LDR transistor gain

[EBK]

And yes, the downward moving Q-tron filter is my least used, unless I'm playing some funky reggae fusion, which I did a couple of times, confessedly.

It makes more sense to me now. Sort of like a fake slap bass sound?

[Kipper4]

Haven't read all the replys yet.
I will try to clear up the signal paths.

enveloped signal= the buffer signal with the envelope detector controlling the ldr/R17 voltage divider and therefore the gain on the ltp's left input.

buffer out= the input buffers dry signal to the ltp's right input.

I'm hoping some how to cut as much of the compressed signal noise and make a swell on the note/chords decay.

This thinking and hoping thing hurts my little brain.

I've had reasonable success with cleaning up the compresser noise on the breadboard over the last few days. By adding a weaker then input buffer level dry path.
It's not an ideal solution for the type of thing I have in mind since really by mixing in some dry signal you get the string pluck noise.
hhhhhhhhhmmmmm
It's not saying            "Is that a violin?"  to me yet.
So I'm gonna do my dammed best to find some alternative solutions.


I go read.

[robthequiet]

And yes, the downward moving Q-tron filter is my least used, unless I'm playing some funky reggae fusion, which I did a couple of times, confessedly.

It makes more sense to me now. Sort of like a fake slap bass sound?

Yep, and I realize that I mixed frequency filter with amplitude -- but yeah, something that would act as a palm mute pedal, or a reverse swell that turns around and swells up again if you have a long release.

[Kipper4]

There in lies another dilema. Keeping the swell time short. long is not usually a problem.

[EBK]

enveloped signal= the buffer signal with the envelope detector controlling the ldr/R17 voltage divider

That's the part I didn't understand before. Thanks for clearing it up for me. 

[Kipper4]

I'm wondering now if the ltp is worth persuing.
Opinions please.

[EBK]

I'm wondering now if the ltp is worth persuing.
Opinions please.

I'd use an op amp instead.

This circuit looks interesting:
http://www.dirk-hendrik.com/temp/dod_fx15.pdf

Of course, you'd be replacing all that stuff in the upper right with appropriate envelope following and reshaping stuff.

[robthequiet]

I would vote with Eric on the ltp, bcs essentially in an op amp you get diff amp architecture on 10 cups of coffee, so let the chip do the stabilizing circuitry for you. Is the BMP-type collector-base feedback resistor still an open question or did it not pan out? But for research purposes it might be worth a shot to see how much modulation you get. A regular BJT amp with AC-coupled modulation seems scientifically the same, to this a non-scientist, albeit well-coffeed.

[Kipper4]

I'm wondering now if the ltp is worth persuing.
Opinions please.

I'd use an op amp instead.

This circuit looks interesting:
http://www.dirk-hendrik.com/temp/dod_fx15.pdf

Of course, you'd be replacing all that stuff in the upper right with appropriate envelope following and reshaping stuff.

reshaping stuff. That's where i come a cropper.
I have recently recived a document with some shapers maybe one of those will do. Otherwise I'm looking for guidance and learning on the shaping thing please.

Much appreciated
I'll have a go at some of the extra stuff in the schematic though.
cheers
Rich

[Kipper4]

Can this be adapted to +9v bipolar power supply and work well with guitar?



http://www.muzique.com/schem/2720-11.gif

[EBK]

Sure.  It's basically an envelope follower with a comparator, right?
Take a look at this somewhat similar circuit:

[Kipper4]

Ok so I managed to cludge together a trigger thing that kinda works how I want it to from the previous post.
The thing is I don't get how it even works.
If it's a rectifier. What kind.

How come the led still lights up despite the C15 DC blocking cap.

[EBK]

That's a precision full-wave rectifier.

Your cap blocks DC, but it is better to think of this as a "recentering" around 0V.  After that cap, there are positive voltage portions of the waveform that are pulsing your LED on.

[Kipper4]

Thanks Eric
This rectifier arrangement could have other envelope uses.

Dont get me started.

How can I tweek the  "precision full-wave rectifier." ?
I already made R14 220k and It wasnt as functional.
tried 68k too.

I guess R22 22k sets the gain of the first op amp IC3-B

[Kipper4]

Now It's getting useful.

[Kipper4]

I should have known the precision full-wave rectifier.
I'm that used to using half wave fig 3

http://sound.whsites.net/appnotes/an001.htm

I guess what I did with the swell knob was control the amplitude of those," positive voltage portions of the waveform."


"After that cap there are positive voltage portions of the waveform that are pulsing your LED on."

Igor I have work to do..........

[Kipper4]

http://www.play-hookey.com/analog/feedback_circuits/full-wave_rectifier.html

Great little article for the intrested.

[EBK]

You may want to take a look at the Fig. 6 circuit in that Rod Elliott page you cited.  It has (potentially) higher input impedance for one thing (depending on what you choose for R1).

[Kipper4]

I should have said the input is buffered.
I've swapped to an op amp buffer too.
I'll go look thanks Eric.


Back.
The diode orientation is a little different. At least it still has a positive output.

[EBK]

 Unless you need it for another reason, you could get rid of the buffer if you use that Fig. 6 circuit.