Invisible wrote:
> ...  although I also found ... a small bottle of white powder marked
> "KNO3"...

A little charcoal and sulfur and *you* *are* *in* *business* *!*

> Some capacitors are small brown things like little chocolate buttons. 
> (But significantly less tasty.) Then there's the "electrolytic" ones, 
> which are small blue things that look like they belong in a licorish 
> all-sorts bag. Some a really small (about 5mm diammeter). Some are a bit 
> bigger (15 mm diammeter).
> 
> When I was in my dad's loft, I found capacitors the size of friggin' 
> soda cans! o_O WTF are *those* for??
> 
> (I mean, are they that size because they have a higher capacitance or 
> something? I gather a capacitor is one of the few components where the 
> physical size of the device determines its electronic characteristics...)

A capacitor consists of a piece of electrolytic material sandwiched 
between two conducting plates.  The capacitance is proportional to the 
area of the plates, is inversely proportional to the distance between 
the plates, and is factored by the capacitance of the electrolytic 
material between the plates.  To get up to where capacitance is measures 
in farads (instead of microfarads), you need large plates, the thinnest 
possible spacing between them, and the best material to go between (as 
to which material is the best, I am not in the know).  The most reliable 
manufacturing technique is to take a thin layer of flexible electrolyte, 
  plate it with metal on both sides, insulate one of the two sides, and 
roll the plates up so that they take less room.

If they're old components, it may be that manufacturing techniques 
didn't allow the two plates of the cap to be closer together.  To make 
up for a lack of precision, you have to increase the area of the plates. 
  It all comes down to how thin the electrolyte can be and still 
physically separate the two plates (because if the plates make 
electrical contact, the cap becomes a wire).

> We also found a box containing more 14-pin DIL sockets then it is 
> humanly normal to have. And a bunch of 7400-series chips. In particular, 
> these are the original, obsolete, 7400 chips. 7400, 7408, 7402, etc. Not 
> 74LS00 or even 74S00, but vanilla 7400 TTL. They're that old.
> 
> We also found a stack of unopened boxes containing LEDs. Now when I was 
> at Maplin I bought a bag of mixed LEDs - which is great, because you get 
> a lot of LEDs for not much money, but OTOH they're all different. Now I 
> have a matching set!

Good.  Now you should be able to build a small, functioning processor. 
With pretty lights to show the data states.

Regards,
John

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