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Gate from envelope?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Gate from envelope?

I'm putting together a very small (60hp) system for an upcoming trip. I want to be able to advance a sequencer - verbos 5 step - from a looping envelope - intellijel quadra. Some modules are very forgiving as to what they will consider a gate. The verbos is not. Since the case is small I don't have access to the end pulse from the quadra expander (which advances the verbos just fine). I don't know if it's the rise time or the peak time, or zero time but the quadra envelope just will not advance the verbos. It triggers other things - nano rand, maths, among others just fine.

I know the "correct" way to do this is via a comparator but i don't have room in the case.

I've tried clipping the envelope with a zener diode, various circuits you get from googling "simple transistor switch" etc...

In my mind this should be doable and simple - shouldn't a simple transformer switch be able to be set up as a functional equivalent to a comparator?

Anyone have any ideas or guidance? Ideally it would be a circuit bump on a patch cable but failing that I could build something on the back of the quadra - there seems to be just enough room for me to drill and install a jack. Also the envelope is mirrored to the back "expander" header.

Maybe that's what you're Looking for: r.html

you can also easily test it on a breadboard or bake your own Little converter to fit into your System quickly.
Thanks, I'll give that circuit a try. I can't imagine the verbos requires a zero crossing though - then hardly anything would trigger it! But it's a great start.
doesn't the quadra also provide the EOC outputs at the back, there has been this micro expander:

otherwise, you are looking for a simple comparator, the CGS might even be a bit too complicated.

ps. and that is why everyone should have a 1u row in their case. You can then add such small circuits conveniently.
So the expander outputs are not truly an eoc, merely a mirror of the corresponding envelope. The comparator function must be accomplished on the expander board. I tried those outputs extensively.

This is hinted at in the thread but never really confirmed.

As an aside, the expander EOC seems to be actually an EOR.
EDIT: it's not either - it's a gate - high during attack, low during decay.

I may not actually have enough room to add jacks to the quadra front panel - it seemed tight but doable, today I'm not so sure.

So I may build a comparator into the case itself, sorta like having a 1u row.

My other option is to replace the 2hp Avert module with a logic module. The Or gate will function as a comparator and I can get some rhythmic funk by ANDing two envelopes. I can use attenuator cables to give me back attenuation, I'd only lose the inversion. There's a Cloud generator in the case that really requires at least attenuation of its cv inputs, if not full attenuverting.
Make a patchcord with a capacitor in series. Then it will differentiate each edge of the envelope into a pulse. Both positive and negative.

If you don't want that, add a diode in series to keep all the pulses positive.

Finally if the pulse is too high, then add two more resistors as a voltage divider to set the level you want. This should all fit in the end of a patch plug cover.

Mark the patch cord so it won't drive you crazy if you forget it's a special type. Or cut one end off a molded patch cord and the metal plug will do the marking automatically.

---------------------------------------------------------------------- ---------------
Outside of your immediate need these kinds of special patch cords can solve many problems and add capability without adding HP.

Use the same idea to make attenuating patch cords with two resistors, Use a diode patch cord to rectify, or to provide an OR function when they're plugged into a mult, or multiple inputs on the same or different modules. For example, you could have a diode in one of two patch cords feeding envelope generators, and one source will activate both, but the diode will prevent another source from activating both.

Resistor-capacitor or capacitor resistor patch cords are HP and LP filters.
A big capacitor is a slew.
The capacitor-diode cable sound perfect.

Do you have a recommendation as to size?
Just about anything will work. Would start with a .01uF
Thanks for the help. But with or with the diode, I'm not getting any luck. The verbos is being super picky about what works on its "advance" input. Looks like I'll have use an additional module to "condition" the looping envelope or try a different sequencer.
did you check what the problem is: Is the amplitude not high enough? Or the attack of the envelope not fast enough. You can vary these parameters individually and check what works.
The best way is to add a comparator to the input circuit of the verbos 5 step and make it compare to 0.5v DC. You can cut traces and add a daughter board. Don't be scared.
euromorcego I haven't been able to isolate the issue, tried all different envelope shapes and durations - no luck. I can try boosting the amplitude, but what does work is to do what I should, use an active OR gate or comparator.

EATyourGUITAR thanks, I was actually thinking about it the other way around, piggybacking a comparator to the quadra and using a 2hp module to bring those outputs into to the front.
With the solutions mentioned above, they all require the envelope attack phase to rise through some threshold before action. From start to threshold will incur a delay. Consider instead committing one channel of your Quadra in looping mode as a clock source, multing its output to the other channels with rise time zeroed.

Its also possible that the issue here is just drive. Maybe your Verbos module wants more current than the Quadra provides. A simple unity gain buffer would prove or disprove this.

Or (going under the hood)...

The quadra is generating an end of cycle pulse to retrigger itself, and that will probably be on one of the pins of the three position switch. You will probably need a scope to find this, and you may need to buffer it to drive the sequencer.
Since this pulse is end, and you want start to advance, mult this to another channel of the quadra to start a second envelope.
Thanks - i agree about the timing offset from using a threshold based test.

No, zero rise time doesn't do it. Inadequate current or "zero" time seem like the likely root causes. I'll investigate the switch pins in a few weeks but I'm outta time for this trip.
I thought he wanted the delay. if he didn't want the delay then he would have asked us for an envelope from a gate. that is just an envelope generator module. or he could be using an envelope follower with an audio input. I was not clear on what it was OP was trying to do. if all you want is clocks then the quadra is a waste of space. that should be a batumi.
The goal was to trigger the advance input on a verbos sequence selector from the rising edge of of a quadra envelope. This was for a small travel system is was putting together from extra modules I had on hand.

The quadra envelopes can trigger a great many modules just fine. Just not the one I happened to have for that case without an additional active OR or comparator module.

I needed and wanted the 4 envelopes for this one (NOT a waste of space) just wishful thinking that I could use one of its envelopes to clock the sequencer if I wanted, the way I've used quadra envelopes to clock other modules.
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