[sdiy] 555-based ADSR that refuses to work with 9v

[Jaroslav Lukeš]

> diy at dropmix.xs4all.nl] On Behalf Of Karl Ekdahl
> Hi all, i'm currently trying my luck adopting another
> René Schmitz design to 9v. The 555-based adsr2;
> http://www.uni-bonn.de/~uzs159/adsr2.png

Did you try to change resistor values?

> I don't get the ADSR to work, it seems like the
> reset-pin doesn't like the non-reset VCC feed it gets

Which 555 do you use? Some manufacturers make 555 with some different
functions than original!

> from the transistors. It resets fine with the circuit
> given but it can't be set again unless i manually move
> the wire from Reset to VCC. Of course, i've measured
> the collector tied to Reset, and it is approx. 8.8V
> which should be more than fine as i understand it.
> 
> I just thought there might be some "magic" as with the
> noise source that i had to tie to -9 instead of GND.
> Btw, could someone explain that a little closer? JH
> mentioned the reverse breakdown voltage or "zener"
> voltage, BE, but that is stated to be 6V for a
> BC547...  ??

No it does not have nothing with "zener" voltage, it is more like avalanche
principle.

You could select transistors to get noise from <9V voltage, I was make
little portable battery powered synth for my childs, that runs noise from
cca 7V (under this voltage noise generator does not work). I use some >20yrs
old czech Si transistor.

Regards, JL.