artist who designed the Lincoln cent.
What makes these initials famous is the fact that they appear on the rarest of all the Lincolns (excluding such mint errors as the 1922 "Plain" and the 1955 and 1972 doubled dies). Indeed, it was these initials that MADE the coin rare in the first place.
The coin, of course, is the 1909-S VDB Lincoln cent.
The very first Lincoln cents carried Brenner's initials in large, conspicuous letters at the base of the reverse. But outcry arose almost at once that this outsized "signature" was not only disproportionately large but also inappropriate simply as a matter of principle.
Under public pressure, the U.S. Mint removed the offending letters soon after the start of production - after a mere 484,000 pieces had been struck with the initials at the San Francisco Mint. The "S-VDB" has been a highly sought after rarity ever since.
In 1999, the hobby will observe the 90th anniversary of this venerable and perennially popular coin. And it's interesting to note that while the coin has given lasting fame to Victor D. Brenner, his name, in turn, has enhanced the appeal of other numismatic collectibles, as well.
This was dramatized a decade ago when a group of Brenner medals, plaquettes and related materials came up for sale at a New York City auction conducted by Bowers and Merena Galleries. They attracted strong interest and drew impressive prices.
"Items designed by Brenner are quite popular with collectors," said well-known numismatic cataloger and scholar Michael J. Hodder, then director of research for the Wolfeboro, N.H., company.
"A medal by Brenner," he said, "will bring perhaps 30 percent more than a medal by someone else without a coinage connection - just because Brenner designed the Lincoln cent. If the piece has a Lincoln motif, the price goes up another 40 percent. And if his name appears prominently on the medal or plaquette, then you have a REALLY salable piece."
The Brenner material in that auction came from the collection of the late Glenn S. Smedley, a prominent numismatist who served for many years on the board of governors of the American Numismatic Association. Smedley greatly admired Brenner's work, and over the years he not only formed an important collection of items designed by the artist, but also wrote extensively on the subject.
In a booklet entitled "The Works of Victor David Brenner," Smedley pointed out that the man who designed the all-American Lincoln cent was not an American by birth.
Brenner was born of Jewish parents on June 12, 1871, in Shavli, Lithuania, a small town near the Baltic Sea. His father, a metal worker, was skilled at carving and engraving - and young Victor demonstrated similar gifts at an early age.
While still in his teens, he left for America, arriving almost penniless in New York City in 1890. But he soon found a job as an engraver, and during the years that followed he sharpened his talent by attending evening classes at Cooper Union. In 1898, he went to Paris, where he spent three years studying under such leading French medalists as Alexandre Charpentier and Louis Oscar Roty.
Brenner produced a number of impressive medals during the first decade of the 1900s, and his reputation was growing as the end of the decade approached - and with it the observance, in 1909, of the 100th anniversary of Abraham Lincoln's birth.
In the year or two preceding the observance, Brenner prepared appealing portraits of Lincoln for special centennial medals and plaquettes. Then, in the summer of 1908, fate brought him in contact with President Theodore Roosevelt.
The president was posing for a Panama Canal service medal being designed by Brenner, and the artist suggested the notion of a coin honoring Lincoln. Roosevelt invited him to furnish proposed designs - and within a matter of months, the idea became a reality.
The Lincoln cent has long been regarded as the single most popular coin with basic collectors - the coin that most collectors cut their teeth on, so to speak. It's less well known, however, that a parallel market exists for other works of art by Victor Brenner.
"Obviously, the clientele is far smaller and far more select," Hodder said at the time of the Smedley sale in September 1988. "But the people who collect Brenner artworks are very enthusiastic.
"Brenner items are always very popular. There's no comparison with Norweb-quality coins, for example, in terms of prices realized. But the pieces are very colorful, they're very attractive, they have a good, strong following - and the prices seem to get better every year."
At the 1988 auction, prices were particularly strong for a group of large bronze pieces bearing Lincoln portraits - portraits strikingly similar to the one used by Brenner on the cent. A bidder paid $660, for example, for an uncirculated Lincoln medal 63 millimeters in diameter - more than twice the size of a U.S. half dollar. Two uniface rectangular plaquettes measuring 89 by 67 millimeters, sold as a single lot, brought $550.
Such prices, to be sure, are very small potatoes compared to the current cost of many coins. In the medal market, though, they were - and still are - worthy of note.
"So much of medallic Americana is really unexplored by the mainstream collector," Hodder observed. "And I think it's largely a matter of ignorance - including widespread ignorance of just how much these things are really worth."
In Hodder's view, anyone who collects Lincoln cents ought to have "medallic art by Brenner, as well, and it ought to be in large, module size."
While Brenner is best remembered for his works portraying Lincoln, he fashioned numerous medals and plaquettes on other subjects, too. Those in the 1988 sale, for example, included attractive pieces depicting such important historical figures as Amerigo Vespucci, the Italian explorer after whom America is named, and John Paul Jones, the American Revolution's foremost naval hero.
The sale also featured two offbeat - and intriguing - Brenner-related items that might come under the heading of "memorabilia."
One was described by the catalog as a "presentation cent." Brenner, it appears, acquired examples of the 1909 VDB cent made at the Philadelphia Mint (in much more plentiful numbers than the S-mint version) and placed them in cardboard holders - one to a holder - which he then signed and gave to friends and associates. The cardboard says simply: "Compliments of Victor D. Brenner." This brought $462 at the auction ($420 plus a 10-percent buyer's fee).
The second unusual item was a short but fascinating letter from Brenner to Farran Zerbe, one of the leading numismatists of the day. Evidently, Zerbe had written to inquire whether the motto "In God We Trust" would appear on the new coin - a query no doubt prompted by the absence of the motto on gold coins the previous year (and also on the Indian Head cent, the coin being replaced by the Lincoln cent).
Brenner's letter, written in a broad scrawl, was brief and to the point:
This changed hands for $275 - $250 plus the buyer's fee - at the 1988 sale.
