[sdiy] Since it's 9/09, it's time for more 909 questions :)

[Colin Fraser]

> -----Original Message-----
> From: TooManySynths [mailto:p8051 at yahoo.com]
> Sent: 09 September 2001 21:44
> To: Colin Fraser; 'TooManySynths'; synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] Since it's 9/09, it's time for more 909
> questions :)
>
>
> One more question:
>
> I assume the accent pulse is a positive going pulse.
> But, does the attack accent get triggered off of the
> negative edge?  I ask this because the pulse is fed
> into the cathode of D5.

No.
The trigger pulse switches on Q1, Q1 conducts and pulls down the base of Q5
lower than it's emitter via D5 and R34. This switches Q5 on and allows the
accent cv to charge C12 for env2. This happens at the leading edge of the
trigger pulse.
The trigger pulse is inverted at the output of Q1. The inverted pulse is
inverted again by Q2 which charges C7 via D6.
The triggers at D5 and D6 are opposite senses. The non-inverted trigger at
D6 is inverted again by Q3 before it reaches the base of Q4 - which then
works in the same way as Q5 (with the difference that C7 and Q3 stretch the
pulse length, and give it a slight downward slope).
It takes a negative pulse relative to the emitters to switch on Q4 and Q5
(PNP).

Colin f

(Hope nobody's getting too bored with this yet...)