[sdiy] asm-1/asm-2

[Gene Stopp]

Yes good idea (hi Magnus!)

What happened is that the LM358 input comparator is powered between ground
and V+ and negative voltages drive it batty. OK in pre-patched systems
(where the gate can be 0 --> V+) but bad in modular systems.

Best Regards,

- Gene


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Magnus Danielson
Sent: Wednesday, June 02, 2004 4:47 PM
To: BJB at dolby.com
Cc: Laxt57 at aol.com; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] asm-1/asm-2


From: "Brett, Bill" <BJB at dolby.com>
Subject: RE: [sdiy] asm-1/asm-2
Date: Wed, 2 Jun 2004 16:30:41 -0700
Message-ID: <5FCCC03CAF7C5C4C8E2F995E3D72E133040BABE9 at platinum.dolby.net>

> Since we are on the subject. . .
> 
> I just finished building up 4 ASM-1's.

Yeah! ;O)

> I believe I need to modify the trigger input of the ADSR to handle
> triggers that go below 0 volts (such as LFOs). I saved an email about
> this but. . . Can't seem to find it right now. I think it is just a
> diode shorting negative voltages to ground.
> 
> Any advise about this?

Yes.

Add a resistor in-between the Gate In and R1 and add a diode in parallel
with
R1, such that it becomes conducting when the input voltage is negative. R1
will
make sure that the inputs doesn't suffer from excessive capacitive feedback
and thus instability.

Cheers,
Magnus