The Feedback Loop Schematic

[telecashew]

http://experimentalistsanonymous.com/diy/Schematics/Buffers%20Switchers%20Mixers%20and%20Routers/Feedback%20loop.gif

This looks relativly simple and cheap to make. I just have a couple questions: What do each of the rectangles and the big circle thing represent, and where would the ground wire connect to? Also, how would I go about housing this thing (I've never built anything before)?

Thanks Colin!!!

PS: Just so I'm clear, a feedback loop will make an effect sound kinda oscillated and make crazy sounds, correct?

[expanoncolin]

http://http://experimentalistsanonymous.com/diy/Schematics/Feedback%20loop.gif

This looks relativly simple and cheap to make. I just have a couple questions: What do each of the rectangles and the big circle thing represent, and where would the ground wire connect to? Also, how would I go about housing this thing (I've never built anything before)?

Thanks Colin!!!

PS: Just so I'm clear, a feedback loop will make an effect sound kinda oscillated and make crazy sounds, correct?

The rectangles are the lugs or connectors of the pot.  The ground wire is basically just conneted to one another on the jacks.  House it inside of any old aluminum box you can find.  Start big if it's your first project, it's easier that way!

-Colin

[telecashew]

So what's the difference between the pot with 6 lugs than the one with 3 and the circular one? Also, is it supposed to have 4 inputs/outputs (Input, Output, Send, Return)?

[expanoncolin]

So what's the difference between the pot with 6 lugs than the one with 3 and the circular one? Also, is it supposed to have 4 inputs/outputs (Input, Output, Send, Return)?

The one with 6 lugs is a DPDT switch, the one with 3 is an SPDT switch, and the "circular thing" is a potentiometer.

Yep, 4 jacks.

-Colin

[telecashew]

Ok lets consider this (poorly drawn) diagram. The Input/Output is for the guitar chain right? Then you put the pedals that you want in the loop through the send/return right? Ok, then the pot controls the mix of the loop? The DPDT is the TB stomp switch but I'm not really sure what the SPDT switch is for...would it be a toggle switch? But what would it do?

Ahh, sorry Colin! You're probably fed up with me hehe. (Stupid Newb)

[expanoncolin]

The SPDT could be a toggle or a pushbutton,  either way.  It would determine whether it was a feedback loop or just a true bypass loop.  The knob isn't a mix knob, it's a feedback amount knob.

We're all newbies at one time or another

-Colin

[telecashew]

hehe yay! Thanks Colin, your awesome. So this thing is completley passive right? No use for a battery? I'll be making this thing quite soon, I just need to buy the supplies I'd say it'll be about a $10-$20 project?

[expanoncolin]

hehe yay! Thanks Colin, your awesome. So this thing is completley passive right? No use for a battery? I'll be making this thing quite soon, I just need to buy the supplies I'd say it'll be about a $10-$20 project?

Yep, totally passive... let's see, for supplies-

$10 for a case
$6 for a DPDT
$1 for the SPDT
$4 for the 4 jacks
$1 for the pot

That's $22 total, not including the soldering iron, solder, and wire if you don't have it yet.

-Colin

[telecashew]

Awesome, I'm definatly gonna start this project in the next month or so. I'm swamped with so much school work its not funny   Anyways, thanks again Colin. You are teh mast0r. I'll probably update this thread when I start building it.

EDIT: Do you have any pictures of a home made feedback loop like this one? I'd like to see some examples and ideas. OH! and another question. I would probably be interested in painting it or somthing of the sort. Is there special paint to buy like model paints or spray-paint?

[CrackityJones]

ok so ive been looking to create this feedback loop as a first project for sometime, but i cant find any suppliers in britian where i can get the inputs, although i suspect ive not really searched correctly for them, but my main issue is that i cannot find any dpdt stomp switches, i can find toggle ones, much as they would do the same job its sorta impractical. anyway so my main questions, does anyone know of suppliers in britian where i can get the parts needed for effects projects, such as dptp stomp switchs and inputs as i cant find anywhere?
also, what resistance value of pot do i require?

thanks

[expanoncolin]

Smallbear ships to the UK.  So does http://www.maplin.co.uk

-Colin

[schism]

so, i have my feed back loop, now is there any way to be able to use an expression pedal instead of the box mounted pot for a mix control? schematic would help... thanks. do i just use a stereo jack in place of the pot?

[expanoncolin]

so, i have my feed back loop, now is there any way to be able to use an expression pedal instead of the box mounted pot for a mix control? schematic would help... thanks. do i just use a stereo jack in place of the pot?

Yes, but keep a few things in mind...
1) Because the pot is such a large value, it won't work with expression pedals (which are commonly 10k).  You will need to buy an empty wah or volume or expression pedal and put your own pot in there.  There is a detailed tutorial on this in the Articles/tutorials board.
2) Because the pot is wired as a variable resistor (2 pins, not 3) it only need to be a mono jack... however, I personally prefer using stereo jacks and using the shaft or shield conductor as a ground as usual to prevent the strange and bad effects that happen because if you use a metal jack the shaft conductor is automatically touching the case and you can create stray resistances from your hands by mistake.  Or you can just use plastic jacks on either end.

Please post pics on that thread when you do it...  Good luck.

-Colin

[schism]

i put a jack in place of the blend knob, but nothing happens. i am using a volume pedal with a 500k pot and the only time i get any action is with the heel all the way down. and its nothing but maxed, loud, shrill feedback. ive tried wiring the lugs on the jack differently, but to no avail.  any suggestions?  

the pedals i was using were a pm7 and an old yamaha eq.

[Hot_Rats]

i put a jack in place of the blend knob, but nothing happens. i am using a volume pedal with a 500k pot and the only time i get any action is with the heel all the way down. and its nothing but maxed, loud, shrill feedback. ive tried wiring the lugs on the jack differently, but to no avail.  any suggestions?  

the pedals i was using were a pm7 and an old yamaha eq.

you need to substitute a smaller pot value.
and, I hate the small stone in a feedback loop. i get nothing but the sounds you desribed. really loud really shrill. im guess most phasers do the same. take the phaser out and see if you have any control over the EQ's feedback.