Homebrew PCBs

On Monday 30 August 2004 06:27 pm, Stefan Trethan wrote:
> > What are you switching?  How many positions do you really _need_?  Have
> > you noticed that rotary switches are in large part going away,  or at
> > least they have been since the fifties?  There's a reason for that.  Feel
> > free to take this over to Electronics101 if we get too far off the topic
> > for in here.

> I need 2*10 positions, and can only get 2*6 or 1*12.

Sounds about right.  The way they used to do that was to stack two switch 
wafers, not a big deal.  I'm sure that such a part is out there and available 
somewhere,  though whether it's available at a reasonable cost to you with 
where you're located is another issue that I can't really address.

> For selecting cell count on a battery charger (no current at all).
> Almost all handheld meters i've ever seen use rotary switches, and all i
> took apart had "custom" printed contacts. Oh, yes, there was one rotten
> piece of bad engineering that had four buttons instead. The damn thing had
> dozens of design flaws, like blowing up each time you pulled the current
> plug....
>
> I could try to pull some mechanical stunt and stack 2 1*12 switches.
> I don't know if that would be possibe with the switches i can get.
> But then, one switch for 2.50eur is not exactly cheap, not speaking of 2...

That *IS* cheap!  What does it look like?  The typical rotary switch I know of 
has a metal front with mounting bushing that the shaft comes through,  with 
two "legs" that are crimped beyond the point where they go through the wafer. 
The heavier-duty ones,  and the ones that are designed for more than one 
wafer,  are done with longish bolts that go through the metal part and 
through the wafers with spacers in between each wafer and between the last 
one and the front metal,  to space them out.

Wafers seem to be phenolic,  typically,  though I've also seen some that were 
done in ceramic as well.

Contacts can be shorting or non-shorting,  or all sorts of strange 
configurations in some applications.

Maybe if you can find an old tv set that's good for scrap you can do something 
with the tuner?  It'll require some mechanical work,  but it may give you a 
usable multi-level rotary switch with (perhaps) enough positoins.  Typical 
here is channels 2-13 and a "UHF" position that selects a different 
tuner,what's typical there?