[sdiy] 555 cv level?/Psuedo Random Generator Circuit..wow/questions

[Tim Stinchcombe]

Hi Dan,
	Not had the time to fully digest the circuit as yet, but when I was
specifying a 555 for a circuit about 6 months ago, I seem to recall that not
all 555s/556s are alike, particularly the CMOS flavours, things like what
current it could source/sink etc. Thus question no. 1 is: what is the make
and exact type you are using?

Tim
__________________________________________________________
Tim Stinchcombe 

Cheltenham, Glos, UK
email: tim102 at tstinchcombe.freeserve.co.uk


> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Dan Snazelle
> Sent: 09 June 2008 13:24
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] 555 cv level?/Psuedo Random Generator 
> Circuit..wow/questions
> 
> 
> 
> I built this last night and i have some questions:
> 
> http://www.media.mit.edu/physics/pedagogy/fab/electronics/Fab-
assignment-ckt-10-00.pdf


and here is the text:
http://www.media.mit.edu/physics/pedagogy/fab/electronics/assignment.htm


QUESTIONS:

1.I had hoped i could run it off of 12volts but that didnt seem to
work...anyone know why? resistor values?

2. WHAT IS THE VOLTAGE RANGE OF CV IN ON the 555/556555? (pin 5) He mentions
that the single supply opamp (would a 324 work?) is biasing the voltage for
the 555's cv Input. if i knew more about what the range is, i might be able
to get this working better.

3. MODIFICATIONS: any ideas? I am looking for ways to change the tempo, or
mainly, to add CV control of more parameters. I WOULD LOVE TO BE ABLE TO
FIND A WAY TO ADD AN EXTERNAL VCO IN PLACE OF THE 555. i did a quick
experiment where i hooked my Ray wilson VCO(powered off of +/- 15v) into the
CV in/audio Out loop and took the 1st half of the 556 out of the circuit. IT
DIDNT WORK. is it because the CV voltage this circuit is producing is all
wrong? or is it because the voltage of the Ray WILSOn VCO is all wrong?

I figured if i used the square on the ray wilson VCO as the sound source,
and put the signal that was meant to be the CV in on the 555 into the 1/v
oct in on the ray wilson VCO, it would work in a similar fashion. IT DID
work as a sound source. but not as a sound source being modulated by the CV
from this circuit.


any opinions, help, observations, or similar circuits/theory would be highly
appreciated. this circuit is EXACTLY the kind of stuff i am looking to
build.


thanks


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