Stereo Stutter Stombox

[beto]

Hi Everyone, I'm building a Stutter box based on the 555 chip and till now it goes fine. I have posted a sample video of the prototype

http://www.youtube.com/watch?v=f2Tq5HMMSfc

I have sent the 555 output to a led that is enclosed with a shrinking tube with a photo resistor connected directly to the guitar jacks. I based the design on the great article in beavisaudio:

http://www.beavisaudio.com/projects/StutterPedal/index.htm

I was wondering if I'm doing that ok, or if it's a better way of achieving this (led + photoresistor).
About the stereo feature: what would be the simplest way of doing that in stereo? One quick way is to do the same with the remaining led that is in synch with the one with the photo resistor. I would also like to know what pots would you use for frequency & stereo paning.

Thanks in advance

[edvard]

Your idea is probably the simplest, kudos for making it work so well, sounds nice.
As for stereo, I think you're on the right track.
What might make for interesting stereo effects is to have TWO of these units in the same box so you can have diffferent timings go to different speakers.
Trippy...

[cloudscapes]

having seperate 555's for right and left could be awesome! you could have a master speed pot for both and an additional "drift" pot to offset the speed between the two. it would sound nuts on headphones!

[a soBer Newt]

you could also use a cmos inverter to flip the signal on the opposing channel

[beto]

Hi everyone! thanks for the answers!
I would definitely try the two 555 idea. I haven't seen something like that before, and for sure won't be difficult to mount it in the breadboard.
About the stereo feature CMOS inverter seems to be a good idea, I have never used one of those before.

I have been doing some experiments and one interesting thing is that If you ground the signal (beavis audio schematics) then the sound is very different than if you directly disconnect the input signal connecting the tip of the jacks at the photo resistor ends. The second one (shown in the video) mutes the sound completely (this is the effect that I'm looking for), while the beavis audio one seems to be just lowering the volume. I'm still not sure about the cause. But the problem with the approach that I'm using is that It's not recommended to open the circuit and I don't see a good way to pan the signal between channels or chose the amount of signal to be stuttered in mono. Does anyone have an idea about what I'm doing wrong?

Alternative A: ground the signal (suggested in beavisaudio)
-in jack tip -> out jack tip
-in jack tip -> stutter -> ground

(doesn't mute completely the sound)


Alternative B:
in jack tip -> stutter -> out jack tip

(completely mutes the sound: the effect that I want)

Regards!
Beto

[beto]

you could also use a cmos inverter to flip the signal on the opposing channel

would 4066 do the job or is there a simple alternative?
Thanks!

[beto]

Definitely CMOS tristate is the way to go. The problem was that LED + PhotoResistor approach is good for cutting the signal (not recommended) but not for grounding. So I think that the best approach is to connect the IC 555 output to a IC 4066. That solves all the problems and let you a lot of options for stereo outputs or indicator leds.
Thanks for the help and the usefull ideas
Beto

[beto]

you could also use a cmos inverter to flip the signal on the opposing channel

4066 is doing a lot of "CMOS switching noise", I will have to try with the 4051 mux/demux. I have read about switching noise but I think that don't have the knowledge yet to tackle with this issue. Any easy workarround for this?