[sdiy] 555 cv level?/Psuedo Random Generator

[dragon.servicing]

Hi Dan,
I couldn't get the second link to work....

to try to answer your questions ( I'm still trying to find my way around 
the 555 ic ! ).

1. it is possible that a higher supply voltage might not work as the 
output from the 555 might not link to the cmos ic's correctly. but I may 
be wrong ( it needs more thought ! ).

2 I think the cv into the 555 should start  at a certain fraction of the 
supply rail, maybe it is  2/3rds so this would be different for +5 and + 
12 volt supplies....
but as to what change in frequency you get for a certain change in 
voltage, I'm not sure.
hope you can sort things out.
regards Peter




Dan Snazelle wrote:
> 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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