stylophone mod

[>>>marjan<<<]

Hi,

> 
> So.
> I bought a stylophone. 

Ahhh...  I have one of those. It's black basic model
(no LDR, one pen, power and vibrato switches only, freq tune
on the back)


> NB: Between all keyfields and the pen, the 9 volt batterypower is here. So
> the actual keyingcircuit is not a standard resistorbank. Or am I wrong?
> 

It IS the standard resistor string. The whole cct is very simple (thou 
uses some not very familiar topology).All analog. 3 or 4 transistors.

And between the "keys" you'll have to find only blank PCB material,
all the pads are Cu, mine were scratched and oxidized, so I used some
rubbing alcohol to clean it, and then scrubbed with some Ajax :)
and final touch was water sand paper #1000 grade (I don't know if it's
standard) the you use for clear plastic canopies of plastic aircrafts,
esp on Airfix blurry ones :)

> As it is far from a synthesizer, I feel like needing a few modifications.
> 
> 0. The frequency down with 1 or even 2 okatves. It will probably mean
> cutting out a R and solder a pot in somewhere.

My idea was to add suboctaves. No schematic, but idea is to take the
output of oscillator
(square I think), via some tranny buffer, to 4013 classic dividers 
and mix them via two 3position switches (off/half/full volume) that's
something I saw on some modded tb303 (Kevin Synthfool?).
Look for the SH101 schematic of subdivider, or at TomG.

Droping down the main ocs oct down - well just add some cap in
parallel to exisiting one...

Also I want to add frontpanel (like there's enough room :) tune,
vibrato speed and level.
 
> 
> 1. Portamento.

If I remember correctly - no. It's sorta multivib osc. 

I haven't thought about it thou, but I have traced stylophone cct, so
I'll
redraw it nicely so people could see it.
The only thing puzzles me are the transistors
they're unmarked and I just don't feel desoldering them to check them

> 2. a frequency wheel/knob.


There's one beneath the box.

> 
> 3. Dirt
> So, back in the tough the electronics topic!
> I definitely need some dirt in this machine. Toughing the keys lightly does
> sound dirty already, as it's switching on and off all the time (noise
> modulation).
> Any ideas?
> 

Switches used are pretty lame, so they easily break, esp for all this
time.
Try to find similar ones and replace them (also connect in parallel
poles
on each switch, every one use just one pole, connect to that pole second
one it should help somewhat)

I got nice results with this setup
stylophone->SVF->ibanez dm1000 (heavy flanging with resonance)->analog
delay ad9


Cheers,


marjan