[sdiy] Expo question and unrelated dumb matrix idea

[Harry Bissell Jr]

I'll take the DUMB MATRIX IDEA for $1000

AMP makes some socket pins that solder into
a PCB and have a HOLE in the bottom that allows
a pin to protrude.

And they have closed-bottom sockets.

Two parallel PCBs (could be indetical in design and
rotated 90 degrees) with these sockets installed ???

Watch out. they have some with limited contact
insertions, and some that are better. The better ones
are called 'component test' sockets iirc.

We used these for OPTO-22 module mother boards at one
time. They come in a wide range of sizes.

The open bottom ones have to be hand soldered (so they
don't fill up. Should be no problem for you...

H^) harry

--- Tom Arnold <xyzzy at sysabend.org> wrote:
> First, the expo question.
> 
> Is there such a beast as an inverse expo converter,
> or is there a different
> name for this that I'm not thinking of at 2:30am? 
> I'm doing a pot to
> current->voltage converter and the responce I'm
> getting acts very Expo (
> lots of movement for not much voltage change and
> them whammo ).  The pot
> *is* linear.
> Unfortunatly I'm trying not to modify the control
> the pot is in, so
> connecting it across the supply rails and taking a
> voltage from the wiper
> isnt an option.  I dont need to be exact, just need
> to compensate in a rough
> way for the crappy curve I'm seeing.
> 
> Next, the dumb matrix idea.
> 
> Since I obviously have too much spare time and too
> few projects, I played
> with something else tonight too.  I want to build a
> small pin matrix with
> small being the operative word ( I'd like 15x15 in
> about 2" square ).  The
> idea I tried that actually seems to work is taking
> strips of machinepin
> sockets for SIP IC's, trimming the pins off then
> grinding the bottom lightly
> with a dremel until I hit the cavity.  I was afraid
> the contacts might pop
> out the bottom once it was open but in this case (
> Augat sockets ) they did
> not.  Now an actual sewing pin goes right through
> the top socket and can be
> lined up on a second set of SIP sockets which are
> unmodifed to provide the
> second contact.  Its less work then it sounds
> although I only made a 5x5 as
> my test matrix.  May be cool for matrix patching a
> noise box or something.
> 
> Next run to the surplus places I'm going to try and
> find some older
> microprocessor sockets that are solid pins across
> the bottom unstead of
> having an empty area around the die as this would
> give me a solid top and
> bottom structure to play with.
> 
> I did mention it was a dumb matrix idea... but it
> may be a fun toy for
> someone.
> 
> -- 
> 
>
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>  - Tom Arnold       -  Free Synth DIY webspace
> http://www.sdiy.org 
>  - SynthGeek        -
>  - BBD Fanatic      -  "...is it a virus, a drug, or
> a religion?" 
>  - echo evho wjxo   -    Juanita Shrugs. "What's the
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