[sdiy] Possible New Waveform Generator Circuits

[Steven J]

I have previously sent a post that was similar to this one
to the synth-diy list, but it contained a question without
proposing a specific solution. I learned later that no one
knew the solution because it had never been made before. I
sent my proposed schematic solution to the analog heaven
list, but the people there did not have the electrical
engineering expertise to determine whether the solution was
correct or not, and furthermore there were several
psychopaths on the list that strongly libeled me because I
did not fulfill nitpicking requests, due to the extremely
ineffective criminal justice system. Harry Bissell then
strongly suggested that I send my proposed schematic
solution to this list, where the list members can
understand it and would want to know it. That post is as
follows, though it has been slightly modified:


I have looked at various websites that describe the
waveforms that are produced by synthesizers. For the most
part I could only find sine waves, square waves, triangle
waves, sawtooth waves, and waves that combine those
waveform types. Of those types, only the sine wave is
smooth, whereas all of the other waveforms have sharp
angles. There is a way to drastically alter a waveform in a
very simple fashion in such a way that the waveform
remains nearly as smooth as a sine wave. That method of
alteration is to successively increase, or successively
decrease, the size of a wave from the beginning of the
waveform to it's end, thus resulting in an outward
spiraling waveform or an inward spiraling waveform,
respectively. These modifications are made to each of the 2
arcs of the sine wave cycle. I have asked about such
waveforms on multiple mailing lists, and no one is
familiar with them. I am surprised that such waveforms are
not already common, considering how basic they are.

I have designed circuits that theoretically create such
waveforms, but they may not work. Specifically, I have
designed a modifiable 2-way oscillator circuit to which
waveform-modifying components can be added, and I have
designed the modifying component that allows the creation
of spiral waves, which may be called 'the spiral waveform
modifying component', or abbreviated as 'sWMC'. The
schematics of those circuits are below, written with text
symbols. The sWMC uses a potentiometer to regulate, in an
analog fashion, the curve of the spiraling arc. This allows
the human operator to use a knob to change the spiral
vector at will. The sWMC in the schematic below only
creates an inward spiraling arc, but it is a start. The
schematics below have explanations of their functions.

These circuits are untested, but they are likely to work.
Being as I do not know if these circuits will successfully
generate spiral waves, as I do not own an oscilloscope, I
request that someone who thoroughly understands analog
electronics analyze these circuits, and reply stating if
they will generate spiral waves or not, and if not, then
additionally describe the circuits that will successfully
do so. I am also posting these schematics because other
people may want to know of them. The schematics below,
complete with their descriptions, may be copied and
distributed and/or displayed freely by others, but false
credit may not be given for them.


For the following schematics, periods represent spaces, and
the following legend applies:

'O' = wires that do not cross,

'\_/'
.|_| = speaker,

'-/+' = battery,

'P' (uppercase) = potentiometer,

'X' = field effect transistor (FET),

'||' or '=' = capacitor,

'R' = resistor,

'p' (lowercase) after a resistor or capacitor = indicates
that it is the primary resistor or capacitor of the
oscillator,

'<', '>', '^', or 'v' = diode, with the point indicating
the flow of positive charge,

'>|', '|<', '_v_', or '__' = transistor, with the flat line
........................^
representing the base


...............\_/
....___________|_|__Rp_____________
.../.......|................|......\
...v.......|................v......|
...|.......|................|......|
...|.......|................|......|
...|.......|................|......|
...|.......|................|......|
...|.......|................|......|
...|.......>|_____v___......|......|
...|.......|.......\...\....|......|
...|.......^........R...|...|......^
...\__-/+__|____||p_|___|___|_____/

ohms of Rp x farads of ||p = 0.01 - 0.001

MODIFIABLE 2-WAY OSCILLATOR TEMPLATE
operation:
The primary capacitor is charged through the primary
resistor, the speaker, and the outside pathways. Diodes
prevent the inside pathways from carrying the charging
current. The last diode that the current passes through
traps the charge in and around the capacitor. When the
capacitor is charged, the current is diverted through the
nearby resistor, which in turn activates a transistor,
which creates a resistance-free pathway that diverts the
trapped charge. The charge falls onto another transistor,
which activates the reverse pathway which drains the stored
charge. The reverse current passing through the speaker
and primary resistor prevent the forward current from
flowing during that time. When the capacitor is drained,
the transistor switches off, the reverse current switches
off, and the process repeats.

possible specific values:
battery = 1.5 volts, Rp = 100, ||p = 10 microfarads,
other R = 10K
This circuit as it exists might generate rough square-like
waves, as opposed to smooth sine-like waves, which are the
goal, the reason being that it contains no specific
mechanism to control the degree of current that flows
through the speaker. It may be possible to correct that by
adding a transistor to both the charging path and the
discharging path, such that each is controlled by a 
resistor from the same pathway, thus amplifying
the time that it takes for the current to reach full, and
the time that it takes for the current to cease.


.............................
............................|
....|......................_X
....|...................../.|
....X_____________...____X..|
....|.............\./....|..|
...................|.....|...
...................P.........
...................|.........

SPIRAL WAVEFORM MODIFYING COMPONENT
This is a schematic of a circuit component, rather than a
complete circuit. Because of that, there are wires that
terminate without completing a circuit, as such wires tie
into the complete circuit.

operation:
The potentiometer controls the voltage that flows through
it. On the pathway on the left, a high voltage activates
the FET. On the pathway on the right, a high voltage
activates an FET, which in turn stops a current that is
activating a secondary FET, thus it deactivates the
secondary FET.


...............\_/
....___________|_|__Rp___________________
.../.......|......................|......\
...v.......|......................v......|
...|.......|......................|......|
...|.......|...................___X......|
...|.......|................../...|......|
...X_______O____________...._X....|......|
...|.......|.............\./.|....|......|
...|.......>|_____v___....|..|....|......|
...|.......|.......\...\..P..|....|......|
...|.......^........R...|.|..|....|......^
...\__-/+__|____||p_|___|_|__|____|_____/

SPIRAL WAVEFORM GENERATOR OSCILLATOR
operation:
This operation description assumes that the potentiometer
is set such that it allows current to flow through. In the
pathway on the left, as the charge of the capacitor
increases, the voltage on the FET increases, thus
decreasing the flow of forward current. In the pathway on
the right, as the charge of the capacitor increase, the
voltage on the primary FET increases. There is a second
pathway, which leads from the area of the charged capacitor
to a secondary FET, which, when activated, shuts off the
reverse current. The secondary FET is much more sensitive
than the primary FET of the right-side pathway. As the
voltage on the primary FET decreases, the voltage on the
secondary FET increases, which in turn decreases the flow
of the reverse current.
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