stylo-tone layout, 555 stylus organ

[choklitlove]

 here's what i've been working on:


it is based on this circuit:
http://i49.photobucket.com/albums/f295/choklitlove/circuit.gif

which is in this book:
http://avensonaudio.com/tech/MiniNoteBooks/MiniNotebook%20555%20Circuits.pdf


my question is: would my idea/layout work?  if it doesn't make sense, just ask.  also, what would be the + and - for the speaker?  i thought it would be the positive connected to pin 3, but the suggestion for the volume pot (on the schematic) threw me off being on the other side.

thanks! 

[tiges_ tendres]

DAMN!  I was just bread boarding a sylophone based on a 555 from the forest mims mini book!

great minds think a like!

I cant tell you the nights I have trawled the internet trying to find a stylophone schematic.  I was going to post here, as stylophones were big in germany, australia and britain, and I thought one of those good people might point me in the right direction.  Oh well!

[choklitlove]

do you have a stylophone?

i do, and i identified all but a few of the parts.  next is breadboarding forever to see what works.

i too, searched tirelessly for a schematic.  i found the patent here: http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB1160839&F=0&QPN=GB1160839
it has somewhat of a schematic, but no part values.

i'll let you know if i ever make any progress on the actual stylo.

[Paul Perry (Frostwave)]

It doesn't matter at all which way the speaker connects. The + and - on speakers is just so in a stereo (or in a multi speaker box) they are phased the same way & don't cancel.
As forthe Mims stylo..... that's nothing like the original stylo (which used a unijunction transistor based relaxation oscillator with a different resistor for each key).
An enormous advantage of the Mims one, is that you can put a pot for one of the resistors to give 'experimental' tunings or a whammy effect.
the disadvantage, is trying to get caps accurate enough.. if you are serious about note accuracy, plan to put TWO caps on each key

[choklitlove]

It doesn't matter at all which way the speaker connects. The + and - on speakers is just so in a stereo (or in a multi speaker box) they are phased the same way & don't cancel.
As forthe Mims stylo..... that's nothing like the original stylo (which used a unijunction transistor based relaxation oscillator with a different resistor for each key).
An enormous advantage of the Mims one, is that you can put a pot for one of the resistors to give 'experimental' tunings or a whammy effect.
the disadvantage, is trying to get caps accurate enough.. if you are serious about note accuracy, plan to put TWO caps on each key

i know the huge differences between the two.  i am not concerned with note accuracy, but i know the notes that are closest to the frequencies that each capacitor will create.  this is just going to be a noisemaker project inspired by the original stylo.

[KerryF]

Cool.  So... what does this do?  And why do you have all that extra on the copper traces?

[Meanderthal]

 See the pad marked stylus? Ya hook up a test probe and touch it to those 'extra' square thingies. Kind of a flintstones keyboard. Should sound buzzy.

[KerryF]

Oh sweet!  So is the stylus thing just a wire that you probe with?

[Meanderthal]

 Yup.

[tiges_ tendres]

this is the closest thing I found on a german website to a schematic.

I keep meaning to buy a stylophone, but I never get round to it.  I want to build one.

[tiges_ tendres]

Oh sweet!  So is the stylus thing just a wire that you probe with?

It's actually a pen.  when you touch the metal pad with the metal tip of the pen, you make a connection that makes a note!

[tiges_ tendres]

I'm having to run my noise maker through a vibrato to get something the resembles a stlyophone.  Not even close.

Rolf Harris didnt have these problems!

[John Lyons]

COol stuff!

Where can I find the schematic for the Mims unit?

[Paul Perry (Frostwave)]

COol stuff!

Where can I find the schematic for the Mims unit?

The layout given in the first post, should be enough to draw a schematic.
Note that pin 1 of the 555 is the upper right pin in the diagram.

[choklitlove]

COol stuff!

Where can I find the schematic for the Mims unit?

it's in the first post.  there's a link.

[Meanderthal]

 Oh, THAT schematic... from the old rat shack 555 notebook... I forgot 'bout that...

[Alex C]

I've been thinking of something like this for the past few days- I didn't know this was how a stylophone worked.

I've been messing with simple 555 oscillator circuits, as well as the Atari Punk Console.  One was a metronome with a pot for tempo adjustment.  I also added a switch that subbed in different caps for faster oscillation, and it turned into a little noisemaker with the pot adjusting the frequency of the tone, over several octaves. 

In this case, the C value was constant, and the R was varied to achieve the desired pitch.  Would it be possible to do something like this with the stylophone?  For example, multiple trimpots could be used for the differing R values, to allow for precise presets of the frequencies, and the probe would complete the circuit through a single R value at a time, rather than switching in a different cap.  If feasible, this seems easier than subbing combinations of caps until the desired frequency is achieved, and allows for easy adjustment in the future (for example, if tomorrow you decide you'd like everything shifted two octaves up, fine- just twiddle the trimpots, and you're set).

I can't get it straight in my head right now how the connections and switching would be done, but I'll think about tomorrow.  I'm also thinking about more switches for different cap cominbinations, like the "whammy"-type octave switch on the HOG.   I'll see what happens.

[John Lyons]

Oh, ok, I thought that paul said that the one here was nothing like the Mims circuit...
My fault...

John

[Meanderthal]

 I had thought about building something like this using those little el-cheapo momentary switches... I had to kick myself for not recognizing it from the layout. I never thought about the stylus method... just never occured to me.

[lovekraft0]

Let's not forget Mr.Escobedo's Synthstick, basically a stylophone with a clever homebrew ribbon controller. It's simple (a single CMOS chip), low current/voltage and easy, and avoids the problem with tuning caps by using a variable resistance to set the pitch. Replacie the ribbon controller with a set of trimmers and pads, and, voila, instant stylophone-like device!