partial P112 kits

Tony Duell ard at p850ug1.demon.co.uk
Wed Jun 23 12:35:59 CDT 2010


> > [1] Heathkit prodcued an education kit to teach SMD soldering. You ended
> > up making a flashing light or something uisng SMD components. Needless to
> > say that one did come with an unpolulated PCB
> 
> I built that kit, c. 1990.  There were two PCBs - the one I remember
> had a line of SOT-23 LEDs and an LM339 in an SO package.  There were a

Right. I must admit I built very few Heathkits. They were expensive 
(compared to other kits) in the UK, and while theire manuals were 
excellent, I didn't need that level of hand-holding. Cheaper kits tended 
to come with a PCB layout diagram and a parts list and you were told to 
populate the board, and that level of detail was enough for me. So I 
mis-remembered (if I ever knew) what that Heathkit SMD kit consisted of.

> couple of machined pin socket pins for inputs - you could insert an
> electret microphone to turn the board into an audio level display, or
> replace the microphone with an LDR to display light levels.  The
> louder or brighter the room, the taller the line of lit LEDs.  The
> only through-hole parts were the input pins and the CR2032 holder.
> Everything was SO and SOT-23 and 1206 sized.
> 
> At the time I did it, it was challenging to me, but at least it worked
> the first time.  Since then, with practice, 1206 and SO stuff is old
> hat, and I work down to 0.5mm QFPs and 805s with no difficulty
> (IOB6120, Makerbot Sanguino and Arduino boards, Makerbot wristwatch,
> stepper controllers, etc).

A lot of it comes down to practice (as with most things :-)). 

> 
> Even though I'm over 40, I still have steady hands and good close-in
> vision.  I wouldn't hesitate to do most SMT short of BGAs.  I'm

Yes, I don't hacve the tools to do BGAs (yet!). 

I think it would be reasoanble for the advert/webpage for a kit to say 
what was involved -- if there was any SMD work (if so, what sort of 
components were invovlved), if there were BGAs, etc. And possibly to 
prvided several 'levels' of kit -- some of the manufactuerers of model 
steam enginers over here supply their porducts in 3 grades -- assembled 
and ready to run; fully machined -- you have to clean up parts with hand 
tools (files, etc) and put it all toguether ; or castings and metal stock 
where you have to use a lathe, etc to make parts. 

> keeping my eyes out for a 20X-25X binocular dissection microscope for

Now that would be fun. I found a nice little stereoscopic magnifier (*15 I 
think) for \pounds 5.00 in a charity shop a year ago -- yes I did buy it. 
And I was given a good binocualr eyepice but one objective (so not 
stereo) microscope some years ago. I didn't need either, but I like nice 
toys :-)

> the day when I can't see so well.  Until then, I'll just keep at it
> like I have been.  It may be inexpensive to get "kits" pre-soldered
> overseas, but I don't mind the work, and I've seen more than a few
> hobby-level products with low yields due to poor construction.  If I
> build it myself, I know it's good.

Even if I say so myself, I agree with you. If I've soldered a connection, 
I know it's done properly. And the number of bad conenctions I've seen in 
new stuff recently is amazing.

-tony



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