27 Apr
2010
27 Apr
'10
11:52 a.m.
On 4/26/2010 12:25 PM, Tony Duell wrote
But it's certainly a lot hardwre to make an 'incremental design' on a
PCB. Which viertually all my projects are.
> I can think of one very good reason : If
you're the sort of mortal whose
> designed don't always work first time, or if you prefer to desgin a bit,
> get that working, add on the next bit, and so on, then it's a lot easier
> to do tha, make changes, modify things on prototyping board than on a PCB.
>
I'm not sure that's a valid reason. It's pretty easy to
make mods on a
PCB as well, unless the initial design is really FUBAR. > And I
wondeer... For a one-off project how does the time taken to lay out
> the PCB check it, etc compare to thr time taken to wire it up by hand on
> a prototyping board.
>
If (and a big IF) someone is very good at reading pin numbers backwards,
has good prototyping skills, and doesn;t get in a
hurry, I'd say the
prototype direction wins. But, I can see that swinging in favor of PCBs
very easily:
* It's easy to get messed up while looking at the back of a board as
to pin numbers. Sure, they make guides for that, but then that's
just another product you need to have in your kit.
As I said, this has never bothered me.
* You still have to design it in something
(napkin, graph paper,
Do you/ I jeust grab a suitable bit of prototpying board (cut to fit
whatever case it's going to end up in if it's going in a case), roughtly
position the IC sockets (leaving room for others if possible) and start
soldering. I design as I go, based o nthe results of testing the bits
I've buiit and got working.
etc.) For ultra simple (<10 major
components) designs, I can see
the napkin as OK, but beyond that, hand drawn schematics (that
don't take as much time as a PCB app) get hard to read and prone
to error.
Again this has never been a problem for me.
* Moving from idea to prototype can be addictive
to the point that
corners are cut, creation is done in haste, and then mistakes are made
Probably the most important reason
* wirewrapping and such don't work nearly as well with SMT. You
either need to buy SMT->through hole adapter boards (another item
to stock in the kit), or use kynar, glue, and a patient hand to
Oh come on. You hve to buy the ICs, the other cvmponets, sockets, etc no
matter what method you use. Buying the SMD adapters is not a problem. And
having all major devices socketed is very useful on a prototype (you can
easilty re-use the chips, you can remove them and force signals high or
low for testing and so on).
solder a "dead bug style" SMT IC to
your prototype
The last item is what drove me to PCB for all my projects. Many newer
parts only come in SMT variants.
-tony