Rick's Attack/Release Generator - a fun little add-on.

[frequencycentral]

Here's a fun little circuit. It's an attack/release generator, synth stuff really, but could make a fun little add-on for any number of effects.

The two nodes marked 'to pot' can be hooked up in parallel to whatever pot (which is configured as a variable resistor) on whatever effect you choose. I've given the value of the Depth pot as 100K, though what you would really want to do is double the value of whatever pot you are using the A/R Gen to effect, and use that same value for the Depth pot too.

It's designed to be actuated by a footswitch, either momentary or latched. When the footswitch is actuated, the LED will slowly brighten, the time it takes to brighten is set by the Attack pot. When the footswitch is un-actuated, the LED will slowly dim,  the time it takes to dim is set by the Release pot. The LED controls the resistance of the LDR. The Depth pot defines the depth (!) of the LDR's effect on whatever you choose to hook it up to.

Applications? C'mon, use your imagination! I know what I'll be using it for.........

[Earthscum]

I DIG! I was just reading the boards before I went and built my bass synth curcuit to tweak on for a bit... it's a solid 0.4V peak to peak output at any pick attack, and I was just thinking of some ways I could add in some dynamics.

Super kewl! +1

[Brymus]

So the first thing that comes to my mind is some kind of programable sweep on a phaser or flanger.
How about on a tremolo pedal? You could have the effect speed/slow by hitting the footswitch.

Where did you get this idea Rick?
Really cool.

[bean]

This looks great, Rick. I've been wanting something like this for a while. I can think of some fun to be had with delay, too.

Any particular reason for choosing the TL084, or is it just what you had on-hand?

[BadIdeas]

I'm not sure what I would do, but since the footswitch appears to be single pole, maybe use multiple A/R's in one pedal. Maybe adjust drive and tone simultaneously in an overdrive circuit? Maybe force an auto-wah to to gravitate toward treble or bass, even when playing dynamically opposite lines. Of course, at this point you might use a treadle wah, but if you are also using it for rhythm and don't have good timing in your feet, it may be useful. It could also be used in other envelope controlled effects for similar reasons.
You mentioned putting it across a variable resistor, but wouldn't it also work from one lug to the wiper on a voltage dividing pot?

[frequencycentral]

I put this circuit together a few years ago for a little synth I built. It's a really simple envelope generator inspired by similar circuits in the ARP Odyssey (which uses transistors instead of opamps) and the Octave Cat (which uses CMOS instead of opamps). I used a TL084 because I've got dozens, though in the past I've used LM324 for variations on the same circuit. Just about any opamps should work, I just prefer to use quads rather than two duals.

I'm planning to use it in parallel with the delay time pot of a PT2399 based delay. This will give the ability to select between two different delay times, as well as defining the speed of the 'swoop' between the two. With a little more work it could be used to gradually introduce modulation too.

Yeah, it would also work across one half of a voltage divider pot I guess. I'm quite sure there are many more applications that I haven't thought of.

It might also be fun to box it up as a standalone controller and use the ring and tip of a TRS to connect it to whatever device one wished to equip with a suitable input.

[Hides-His-Eyes]

Would be great on a trem

[bean]

Delay modulation was the first thing that came to mind for me...delay time too would be wicked. I think for a stand-alone controller maybe it would be better to use a smaller hook-up, like 1/8" jack...or maybe an RCA? This might make it easier to connect to other effects where space is limited to insert a full TRS jack.

How about the Belton reverb brick? Maybe to control reverb or modulation swells. A lot of possibilities here!

[BadIdeas]

I was just looking at a Fuzz Factory layout. I'm not sure if it's right, but the Stability pot looks like a fun target. I'll have to look up some YouTube demos.
I'm sure all kinds of old dusty pedals could be resurrected by this new animation gizmo.

[Strategy]

Tim Escobedo's "Q&D VCF" is just asking for add-on's like this!

[frequencycentral]

Ok, a few developments. It occured to me that both momentary and latched footswitches would both have their uses. So I decided to use a 4013 flip flop to switch states using a momentary switch. Special thanks to earthtonesaudio/Alex for suggesting the debouce circuit and streamlining the design in general.



So.........here's what it does:

Initial state = off

   * quick press >>> latched on
   * quick press >>> latched off
   * long press >>> on until released, then off

Initial state = on

   * quick press >>> latched off
   * quick press >>> latched on
   * long press >>> off until released, then on

So a quick press forces the flip flop to change states - ie a latched switch. A long press allows the 10uF cap to discharge - ie a momentary switch. A quick press lasts about a second. Anything longer is a long press. Really useful to have the option to initiate momentary or latched actions dependent upon how long you hold the footswitch.

In addition to the LED to drive the LDR, there is a LED to indicate the state of the flip flop and another to show the rise/fall of the A/R Gen. Both these LEDs need their cathodes to be connected to vref, not ground.

Here's the artwork, unverified, but I hope probably correct.