Spare Discrete Components?

From: William Donzelli <william_at_ans.net>
Date: Thu Sep 25 14:42:08 1997

> Many collectors have multiple systems and peripherals that can be
> cannibalized for parts if anything in their primary machine fails,
> but what about maintaining an inventory of discrete components such
> as ICs or those 150,000 Mfd filter capacitors?

It really depends on you. Many of us are packrats that keep just about
anything more useful than a burnt out light bulb. Others do not want to
keep anything other than common spares. Your space has much to do with
this.

By all means, use this list for parts requests! Unless what you need is
truely exotic, I think (hope) most of us would sell the spare for the
price of postage (at least that is how much of the old ham radio community
works).
 
> I reviewed the availability of parts for many of my systems and found
> that most components are readily available. Others were more difficult
> to locate or were listed under another industry part number (e.g., a
> "25LS2521" is actually a "74LS688").

Yes, just about any (non-custom) chip can be found if you look. Even many
of the extremely obsolete numbers (700 series RTL, 300 series ECL,
etc.) are not impossible (hard, yes) to find.
  
> Do you think it's worth the effort to purchase spare discrete components?

I keep quite a stock of chips and discrete components around, probably
more than most people. I also keep old boards so I can pluck out chips as
needed (I just found some early seventies boards loaded with 900 series
DTL and 9N00 series TTL, all in cerdips. Will I start removing the chips?
No, not now - the boards they are in make handy carriers.). Of course,
keeping an inventory is for the well discplined - something I need to work
at.

> Are there any specific categories of devices or parts that are prone to
> damage, failure, or extinction?
                      ^^^^^^^^^^^
There was a small thread about this when the list was very young. It is
probably worth starting again. Any takers?

I will start with a few:

Early or weird EPROMS: 1702s, 2704s, 2708s, 2516s, 2532s.
Early glue: 300 series ECL, 400 and 4000 series TTL, 700 series RTL, 1000
    series ECL, 800 and 900 series DTL.
Glue made by unusual companies: Philco and Sylvania.
Early microprocessors: 8080 (they are drying up!), 6800 series support
    chips (6810, 6830, 6859, etc.). Also, early (licensed) clones, like
    the 9080, and the Intersil 6100.
Early memory: 4K DRAMs (I forgot the numbers).
Analogs: 1402A (I think) core sense amplifier, in cans.
Transistors: 2N404, just about any pre 2N1000 parts.
Passives: Not many, most are still available.

Additions welcome!

William Donzelli
william_at_ans.net
Received on Thu Sep 25 1997 - 14:42:08 BST