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

[René Schmitz]

Hi Karl and all,

Karl Ekdahl wrote:
> Maybe i'm really confused, i've rewired the circuit 3
> times on a breadboard and my conclusion is this: the
> circuit triggers fine applying a +9v trig at the
> junction of the 10n and 10k, though while trying to
> trig it from the "actual" trigger it works spordically
> every now and then. As i understand it, after
> fiddeling a little, the 10n cap gets a charge from the
> trig that it doesn't allways gets rid of before the
> next trig thus not retriggering. 

Try a diode at the base of the third transistor, configured like the 
protection diode at the input. Maybe there is really an action from the 
reverse breakdown, helping to get rid of the charge. Which wouldn't be 
effective with a lower operating voltage.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159