What is an ASM-1?
gstopp at fibermux.com
gstopp at fibermux.com
Fri Oct 18 18:08:21 CEST 1996
Hi DIY list,
In order to answer the periodic questions that come up about the
ASM-1, here's a snippet of e-mail from earlier this year:
************* Beginning of e-mail snippet **************************
Hi DIY List,
I've had a circuit board made. I just got the prototype back and
started to stuff the parts, and so far it looks like it's a cool
thing.
It has two saw/pulse VCO's, a multi-mode VCF, two ADSR's, two VCA's,
an LFO, and a White/Pink/Random Noise Source. It's basically similar
to an Oberheim SEM, except for the noise source and extra VCA. All
circuit sections are discrete - in other words, no hard-to-find custom
synthesizer chips! The circuits are based on the Electronotes modules
that I've experimented with lately.
Here's a brief description of each module:
VCO - based on the Electronotes sawtooth design, with a CA3140
integrator with FET reset, controlled by an LM311 comparator. The NPN
exponential converter can be an Analog Devices MAT-02 matched pair, or
a pair of hand-matched 2N3904's. A 1K tempco resistor can be used for
best stability but is optional. There are 6 exponential CV inputs, 2
linear FM inputs, 2 pulse width inputs, a sync input, a sawtooth
output (-5v to +5v), and a pulse output (-5v to +5v).
VCF - based on the Electronotes state-variable design. The exponential
converter is based on one 2N3904 and two 2N3906's. The integrators are
CA3080's buffered by CA3140's. There are 4 exponential CV inputs, one
inverted exponential CV input, 4 audio inputs, and one buffered output
each for Lowpass, Bandpass, Highpass, and Notch.
VCA - based on the Electronotes 3080 linear design. There are 3 CV
inputs, one (+) signal input, one (-) signal input, and one output.
ADSR - my own design from a couple months ago, using an LM358 for the
input comparators, a CD4002 for the attack flip-flop, a CD4053 analog
switch, and a TL082.
Noise Source - based on an Electronotes design. It uses a
reversed-biased NPN transistor junction followed by a series of op-amp
filters.
LFO - typical tri-square manually-controlled design.
PCB dimensions are 4.8" by 11". Power required is +/- 15 volts.
I wanted to try out my CAD package and local circuit board vendors, so
for the first project I decided to make something useful instead of
just a single module. I would like to offer this circuit board to
other people on the mail lists. I want to make a run of circuit boards
and sell them, and I need feedback to get some commitments on just how
big an order I should place. The more I order the cheaper they'll be.
Note: I do not have any unrealistic ideas on making a huge profit
here. This is my hobby and my only monetary goal would be to recoup
the film and PCB setup costs (a few hundred dollars) plus some time
and energy spare change. I expect that I'll be able to sell the bare
boards for around $60 each.
Any interest?
- Gene
gstopp at fibermux.com
*************************** End of e-mail snippet ********************
You can e-mail me for details.
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