[sdiy] Kraakdoos

[Metrophage]

--- Pete <23isgood at gmail.com> wrote:
> I have been working on a Kraakdoos myself, and I also plan on
> building it into a Pac-Tec case! 

Neat!

> My prob with the Kraakdoos is that it is not stable at all, and I 
> know the thing is not stable already but I mean that there is 
> allot of noise and it picks up radio signals, and thats really
anoying.
> I was thinking that it needs power decoupling. What do you guys
think? 

The Kraakdoos is unstable by design, it starts stable (silent), but
when contact occurs, it gets chaotic. It can go from silence to
complete noise, but usually bounces around in between.
As for external noise, same here. Actually, it depends which contacts I
touch, there are a few combinations which seem to act like antennas.
I'd recommend ordinary RF shielding, metal or metal-lined case, screen
covered wires inside. I have my doubts though, as there is usually no
radio reception until I touch it a certain way. I'll try wearing my
foil suit >;]P


> I built mine according to the schematic on this site,
> http://www.eam.se/kraakdoos/

Me too! I am going to try to elaborate on this design sometime later.
Definately using breadboard for the next one.

> Sometimes mine sounds like the mp3 samples on that site but the noise
> and radio interference really ruin the sound. I think that im getting
> feedback or unwanted oscillations, im not sure im still learning.
> Does yours sound like this? 

Basically, yes. I don't know what are unwanted oscillations, in this
sort of context! My first tries sounded like blasts of squall, not very
interesting. After a while, I was able to finesse the contacts into
making mostly bleep kinds of sounds. Looking at the schematic, one can
see that contacts are at certain points of the circuit. Remembering
what parts you are interacting with when a given sound event occurs,
one can learn how to induce the desired behaviors. (sounds like
behaviorists operant conditioning, but is far sexier). 

> Also I would add the transformer right where you place the speaker 
> and connect a 1/4" jack to that and see if that works, im not sure im

> guessing. Maybe even add a switch so you can go from the built in 
> speaker to the jack. I would like to be able to plug some headphones 
> into the thing so you could play with it while on the buss or Bart
(SF subway).

I will try a few transformer arrangements. Any 1/4" output jack will
work, but the signals can get a bit brutal at times. I'd be very
cautious about connecting it to anything - start volume from zero, and
increase. As for headphones, I seriously advise against, until you know
that you have a handle on the output. My Kraakdoos wants to blow out
ears from across the room, I am not even going to think about
headphones yet.


>  On another note I went to see the Moog documentary in SF recently.
> Before the film they where showing these homemade films from the 60's
> and there was this guy playing a Kraakdoos in the film! It was pretty
> big and he was playing it by putting his fingers right on the metal
> cans of the transistors! It also sounded very good and stable. It had
> all kinds of knobs on it. I wish I could find the details on that
> one.

I can hardly wait to see the Moog documentary! I barely missed the only
screening which I would have been able to get to. Guess I'll hold out
for the DVD. I've got to wonder about what other films they played!
Interacting with circuitry can be quite fun. For more STEIM antics,
their website is quite interesting. Recently, the MIT HyperInstruments
people have been working on Squeezables and BeatBugs, which are also
hands-on, zero-knowledge music toys for children, non-experts, and
others wanting fun audio.
CJ


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