Help Building Feedback Looper

[texasisonfire]

I am trying to build a feedback looper based off this site:
http://www.ilovefuzz.com/viewtopic.php?f=151&t=16771&hilit=feedback+looper+schematic.

I tried to follow it the best I could but couldnt get it working. I took a look again and drew up this schematic and wanted to get some advice. Am I close or what changes need to be made to get this working?
My guess:
http://experimentalistsanonymous.com/board/index.php?action=dlattach;topic=2855.0;attach=1923;image


Thanks!

[Jdansti]

Howdy fellow Texan!  Welcome to the forum!

I'm not familiar with this circuit, but I see how it should work.  Your schematic appears to be the same as the hand-drawn one on the website. I noticed that you're using a stereo jack for the input, so make sure you're connected to the correct lugs. Also check for poor solder joints and any strands of wire touching adjacent lugs on any of your connections.

Hopefully you have an ohmmeter/multimeter if you still have a problem.  Make sure the switch is in the on position for all of the following tests.  Put one lead on the Send tip, and then following your schematic, check for continuity with the other lead at the Input tip and lug 3 of the Feedback pot. Keeping your first lead on the Send tip, put the other lead on the Return tip and rotate the Feedback pot back and forth. You should see the resistance go up and down. Now place the second lead on the Output tip and rotate the Volume pot back and forth. You should see the resistance go up and down.  If all of that is OK, then you have a clear signal path.

The next thing is to place one lead on one of the jacks' ground lugs and make sure you don't have continuity to any of the jack tips.

The final thing I would do is place one of the leads on one of the jacks' ground lugs and check all of the other grounds for continuity.

If you still need help, describe what it is or isn't doing and try to post a clear photo showing the wiring. You'll need to upload the photo to a photo sharing site such as PhotoBucket and get the direct link. Click the photo icon in the forum menu above where you type and insert the link between [img] and [\img]  ( I used a \ instead of / for demonstration).

Also, you should edit your duplicate post to just say "duplicate". It's confusing for the people trying to help you when there are multiple posts of the same topic. If you don't get a response to a post, just do a reply and say "bump" or "anybody?"  Thanks!

Edit: I take back what I said about understanding this.  I see now it works in the off position, routing the input through the Volume pot and to the Output jack, but when the switch is on, that path remains and the input is also routed through the Feedback pot to the Return jack. It seems like the on position should route the input through the Feedback pot to the Send jack.  The hand-drawn schematic might have the Send and Return jacks mislabeled. Try swapping the send and return cables (the external cables going to your effects-don't rewire anything) and see if that works.

Edit: After more study, the return is routed back to the send through the switch. I think me head is feeding back!

[Jdansti]

Check this schematic out. No volume pot, but one could be added.  In this one I see how the return is routed back to the send and there's no permanent path from the input to the output as there is in your drawing.



This one is more versatile, allowing you to use the send/return with or without feedback.


Well, I've looked at these long enough that I think my eyes are now permanently crossed and I've got to get up for work in a few hours!  Maybe you or someone else will be able to decipher it after looking at the additional information.

[texasisonfire]

Thanks for the insight! I'll give it a try tonight and let you know how it goes.

[texasisonfire]

So I ended up following a complete different schematic:
http://experimentalistsanonymous.com/board/index.php?topic=134.0

It sort of works, however when I switch the toggle switch, it goes from giving me feedback to no sound at all. This should act as a bypass, correct?

I followed this exactly aside from the toggle switch. I'm currently using a dpdt toggle switch and I'm not sure how this translates. Currently I have it wired like (where Y represents a connection):

XXX
XYY

Would this be accurate or how would you wire a DPDT toggle switch to match? If this is correct, any ideas when this switch is off, why there's absolutely no sound coming out of the pedal?

Thanks!

[EATyourGuitar]

Oh Hi! I learned from beavis. everything I posted is almost identical to the beavis audio schematic. I should also mention that having a non-switched volume pot is pretty useless for practical purposes. I much prefer to have the output signal routed through a volume pot only when feedback is engaged. most people can figure out how to add that in if they need it. having a vol pot always in the circuit is better for a noise board that will be operated by hand only.

[Jdansti]

So I ended up following a complete different schematic:
http://experimentalistsanonymous.com/board/index.php?topic=134.0

It sort of works, however when I switch the toggle switch, it goes from giving me feedback to no sound at all. This should act as a bypass, correct?

I followed this exactly aside from the toggle switch. I'm currently using a dpdt toggle switch and I'm not sure how this translates. Currently I have it wired like (where Y represents a connection):

XXX
XYY

Would this be accurate or how would you wire a DPDT toggle switch to match? If this is correct, any ideas when this switch is off, why there's absolutely no sound coming out of the pedal?

Thanks!

Your link has several schematics on the thread. Which one are you using?

[texasisonfire]

Sorry, I mean this most recent link from Experimentalist Anonymous. I suppose it's not so much a schematic as it is a walk through.

This:
http://experimentalistsanonymous.com/board/index.php?topic=134.0

[Jdansti]

If you're using a DPDT switch instead of a SPDT for the Feedback I/O switch, then you would just use 1/2 of the switch. A way to check to see your problem is somewhere else is to take the two wires and remove them from the switch. Short them together to simulate a closed switch and leave them unconnected to simulate an open switch. If your pedal works when you do this, you either had the switch wired wrong or the switch is bad. Otherwise, you've got a problem somewhere else.

[ashcat_lt]

In mine I opened up the feedback pot and cut the track at the "zero" end of the pot.  No toggle necessary.