Slackers loop wiring

[DonB]

Cant seem to get the loop wiring to work. Was wondering if you could use a 3pdt switch like the below pic
Something like this

[slacker]

No that won't work, if you want to use a 3PDT then it just replaces the DPDT, like this.



Connect the sleeves of all the jacks together and then connect a wire from one of them to the ground wire on the vero layout. If you're using a battery to power it, connect the negative, black, wire of the battery snap to the bottom row on the layout, or if you've used a stereo input jack connect it to the ring of the jack. Connect 9 volts to the positive, red, wire from the battery snap. If you're using a power supply then connect a wire from the bottom row of the layout to the ground pin on the DC socket and connect 9 volts to the positive pin on the DC socket.

It's probably best not to keep starting new threads about the same thing it just makes it harder to follow what's going on just keep posting questions in the same thread.

[DonB]

Ok thanks again Slacker.
I have got it to work bypassed now. But no when engaged, so need to do some debugging i think.

[DonB]

Im having trouble understanding how this switches from bypass to loop.

All circuits i have seen so far go from input tip to switch to board input. Board output to switch to output tip.
Im probably wrong but i dont see where the switch changes to when pressed?

Looks like when you press the switch it either grounded it or ungrounded?

Also can it be connected so tails is always on instead of having the 2 way switch?

[DonB]

I have verified that the circuit works. But the output when loop on is only audible when the battery ground is on the input or out put jacks tip (but distorted). I have been through the wiring 100 times. its all correct.

[slacker]

Im having trouble understanding how this switches from bypass to loop.

The schematic might help explain it, this doesn't have the tails/no tails switch but apart from that it's the same as the layout.



The first omp section buffers the signal. The signal then splits, the bypass signal goes though the two 47k resistors to the second opamp section. The signal also goes through the two 1k resistors to the send, then via the the return to the second opamp section. The second opamp section mixes the signals together and sends them to the out.
When the thing is in bypass the switch, that's the thing between the 47k and 1k resistors, grounds the point between the two 1k resistors, so no signal goes to what ever is in the send/return loop. The signal can only go through the two 47k resistors so all you hear is the bypass signal.

When loop is selected, the switch grounds the point between the two 47k resistors so you don't hear the bypass signal. The signal instead goes through the two 1k resistors to the send, so you hear what ever is in the loop.

When you then switch back to bypass, you hear the bypass signal and the signal stops going to the send, but what ever is already in the pedal in the loop still goes through the return so gets mixed with the bypass signal. This is what gives the delay tails.

This is why the wiring isn't like on most pedals, the output of the loop needs to be connected all the time so you can hear the tails. Normal, true bypass wiring disconnect both the input and output when bypassed so you can't mix in the tails.
 

Also can it be connected so tails is always on instead of having the 2 way switch?

If you only want tails remove the 2 way switch and the wire to it from the right hand side of the board. Connect the wire that was going to it from the left hand side of the board to the 3DPT, where the wire going to the middle lug of the 2 way switch was.

[slacker]

I have verified that the circuit works. But the output when loop on is only audible when the battery ground is on the input or out put jacks tip (but distorted). I have been through the wiring 100 times. its all correct.

Is this with the proper wiring of the 3PDT?

[DonB]

It is with your wiring that this happens. I have tried other was, but as you mention above it doesnt work unless wired your way. But i still have nothing in the loop?

[DonB]

Just wondering...

Im using an 4558 ic. Could i have put it in wrong? i put it with they little half circle in it at the top?

[slacker]

Yeah the circle goes at the top, if it works in bypass with the proper wiring then the 4558 must be in the right way, if it was in wrong you'd get no sound and probably smoke from the 4558.

Crap, I've just noticed there's an error on the layout, there should be a trace cut in the space next to the bottom of C4. Cut that and hopefully it will work, sorry for not noticing that sooner  

[DonB]

Between the jumper and C4 you mean?

[slacker]

Yeah

[DonB]

Thanks Slacker...Works fine now. Glad you noticed the missed track cut. This was doing mu head in...

Love this one.

[DonB]

How do you make the vero pics...It will need to be updated with the cut.

[DonB]

Doesnt matter i used paint to fix it...

Here it is Fully Verified!!!

[slacker]

Excellent glad it works, I was just writing you some instructions on how to debug it when the missing trace cut jumped out at me.

Thanks for fixing the layout.

[DonB]

You are most welcome. Thank you for all your help with this. I dont understand schematics properly so i would never have found the problem myself. Also thanks for all the wiring troubles i put you through.

[DonB]

I am interested in making this into a pcb. Anyone have any idea how to do this?

[arma61]

Hi

I'm working on it just now, if you have ExpressSCH and ExpressPCB I can send you (and anyone else ) the files when I'm done. Though I'm not an expert in this..... 

looks like this atm

[arma61]

@Slackers, how does it behave in a TrueBypass chain?



Thx
Armando