Re: gEDA-user: Re: Pointer to 3d CAD?

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Thu, Nov 02, 2006 at 12:53:13AM -0500, Dave McGuire wrote:
> On Nov 1, 2006, at 10:58 PM, DJ Delorie wrote:
> >>   It all depends on what you're into.  I've been discussing a
> >>project with a friend that would involve building what amounts to a
> >>copy of the PDP-8 ("Straight-8", no suffix) with individual
> >>transistors.  It's fun, cool, and highly educational in a number of
> >>areas.
> >
> >Are you going to be true to the time and use TO-92, or "cheat" and use
> >SOT-535's?
> 
>   Well my tentative plan is to duplicate the functionality of the  
> individual boards, but not to scale.  Many DEC machines of that era  
> were built with "Flip Chip" boards, 2.5"x5" PCBs with card-edge  
> connectors that typically implement relatively little logic...say, a  
> pair of flip-flops.  The PDP-8/S, for example (a model I've studied  
> much more closely than the Straight-8), uses maybe fifteen different  
> types of Flip Chips, but hundreds of them.  I'm thinking of cloning  
> the functionality of those Flip Chips board-for-board, but much  
> smaller, perhaps the size of a large postage stamp, using 0805  
> resistors & capacitors and SOT-23 transistors.
> 
>   Though I have no problem with TO-92 packages, I'm no longer a big  
> fan of through-hole components in general...too much of a pain to  
> work with when compared with surface-mount, and using smaller parts  
> makes for a much smaller...perhaps even desktop...finished unit.

I am prototyping my Ronja RX on TO-92 2N3904. But it's a bit pain in the ass
because I have to cut the base as short as possible and put possible capacitors
hooked to base as short as possible too. Very unhandy for unskilled user.

The final version will be SMD, MMBT3904 or how it is called, which is easier
for ordinary user because there is nothing to botch, and will be smaller.  The
electronics is now adding about 10 unnecessary centimeters to the
optical head, with increasing wind resistance and a need for a little
more robust construction.

CL<
> 
>   I'm very hot to do this, but I won't be able to devote much time  
> to it anytime soon, as my employment is going away in a few weeks and  
> I'm busy scrambling to find work in the middle of a technological  
> wasteland.
> 
> >The Museum of Science in Boston has a computer that plays tic tac toe.
> >It's made of wooden Tinker Toys.
> 
>   That is just too damn cool.
> 
>               -Dave
> 
> -- 
> Dave McGuire
> Cape Coral, FL
> 
> 
> 
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