On Sat, 06 Dec 2008 04:19:03 -0500, "Michael A. Terrell"
wrote:


Eeyore wrote:

John Larkin wrote:

On Fri, 5 Dec 2008 19:33:40 -0500, "gore"
wrote:

I work at an electronics contract manufacturimg facility. We do work for
several companies and I wonder why they use different labels on the
schematics and pcb's to refer to IC's. Some of them have a U1, an A1, and
X1, or an IC1. Why do they do this? Is there a standard used to label IC's
in a schematic? Just curious why this is.

Thanks


U (IC) = IC

Q (TR) = transistor

D = diode (CR is archaic) (well at least we can agree on that. Why not U and
Q too whilst at it ?)

T (or TR or TX ) = transformer

L = inductor

A = assembly

R = resistor (all kinds)

RN = resistor network.

C = capacitor (ditto)

P, J (CN, CON, CONN, sometime J) are connectors

I prefer J for user selectable 'jumpers/headers' that take shorting links.

B = battery

F = fuse

K (RL, RLY) = relay

S (SW) = switch

V (V for valve) = tube

IC, CON, HDR, TR, VR, CHO, RN, RV, RLY, SW, LED and such are all
amateur inventions.

No they make vastly more sense. How can you justify the use of Q for a
transistor for example ? A quansistor ?

It was justified by the fact that it was available. It doesn't need
any more justification for people who know what they are doing.



I also use CD = decoupling capacitor to distinguish from a capacitor 'in
circuit'.

Also RT = thermistor.

Graham

I justify my use of mil-std reference designators by the fact that
using arbitrary junk would convince my scientific and aerospace
customers that I'm an amateur who is ignorant of industry standards. I
really wouldn't want that to happen.

You may as well scatter parts around on a layout at odd arbitrary
angles, or use florid gothic script on orange front panels. Or invent
your own revision and ECO standards. Mount heatsinks with duct tape.
Send any messages you like.

John