Single press 'Looper Stop'

[rogs]

I have a singer/guitarist friend  who uses a 'TC Ditto+' looper pedal to play his backing tracks. Works well for that task..
 
What he dislikes though is having to press twice to stop the device.... So I built him a simple interface to allow an external footswitch to be pressed once to start the looper track, and ONCE to stop it.
Couple of 4000 series CMOS logic devices, a few passives and a bit of stripboard.... Sorted!
 
What did surpise me was that I couldn't find anything  - either DIY or on the market - that did the same thing . There are some 2 switch loopers which have a dedicated stop switch -- but they don't have the 99 locations and the 60 minute record time that the Ditto+ does....

I have heard people talking about using an 'Arduino' to create this kind of project, but that seemed overkill, for a simple task like this?

Anyway, if anyone's intersted, I made some project notes and posted them here: www.loop.jp137.com
The construction is 'classic' 'stompbox stripboard' !   

[PRR]

> Couple of 4000 series CMOS logic devices

CMOS??? What is this, the Age Of Disco??  (asks the guy with two cars old enuff for Antique plates, but not qualified cuz we drive them weekly.)

Useful idea, looks well considered. But:
https://www.loop.jp137.com/index-onesw.html  note; onesw.html
"The schematic above shows the two switch version..."  < typo?

[RickL]

This is exactly what I've been looking for. Thank you! It has the advantage, for me, of being able to locate the pedal itself high enough that I can adjust the playback volume without bending over. I expect this would be handy for loopers that allow storing multiple loops as well.

How does the loop erase function (press and hold switch) when either of the two versions are used? I am imagining that simply holding the switch on the single switch version or holding the main switch on the two switch version would erase the loop and set the pedal to start recording again when the switch was tapped again.

[rogs]

> Couple of 4000 series CMOS logic devices

CMOS??? What is this, the Age Of Disco??  (asks the guy with two cars old enuff for Antique plates, but not qualified cuz we drive them weekly.)

Useful idea, looks well considered. But:
https://www.loop.jp137.com/index-onesw.html  note; onesw.html
"The schematic above shows the two switch version..."  < typo?

Thanks for the heads up -- it was indeed a typo (now corrected!).

4000 series CMOS ? --- most versatile set of chips ever -- function selection, DC supply range, low power etc.. ..  (All in IMHO of course! )
 
These days every project seems to begin with the words 'what you need to do that with is an Arduino' -- (or a PIC or a Raspberry pi) etc,etc, when in many cases some good old fashioned 4000 series CMOS will get the job done!
I remember reading in a Philips data book -- in the late 80s - that 4000 series 'should not be considered for new design'.. Fast forward over 35 years and you can still get them. Some devices have carried on into a new life with SMT.
So I'm not the only one still using them, I suspect? 

[rogs]

How does the loop erase function (press and hold switch) when either of the two versions are used? I am imagining that simply holding the switch on the single switch version or holding the main switch on the two switch version would erase the loop and set the pedal to start recording again when the switch was tapped again.

Note: This post has been significantly edited since its first draft......hopefully to clarify the points raised a bit better.

The 'one switch' version is designed just to control playback.
Pressing the switch the first time will generate a single 50mS pulse, regardless of how long you hold the switch. Releasing and pressing again will generate 2 x 50mS pulses to stop the pedal - again regardless of how long you hold the switch on. So it can never enter the erase mode.
In the 'one switch' version you would not have any input connected to the looper, so If you were to select an 'empty' slot by mistake, pressing the switch would generate a pulse and start to record. Of course with no input connected, nothing would be recorded.
I imagine you'd pretty soon realise your mistake and stop the unit. If you did want to erase that 'blank' recording immediately, then the switch on the Looper is still functional, so a long press on that would erase the 'silent' recording. That is the only way to generate a long 'erase' pulse with the 'one switch' version.
Probably not really necessary during a live performance (I can't see anyone letting a blank recording being run for any length of time, so no significant memory will have been used up?).
If you were to try and play that location again without erasing, it would simply loop round in silence.

With the 'two switch' version then the main switch simply copies all the functions of the Looper switch, and the second switch acts only as a single press stop. (That second 'stop' switch only works when the looper is actually running). So when pressed and held, the first switch will remain 'on' for as long as it is held. As I say, it simply mimics the looper switch
The second 'stop' switch is only able to generate a 'double 50mS pulse' when looper  is running......and once pressed, It will not work again until the looper has been restarted by the main switch.

One slight disadvantage with this simple interface is that it has no way of knowing if the looper switch has been pressed or not.... So it might require two switch pushes, if a press on the actual looper switch has put things 'out of sync'.  There is no need for the looper switch itself to be activated at all with the 'two switch' version.

To avoid any problems like this my friend has fitted a small metal 'clothes peg' onto the actual looper switch, to prevent it functioning at all.  Avoids mistakes on stage!
He was tempted to fill all the unused slots with short blank reordings to completely avoid the accidental empty slot record problem, but the Ditto+ has 99 addresses, so that might be over the top.

As I say, it's  only a simple interface that attempts to deal with what seems to be quite  a common complaint -- and only cost around £20 to build (about half of which is the enclosure cost).
Introducing the looper switch itself into the logic, to try and deal with obscure operator errors would move everything up a gear, complexity and cost wise.

A project for someone keen on using a microcontoller perhaps ?

But as I say, the 'two switch' option means the looper switch itself never needs to be pressed.

 

[PRR]

CMOS ? --- most versatile set of chips ever

I maintained a tape-deck with a "computer" that was not RPi or Arudino, or LSI, or CMOS, or even TTL, but all RTL. It may even still be running somewhere. (If you are curious, Don Lancaster wrote the DIY cookbook.)

[rogs]

Just a quick heads up to say that my reply to RickL in post #4 above has been heavily edited since I first wrote it.... Hopefully it now explains the operation of the 2 versions a bit better....