Advice For Selecting Modern Equivalent IC's & T's

[orson198305]

I am not street wise with electronics yet, eg, codes prefixes and what they mean on ic's and transistors. But can build using a schematic without too many problems. Most of the circuits i want to build are pretty old and contain discontinued parts. Surely you don't have to go through spec sheet after spec sheet to find something similar? This might be a really stupid question but;

Is there any clues in the coding of components?

[Nigel Goodwin]

It all depends what you are looking for?, generally transistors aren't too hard, experience tells you what to use. With IC's they are often too specific, and there might be no possible replacement.

[cpemma]

Originally posted by orson198305
Is there any clues in the coding of components?

Only a very simple (and rarely useful) one AFAIK;

The first letter B is for silicon, A is for germanium (rarely used now). The second letter indicates the type; for example C means low power audio frequency; D means high power audio frequency; F means low power high frequency. The rest of the code identifies the particular transistor. There is no obvious logic to the numbering system. Sometimes a letter is added to the end (eg BC108C) to identify a special version of the main type, for example a higher current gain or a different case style. If a project specifies a higher gain version (BC108C) it must be used, but if the general code is given (BC108) any transistor with that code is suitable.

There are reference books giving transistor specs and equivalents; Newnes was once found in most public libraries, but seems to have vanished like the dodo.

[gmphadte]

In the japanese components
2SA and 2SB are PNPs
2SC and 2SD are NPNs

On americans the first number represents number of leads
1N has 2
2N has 3
3N has 4

Gajanan Phadte

[orson198305]

Ok guys starting to make me feel really stupid now lol, this will explain why rectifier diodes 1N4001 start 1N, cool, i totally didn't think in that direction.

[Nigel Goodwin]

Originally posted by orson198305
Ok guys starting to make me feel really stupid now lol, this will explain why rectifier diodes 1N4001 start 1N, cool, i totally didn't think in that direction.

Don't feel stupid! - why should you know? (I didn't either!), it's the wrong side of the Atlantic for us.

[poobah]

The codes won't do much for you in terms of substitutions.

First and foremost, get your hands on the original data sheet. That will define your replacement.

Most manufacturers are providing decent parametric search engines so you can that way (old datasheet in hand).

Many times the original manufacturer will have a substitution guide.

Many manufacturers have "competitor cross refererence" guides as well.

Never be afraid to type the part number right into Google... you'll be surprised.

TV and Stereo shops often work from a catalog that lists semi's and a re-labeled equivalent... I can't remember the names of the catalog providers ECG?... NTE? Their scam is to help you with part number by giving you THEIR part number instead in the hopes that you will buy their $3 version of a 5cent part. Ping "anatech".

There once was a group of books Called "IC Master" that were awesome. I think the web has all but killed the books but the service still exists:

www.icmaster.com

And as a last resort, you can post your part number here, and recieve recommendations for cryogenically treated, gold plated, silver conductored, imitation NOS, blessed by the Dal(a)i (Salvador or Lama) himself substitutes -