Stutter pedal question

[gasmask]

I would like to build stutter pedal, but I don't want to use LED+LDR / VTL.
So I found that schem: http://www.instructables.com/files/orig/F6Y/ODX1/GWF65G6U/F6YODX1GWF65G6U.png
Is it possible to use buffer (http://www.beavisaudio.com/techpages/Buffers/Buffer_OrmanTransistor.gif) instead distortion on included schematic?
Thanks for help,
gasmask

[GibsonGM]

Well, the answer is YES and NO at the same time. What is happening with the first schematic, is that the 555 timer is switching the LM386 on every time it goes high.  This creates the stutter.  The 386 also colors the sound (distortion) as you said.

You COULD modify the buffer to be switched with the 555, following the same principles as the 1st schematic, but you'll have to do some modification by experimentation.  It will not be very hard, but depends upon how experienced you are.  Try connecting the output of the 555 (pin 3) to the 9V line on the drain of the buffer, for starters, and see if it works.  The voltage will be lower (~2/3) than the 555 source, tho, so run off 12V if you can (or use a transistor to switch the voltage...see, it can get more complicated that it seems). 
Go from there, let us know if you get it working!   Your idea has merit.

[Ice-9]

One of my guitars is a Charvel model 4 which has 3 toggle switches for the pickups, which means they can all be off or on, I have found this works great if I use one pickup and toggle the switch. This direct on/off doesn't cause me any problems with switch pop so I am thinking why not just use a momentary push to break footswitch in an enclosure, or do you require a stutter that has an automatic  time control. (more like how a tremolo works).

[gasmask]

Thanks for reply,
I'm curious what will happen with sound in this situation: http://imageshack.us/photo/my-images/713/jv2l.png/

[dwmorrin]

I would like to build stutter pedal, but I don't want to use LED+LDR / VTL.
So I found that schem: http://www.instructables.com/files/orig/F6Y/ODX1/GWF65G6U/F6YODX1GWF65G6U.png

Pulsing the power on a 386 seems a bit ham fisted.  Anyone achieve good results with this circuit?
I found some testimonials on the instructables.com that said "thumping" was an annoying side effect of this scheme.
But maybe for "stuttering" a little thump is OK?
There are many tremolos that use a BJT instead of optocoupler.  Try the Schaller Tremolo.  A 555 or an opamp can replace the phase shift oscillator in the Schaller.  Just check out how the BJT is shunting the signal to ground.

Thanks for reply,
I'm curious what will happen with sound in this situation: http://imageshack.us/photo/my-images/713/jv2l.png/

If the X means you're breaking that connection, then I'm guessing "no sound" is the result.

[deadastronaut]

http://www.youtube.com/watch?v=1ej4NJSmvok&feature=c4-overview&list=UUGP0eO8ADt0H9FY5UcHTf8A

[GibsonGM]

 Sounds nice, astronaut. 

I think you could achieve exactly the same thing with a N.O. pushbutton located on your axe, as in the video, which just grounds the guitar's output signal when you push it.  No batteries required.  My personal name for that kinda thing is a signal 'interrupter', but that's just me.   You might need to do some work with a cap to prevent *pop*, but that's very easy.  Only takes a minute to test out and see.

"What's the frequency, Kenneth?"

Is this what you want to do, gasmask?  You get a lot more control than if you have a 555 pre-set (that is what we usually call more of a 'tremolo', like the Schaller mentioned above).

[Gus]

Have you looked at GEOFEX?  There is a link at the top of the page
look for "new at GEO" 10/24/03

[smallbearelec]

I would like to build stutter pedal, but I don't want to use LED+LDR / VTL.

Why not? Done right, with careful attention to layout and design of the modulator, the result is a Tremulus Lune or my Tremulous Bear:

https://www.smallbearelec.com/Projects/TremBear/TremBear.html

These are more complex, but they don't tick or thump as I am sure that Instructables design does, and they don't introduce distortion. I can tell you from experience with my Trem that it can be set for a nice, percussive stutter with control of speed and duty cycle.

If you do go the Instructables route, use the CMOS version of the 555; it's less prone to putting noise on the supply lines in designs like this.

Previous comments presume that you want an automatically interrupted stutter. If you want to interrupt the guitar signal manually, the idea of a tactile switch on the guitar is good. This one:

http://www.smallbearelec.com/servlet/Detail?no=1020

can be fitted with a cap:

http://www.smallbearelec.com/servlet/Detail?no=1060

Or you can do a stompbox with a momentary stomper:

http://www.smallbearelec.com/servlet/Detail?no=672

[gasmask]

Actually, my aim is to make stutter effect like this: http://www.youtube.com/watch?v=do8100K_rFc
or Rob's Tiny Trem, but I really want to make it simple... (VTL is very expensive in my country )

[GGBB]

Lots of this ground already covered: http://www.diystompboxes.com/smfforum/index.php?topic=102137.0

[The French connection]

a led and a photoresistor...cheap...
http://www.ilovefuzz.com/viewtopic.php?f=151&t=32044&start=15

[gasmask]

I found NSL-32SR3 which is cheaper version of VTL5C1 (used originally in Idiotbox Cyclops).
Is it possible to create the same effect using schematic from Tiny Trem v1.? Using NSL-32SR3  instead LED and LDR?

[smallbearelec]

I found NSL-32SR3 which is cheaper version of VTL5C1 (used originally in Idiotbox Cyclops).
Is it possible to create the same effect using schematic from Tiny Trem v1.? Using NSL-32SR3  instead LED and LDR?

The NSL-32xx are similar in form and function to VTLxx and are less expensive, yes. Would probably work well there, though you should expect to have to tweak LED drive current appropriately. As someone else pointed out, an LED/LDR combination is still less expensive. The problem is that not every LDR will work equally well. Preferably, you want something with high dark resistance and fast switching like the 9203 in this list:

http://www.smallbearelec.com/servlet/Detail?no=711

Part of what you pay for when you buy an assembled photocoupler is the packaging; the rest is for the known performance of the components.

[GibsonGM]

The 555 to drive the LED/fast LDR, coupled to the buffer you posted earlier, WOULD give this kind of result if you set it up correctly.

[The French connection]

Led+ LDR+ heatshrink...the circuit is so simple...breadboard it and test ldr/led combinaison that suits your 'taste'...in a dark room preferably  .
http://home.online.nl/fvrijswijk/guitar_electronics_diy/optocouplers_and_measurements/optocouplers_and_measurements.htm
Good luck.

[gasmask]

GibsonGM, so you think  it should be like this? http://img836.imageshack.us/img836/9320/ktw7.png
The 555 part is from TinyTrem...
I will breadboard it soon...

[GibsonGM]

Yes, in essence, Gasmask.   You are just allowing the signal to pass, and then not to pass, the speed of transition being determined by the reaction time of the LDR.   But be advised, you're kind of reinventing the wheel here.  About ANY already-designed tremolo circuit would work, and you wouldn't have to solve your own design problems.  You have to find the 'right' LDR for your design - but almost any will give some results you can use to get going.

That said - the issue I see with just using the LDR/LED in the signal path, which is called a home-made Vactrol - is that your input impedance will vary a lot over the range of the thing, which could affect your tone kind of strangely.  That changing input impedance could draw varying current from previous circuitry, causing it to get 'loaded down'.  That changes its frequency response.  Like turning down a tone control.

So, you have the output buffer there....I'd at least plan on using an INPUT buffer too, to allow the Vactrol to do its thing without loading down preceding circuits.   The output buffer isolates the Vactrol from the next circuit....an input buffer will isolate the stuff coming before it.

Guitar or other effect pedal >>  input buffer >>vactrol >> output buffer >> next pedal or amp

* If the output buffer were reconfigured as a basic gain stage, you could be sure to have enough volume to counter any losses, and would put a vol. control on its output. Just a suggestion.

>>>Build the 555 part and verify the LED works as you want, then build the buffer/gain stage, and replace their connection with the vactrol when ready.     Ultra-simple trem.    You can tailor this idea all you want...adjust the brightness of the LED, add a bias voltage to it, but first you probably want to make it work, ha ha.     Good experimental project and will not color your sound too much if done this way. So you can use it clean or with a distortion, your choice.