Payback v1.1 Layout!

[Valoosj]

It just has one small issue. When in bypass you hear a squeeling sound in the background and you also hear this for less than a second at the beginning of each loop (probably because a fraction of it gets recorded.)
I am already posting this since the pedal does its job other than this little mishap. Hopefully someone will be able to tell what the problem is.


At pin 14 of the ISD you have to add the correct resistor and hook it up to ground. Or put an external clock there for modulation.
At the moment I have a 100K there.
The reason for 2 ground paths is that The Tonegod suggested this to kill the problem, which it did not.

[Valoosj]

Oh right, the schematic would come in handy 

http://www.geocities.com/thetonegod/payback_v11/payback_v11.html

There is one mistake in the CD4093, some pin numbers are not correct here but they should be in the layout.

[xshredx]

Where did you find the isd1616?
Looks like a cool project, but I cannot find that ic...

[Valoosj]

I got it about 1 year ago. I have six and can't find any more. Wish someone could help me debug this sucker though. Tonegod doesn't reply to his pm so I guess he's busy.

[Papa_lazerous]

the 7805 regulator could possibly causing some noise, I cant see any caps on either side of ti to keep it all happy and stable like you should.......

[Valoosj]

Ok I'll give that a try. Any prefered values? I'm thinking somewhere above 100uF should do the trick.

[kurtlives]

Ya 100mF before and after would be fine. Might also want to add a 47nF too, filters out an RF.

[kierc]

Sounds like a good project, anyone know where to get the ISD1616B or ISD1620B though?

[Papa_lazerous]

I'm tempted build this myself.......I'd probably redo the layout though.  Not taking away from yours I think you went as far as you can with the software you used.  I'll draw it up in Eagle later tonight and see if I can come up with something thats got less tendancy towards noise if anyone is interested I'll share

[Valoosj]

I took this layout beyond the normal software and added traces with paint. The reason for doing this is that I want to fit it inside a B size enclosure.
I would be very interested in a layout that can fit inside it and have less noise. Although I still have to try the filtering on the regulator, that might make it work.

[The Tone God]

Sounds like a good project, anyone know where to get the ISD1616B or ISD1620B though?

From what I have heard they are not going to be making the DIP versions unless someone makes a large order probably in the thousands. I only bought one when I was designing v1.1 but I am beginning to wonder if the values only work for my 1600 and others vary enough for those values to not work. I can still get SOIC versions so I may get a couple of those and do some more testing to  find out whats going on.

I am almost ready to abandon v1.1 and just focus on v2.0 in progress.

Andrew

[Valoosj]

It's not that it does not work. The pedal works fine as designed, but I get a his/peep or whatever during bypass. I am getting ready to solder as I type this message. The plan is to attach 2 100uF caps to the regulator. Maybe that does the trick. If it does I would really like to get my hands on a few more ISD ICs. Even if that means SMD and having you order some extra 

[Valoosj]

HOLY CRAP! It did the trick! No more noise issues. Now I only wonder: is it normal that when I touch the start stop knob with my fingers that it stops playing? You once mentioned to me that this was due to the diode trick.

[Papa_lazerous]

Glad to hear the noise has gone, thats one thing sorted

[Valoosj]

I'm setting it up in a test enclosure to see it the footswitch has issues.

[The Tone God]

HOLY CRAP! It did the trick! No more noise issues. Now I only wonder: is it normal that when I touch the start stop knob with my fingers that it stops playing? You once mentioned to me that this was due to the diode trick.

Oh so it is looping now ? The diode is sensitive to touching and even how the wire routed. Just the nature of the beast so just be alittle careful of  how you do the wiring. Not a big deal though.

Andrew

[Valoosj]

It always looped. Now it works fine. You get some background noises during the playback, but it's lofi so that must be normal. Nothing substantially loud either.

However, I cannot touch the enclosure or the playback will stop. The tone regulation acts more like an extra volume knob as well. These are some minor issues probably.
How would I go about the wiring of the diode thing then to avoid this contact problem? Any tips on that? I'm getting very close now!

[The Tone God]

However, I cannot touch the enclosure or the playback will stop. The tone regulation acts more like an extra volume knob as well. These are some minor issues probably.
How would I go about the wiring of the diode thing then to avoid this contact problem? Any tips on that? I'm getting very close now!

Oh I thought the looping problem had resurfaced. Good to hear. You can change the tone cap to a smaller value if you think it cuts too much. Keep the wiring around the diode away from things like ground connections and even the case itself. The diode is acting similar to a weak pullup resistor.

Andrew

[Valoosj]

Hah ok wonderful! It works!

If you could get your hands on some more ICs, I'd love to have a few

I'll rework my layout to tackle the final issues and experiment with the tone control.

Thanks for this wonderful project and the help on debugging the layout Andrew. 

[Papa_lazerous]

Do you fancy posting some sound clips of it in action?