Dave,

> Dave Smith wrote:
>something I've being meaning to ask, just a general opinion. when I go to an electronic shop to purchase some
components they invariably do not have all the things on the list. this means a trip to another shop in the
hope of getting the component.
>
>is this the general way of operating?

I've always thought that most hobbies have an initial hump over which you have to get, including ours: a lot
of magazine articles say things like "start by soldering the links, using off-cuts from components".  If this
is your first project, you haven't got any off-cuts yet!  :-)

It's the same with parts - if you buy just the components you need for a project, you've got nothing to mess
about with, or for replacing parts that got fried, or that need experimenting with.  You need to build up a
bit of stock, or you'll spend much more time obtaining parts than actually working on projects.

I don't know if there's an equivalent chain of shops there, but Maplin here in the UK have "beginners sets" of
components.  It's a good place to start, at least for passives.  Have a look at their "GCSE Component Pack",
ref: GT66W at http://www.maplin.co.uk.  The list of what it contains is a good indication of useful stuff,
although it's a bit lacking in digital-specific parts.

For semiconductors there are a some that are worth having a few of:  you'll need a 7805 (5V regulator) for
pretty much any project.  1N4001 (or better: 4002, 3, 4...) and 1N4148 diodes are worth buying at least the
1st price-break-quantity (usually 10) because they turn up a lot.  For transistors people will have their own
favourites but I tend to have lots of 2N3904 and 3906 around.

Rather than crystals I like the 3-pin ceramic resonators that have their capacitors built-in, so you just
connect one across the PIC's two oscillator pins, connect the centre pin to 0V and that's it.  Cheap, easy to
use, reliable, and reasonbly accurate, and Glitchbuster has useful speeds (4, 10, 20MHz).

As far as PICs, I have to admit I've gone a bit mad ans bought all sorts of them over the years, to the point
where I've set up a spreadsheet for stock control... but choose what sort of things you think you'll be doing
and go for the PIC range that is best suited - and if you can't choose go for the 16F248 as a good
representative of the 18-pin 14-bit family.  (I feel a heated discussion brewing about that! :-)

This is just my ideas, and they are probably wrong, but you have to start somewhere, and any major howlers of
mine will be pounced on by the others here...

So plan to build up a bit of a range of parts, and you'll be well on the way with a lot of projects.  Of
course, whatever you buy, there will always be *something* that you haven't got, but that's life!  :-)

Cheers,




Howard Winter
St.Albans, England

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