More Experiments - Envelope Generators this time...
Deathlehem - experience the joy
rmiller at pangea.ca
Fri Nov 24 01:46:45 CET 1995
>From: Don Tillman <don at till.com>
>Subject: Re: More Experiments - Envelope Generators this time...
>> Date: Wed, 22 Nov 1995 11:20:40 -0700 (PDT)
>> From: gstopp at fibermux.com
>> So I was thinking that the best kind of switch would be one with zero
>> on-resistance, which of course is a relay. Now don't get all huffy on me
>> and say that relays are "old technology" or "crummy"; the modern > >
>> micropower DIP relay has some pretty darn good characteristics, like >>
>> logic-level switching and the ultimate in signal-passing characteristics
>> (it's like a
>> damn wire!). It wouldn't be appropriate to use one to reset the cap in a
>> VCO, but for slow-speed work (like keyboard keypresses) it is ideal. In
>> fact the Moog 951 Modular Keyboard uses a DIP relay as the sample/hold
>> switch for the keyboard CV.
>Jeeze man, why not an automobile starter solenoid?
Hahahahaha! Ohhh. Sorry. :) HAhahaha. Sorry but that was funny. :)
>Seriously; there's something very wrong here. Before you reach for
>that relay, stop and think for a moment exactly how low a resistance
>you really need.
>Those readily-available-dirt-cheap CMOS switches (4016 et al) have a
>resistance of, from memory, something like 500 ohms or thereabouts.
>As you said above, your maximum readily-available pot reistance value
>is 1 Mohm. That gives you a 2000-to-1 ratio for your slope. If your
>capacitance is about 20uF or so, that give you a range of 10 mSec to
>20 Seconds, which is pretty much exactly what you want, right?
I've built the EN 4016 based ADSR with 2M5 pots and 2.2uf caps as well as
the EN AD/AR ADSR (which I modified to be an AADSR) with 1M pots and 3.3uf
caps and noticed a slight sluggishness in both of them. This is why I'm
attracted to the relay idea myself.
Also, because I'm a transistor idiot, admittedly. (I learned opamps first,
and am still groking transistors).
My only concern, as an astute reader (who's name escapes me) pointed out, is
the fiery blast of electrons squirting out of a fully charged cap, through
that poor little 1 amp sized (assumedly) relay, to ground.
I'll have to check my Potter & Brumfield Technical databook tomorrow at work
(them, whose relay I would use, as we're a supplier for them) and see what I
Ultimately for me, if this idea can be used for making EGs more simply, it
could finally lead me to a good solution for the 8 step EG that I've been
wanting to build for a long time.
Take care all,
Ric Miller - founder of Deathlehem
Wave files available for ARF, Bernie and
Deathlehem are available
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