PT2399 with gate sequencer idea...

[mike page]

Heres an idea. The clk out of the pt2399 is divided into 1/3, 1/2, 2/3, 1 or 1 1/2
of a delay length, this is used to clk a simple shiftreg gate sequencer.
(The extra circuitry for the PT2399 is omitted in this diagram to keep it simple)

Alternatively the gate could be used to chop up the wet, dry or feedback path. Heck could chuck an R2R off of the shift reg and sequence the delay rate.

Any thoughts?

[Richarius]

I like the odd time divisions but ... we can do some of them using the CD4013 F/F's as well.
With the PT2399 though, there could be some interesting possibilities. If you breadboard it, it'd be cool to see / hear what's up, with possibilities.

[Laihal]

hey! did ou ever get a chance to build this? i have the bits to try enroute but i'd love to hear it!

[mike page]

ive built a stereo version of this and it does all the dividing and gating nicely.

theres a really annoying bug though!

Theres a hum from the 4040s that somehow gets into the audio.
The 4040s are on a separate 5v regulator to the delay.

the hum pitches along with rate modulation and if i disconnect the clock from the 4040s it stops. So I know its them. Interestingly the hum isnt present on the buffered dry input signal. So I suppose we can presume it is occuring in the pt2399 circuitry.

Any thoughts? Its really annoying because its a really cool device apart from the hum!

[Steveg]

Possibly you need more aggressive filtering.
This article about similar problems in a refurbish of a Stringz'n'things.
http://www.stefanv.com/electronics/oh-the-noise.html talks about managing the noise from an old BBD chip.

[mike page]

i found a hacky fix which worked well enough. The feedback pot on the echo circuit i used is a voltage divider. I Disconnected it from ground and the hum disappeared.