Slackers loop wiring

[DonB]

also, to anyone going by DonB's parts list, C1 should be a 10nf not 10uf.

Yes i made a mistake on that sorry.

[slacker]

Looks great GuitarTek.

[Mugshot]

just wanna share some layout i did for slacker's loop:









scale to size to print. this one fits chinese 3pdt switches.

[Yonatan]

I've been looking for something just like this.  I understand that the summing in the final stage is does with an inverting op amp configuration.  If I wanted to correct the phase of the output, could I tack on another op amp before the output cap, set up in an "inverting buffer" configuration, similar to this picture that I found somewhere (but changing -9 volts to ground, and changing ground to VB)?



Yes I know that this is an old thread, but I thought it might be better to ask my question here anyway, in order to keep the information about it all in one place.

[artifus]

http://www.diystompboxes.com/smfforum/index.php?topic=90460.0

[Yonatan]

Cool.  So aside from feedback loop, is this kind of like my suggestion to correct the phase with an extra inverting stage, except that in this case it is done before the signal gets split and then summed, rather than after, as I had suggested?  And if I'm not interested in the feedack loop, does it matter if it is done before or after?

[slacker]

No it makes no difference where you add the extra inversion, in the fancy version it's before the split because I wanted a mixer at that point for the feedback loop.

You can use the circuit you posted, you don't need the 0.1uF cap, just connect the input resistor straight to the output of the previous opamp, use 10k resistors instead of 1M, and connect the + input straight to Vb, no need for the 560k resistor.

I should really get round to building the fancy one, I drew it up then kinda forgot about it.

[Yonatan]

One more idea:  I would like to be able to turn the tailsloop on and off many times mid-song e.g. effect on for some phrases and effect off for others (but with tails of course), so I'm wondering if a momentary switch would be better instead of a latching switch for performance reasons.  How could I do that?  I came across this:

http://www.aronnelson.com/gallery/main.php/v/Processaurus/CMOS+Bypass+with+4013+debounce.jpg.html?g2_imageViewsIndex=1

But it is not exactly what I'm looking for, because in the case of tailsloop, I only need to route 1 signal (connect ground to either the effect signal or dry signal).  Maybe I could use this schematic as a base but use only 1 output of the 4053, althouth maybe this is overkill and there is a simpler way to do it.

And what is V 1/2?  Would that be the same as VREF in the tailsloop.

[slacker]

If you only want a momentary switch you can just use a momentary SPDT or DPDT stomp switch instead of a latching one. No other changes are needed.
If you want momentary and latching switches, you can adapt the wiring from the fancy feedback loop version.

Yes V 1/2 is the same as VB or vref on the schematics.

[Yonatan]

To clarify, I want to use a momentary switch to activate the effect, but I don't want to have to keep is pressed.  So I'm pretty sure that I need some kind of CMOS (to keep the on/off state) and some kind of digitally controlled analog switch.