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

[Karl Ekdahl]

Hi Jaroslav, i've tried changing the 4.7k to Reset
since it seems the VCC feed was to low, but without
any luck. The 555's i tried are CA555CE from Harris
and RCA, and also a NE555N from ST. Earlier i also
tried NE556A from ST. I can't verify wheter this
circuit does actually run from a +-15 since i don't
have anything but a +-9V supply here (i've moved
recently).

Thanks
Karl


--- Jaroslav Luke¹ <lsh.synth at seznam.cz> skrev:

> > 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.
> 
> 
> 
> 
>