[sdiy] Four bit to serial translator

[Peter Grenader]

Guys and gal,

I'm in a bit of a pickle and it's getting sour here - thought you cold throw
me a life raft. 

I've added an asynchronous VC to Milton.  Quite the bomb.  It doesn't give
two sheets what the incoming pulse is doing, or even if there IS an incoming
pulse for that matter - when the VC input's A to D changes state, the
counter immediately reacts.  With this you can now set the start and end
step to wherever you want, plus achieve some amazing non-linear
progressions. Driving it with a sine wave being particularly interesting as
the sequence accelerates at both ends.

Problem is, as the name implies -  it's asynchronous. It functionally
remains a bit of a lame duck as there no way of syncing anything to it.  So,
unless you're planning on a legato glissandi, you're screwed.

I've worked out a way to extract a timing pulse, but its involving more
parts than I like, and I'm certain there's an easier way.

What I need is a short pulse each time the 4 bit word changes.  I tried just
monitoring the LSB, that works until it jumps to another of the same parity
and then it's lost.  I tired doubling the speed of the LSB to synthesize it
and that was totally the wrong direction.  I've thought through parity
comparators, but again, that leaves holes.

So what I've ended up doing is taking the outputs of the 4050 (all sixteen
of them) and shaping those into pulses rather than gates and summing them
into one continuos stream, each with a 50ms on time.

Although it took only one sentence to describe it, that function requires
sixteen transistors, 52 resistors, 22caps and 5 ICs.  In short - forget it.

Any competent PIC programmers out there who are up for a challenge?

If nay - anyone have a CMOS logic level solution???

thanks in advance,

Peter