[sdiy] Binary state change detector

[Peter Grenader]

re: synchronous.

can't.

OK, here's the application:

Milton has the ability to react synchronously or asynchronously to it's VC
Input.  Synchronous is cool and has its applications, but asynchronous is
REAL cool because you get the added benefit of a certain amount of
expression gained by non-linear advancement, such as from a sine wave
driving the circuit.

Problem is, when the async is thrown in, the user looses all syncing.  I
need a way to extrapolate a sync pulse based on the logic changes going into
the 4516 counter from the A to D, because at that point that's the only
thing driving the sequencer as the incoming clock is taken completely out of
the circuit.

I tried using a frequency doubler on the MSB of the A to D, but the R/C is
too dependant on the frequency of state changes and it was hard to find one
circuit that could react accurately across the entire expected operating
range of the sequencer.  So, I figured the only reliable way to do it was to
sense the state changes themselves and not an R/C to derive a phantom clock
as the doubler attempts to do.

- Peter

 Czech Martin wrote:

> if it is all clocked, why don't you use a clocked FF
> to hold the information. This is ok as long as you can make
> up for the additional delay of one clock, which is possible
> for many applications.
> 
> Why build some asynchronous logic when synchronous stuff
> will do the job?
> 
> m.c.
> 
>> -----Original Message-----
>> From: owner-synth-diy at dropmix.xs4all.nl
>> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Peter Grenader
>> Sent: Mittwoch, 8. Oktober 2003 16:21
>> To: Synth DIY
>> Subject: [sdiy] Binary state change detector
>> 
>> 
>> I am looking for a circuit that detects when the state
>> (number) of a  four
>> bit binary word changes state.
>> 
>> I've been putzing around with the idea of using a 74C85 in
>> conjunction with
>> a 4242 (using the 42 to latch the the last occurrence of
>> change and feed it
>> back into the C85 for the next comparison, and then running
>> that output
>> through a oneshot to keep it from disappearing as soon as it
>> is sensed, but
>> to this I have a question:
>> 
>> How short of a incoming pulse does a oneshot require in order
>> to react?  For
>> instance, another perfect example is a sequencer reset pulse
>> coming from one
>> of it's stage gate outputs.  As soon as it goes high, the
>> reset function
>> occurs and the gate is no longer high.  Will that pulse
>> width, as short as
>> it is, be long enough for a oneshot to react?  Although this isn't my
>> application, its the same idea and if it's long enough, me
>> thinks I've got
>> the circuit I need here.
>> 
>> If not, I'm totally screwed and am asking the masters here if
>> they have any
>> other suggestions.
>> 
>> thanks in advance,
>> 
>> Peter
>> 
>> 
>