[sdiy] ripple counters

[René Schmitz]

Hi Mark,

mark verbos wrote:
> Hi everybody,
> 
> I'm planning to build a voltage controlled delay using the Sigma Delta 
> technique, with 4164 RAMs similar to the one on Batz's page or the Delta 
> Labs stuff. I'm putting together the clocking section and I was planning 
> to use a 4040 or a pair of 4024s to count the RAMs, but I'm wondering if 
> the fact that they're ripple counters will screw the circuit up. So my 
> question is.... How long do they actually have chaos between steps and 
> is it enough to confuse the RAM in something like this? 

You have to leave sufficient time between the settling of the adress and 
the CAS, RAS and R/W strobe signals, then there should be no problem.

Obviously it
> will depend on how fast the circuit is clocked, but what is the breaking 
> point? The data sheet claims that the 4040 can go up to 6MHz. Should I 
> just use 40193s to be safe? They only claim to go up to 8 MHz. Plus, 
> they only have 4 outs each, so it will take more chips. Anyone have 
> experience with this?

I did a one chip uC-based solution to this. Check my homepage. (Home->Delay)

IMO, even if you don't have a programmer for the ATMELs at hand, 
building a simple one (couple resistors and a DB25), and then using the 
micro would be less work than building this out of MSI parts.


Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159