Small Time: PT2399 Delay with tails

[merlinb]

After designing the Equinox I decided I ought to build a simple PT2399 delay, much like the Rebote or DBD. A lot of people complain about the lack of tails with those two projects, so I added that too. Includes my usual full buffering, electronic switching, and 3dB quasi companding. Heavy filtering allows for useful delay times and the usual analog-ish sound, although above about 300ms you start to hear the digital hiss. You can hear it at the end of the sound clip, when all controls are turned to maximum:
Clip:  http://dl.dropbox.com/u/57831278/SmallTime.mp3


PCB layout and all files can be found here:
http://s81.photobucket.com/albums/j207/merlinblencowe/Small%20Time%20Delay/






The etching came out better on this pedal than my previous efforts. Name that logo!...

[deadastronaut]

back to the f..... ..cool etch too..

nice one merlin, fantastic, iv'e been dying to get into the pt2399's for a small delay....but with trails is brilliant!!!..thanks for your sharing man.

could we add a trails on off switch?...

[merlinb]

could we add a trails on off switch?...

Of course! I mentioned one method in the Equinox thread. Same thing applies here. Green switch is a 3PDT footswitch, and the red one is a DPDT toggle to select between true bypass and tails:

[deadastronaut]

cheers man..cool.

[LaceSensor]

son of a bitch, that looks cool.
Will hope for better results than I got with the Equinox

[jimmybjj]

Very nice, gonna have to give time one a try. How did you paint the multicolored logo?

[merlinb]

Very nice, gonna have to give time one a try. How did you paint the multicolored logo?

With acrylic paints and a fine brush. And patience...

[slacker]

Very nice.

[deadastronaut]

i gather this is not going to fit a 1590b?...125b?...

[Morocotopo]

Nice one, Merlin. Coupla questions:
It´s inverting, right? I could make the in buffer an inverting one and so it would be non inverting at the output, right?
What would be a substitute for the J112? That one is not so easy to get for me.

[merlinb]

i gather this is not going to fit a 1590b?

Huh? How big do you think it is? It's in a smaller box than the 1590b already!

It´s inverting, right? I could make the in buffer an inverting one and so it would be non inverting at the output, right?

You could do that, yes. It will be noisy.

What would be a substitute for the J112? That one is not so easy to get for me.

Anything really, except the J111. J201, or one of the 2SKxxx thingy's, whatever.

[garcho]

Bravo, I'm excited to breadboard this, thanks for the schematic. I love tails! My favorite part of using delay. Nice enclosure!

[deadastronaut]

i gather this is not going to fit a 1590b?

Huh? How big do you think it is? It's in a smaller box than the 1590b already!

i saw the 56mm pcb, and then looked at the 'eddystone 1590b'
internal width... might go in with a squeeze..
http://www.tubes.it/27134PSLA.pdf

[merlinb]

i saw the 56mm pcb, and then looked at the 'eddystone 1590b'
internal width... might go in with a squeeze..
http://www.tubes.it/27134PSLA.pdf

Ah. yes. There's room to shave off a millimetre or so from the sides of the PCB. No sweat.

[azrael]

Liking how this circuit sounds. Now, I haven't had a chance to build a PT2399 based circuit yet, but one problem I am coming across in other builds is the PT2399 locking up.
At the risk of sounding like a total n00b, is that a possibility here?

[slacker]

The locking up can happen if the resistance between pins 6 and 4, or 6 and ground, is less than 1k when the power is turned on. In this design the mimimum resistance between those pins is 1k so it shouldn't lock up.

[azrael]

The locking up can happen if the resistance between pins 6 and 4, or 6 and ground, is less than 1k when the power is turned on. In this design the mimimum resistance between those pins is 1k so it shouldn't lock up.

wheee, gonna print out the transfer today so I can build it then haha.

[robmdall]

Beautiful... Not just the enclosure, the design also. Man, I'm getting behind on builds.

bob

[earthtonesaudio]

What is "3db quasi companding"?
Nice project.

[merlinb]

What is "3db quasi companding"?

It just means that you amplify the signal  before it passes through a noisy circuit (in this case the delay line). Then you attenuate by the same amount afterwards. I pinched the term from the Stompbox Cookbook.