On Saturday, September 26, 2015 at 8:02:45 PM UTC-7, John Larkin wrote:
> They give you a zillion choices. Like if you want a mosfet from 20 to
> 50 amps, there are 30 or more, in tiny increments as low as 0.1 amps.
Yeah, the database was cobbled together from different datasheet formats,
by folk who hadn't any way to redesign the engine.
I've seen it done better, in pre-computer days. You get a bunch of cards, with
perforations around the edges, and a notcher tool. Notching from the card edge
to the perforation sets a bit, which can represent transistor type (notch #1: Ge;
notch #2: SI) or maximum voltage (0-20 notch #21; 20.1-80 notch #22; 80.1-120,
notch #23 and so on).
Set the cards in a holder tray and slide a wire probe into the "Si"" notch, then lift.
All the cards that come up on the wire, are NOT the transistors you want,
because Si transistors had that notch cut (and their cards stayed in the tray);
set the unsuitables aside. Then on to the next requirement; any combination of
include-this or exclude-this on any of the bits, was achievable with a modicum
of thought.
But, someone had to really THINK about the criteria; a 470 uF capacitor and 500 uF
capacitor aren't really different (20% tolerance, you know) but if the manufacturer
data is to be presented in the catalog, it'll LOOK different when the database is
built. Loose ranges work better than numeric entry.
And 2048 kHz quartz crystals are entered into the database distinct from 2.048 MHz,
and distinct too from 2.0480 MHz... unless someone really thinks.
Type-of-gizmo labels are always an issue; why does DigiKey insist
that you only search after you determine that you want an aluminum
electrolytic capacitor? Aluminum polymer or tantalum require separate searches.
The card-based thing suffers, too; my lonely old stack (kept for nostalgia, not use)
hasn't been updated with new cards since 2N1702 was a common part. Mouser's
search engine is better.