Hi,

Thanks for the hints.

> How much accuracy do you want, and in what time increments do you want
> it to run?  (I've been out of music for a while, forgot most of it.)
>
> Could do this with a 12C509A easily, 3 pins to a shift register chain
> (with BCD coded rotary switches off the registers, so you can "dial in"
> your time interval), 1 pin to a "Read the new period" switch, pull-up to
> Vcc, 2 pins (each with 1N4002's back-biased to Vcc and ground) to a
> large Piezo disk from Radio Shack, or a speaker.
>
> On power up, read the shift registers, use a 4MHz clock so you can just
> delay 1,200,000 clock cycles for a 1.2 second period, each time you time
> out make the "click" by setting both Piezo pins to outputs, putting one
> I/O pin high and the other low, for a short while, then flipping them
> for a short while, then setting them back to inputs, you could just
> re-read the shift registers at this point (be sure to shorten your
> delay, of course, according to how long that takes!), could just check
> the "Re-read shift registers" switch at that point.  Could just use a
> 16C74 or other PCI with loads of pins and read the BCD coding directly.
>
> As most of these in the past were mechanical, you could go as far as to
> put an LCD Display on there.  That gets a little more complicated, you
> might want to set up a state machine if you go that way.  I really
> should do that state machine post some day <G>

Best regards,

Laszlo Cser