WSG Mods for a sequencer thingy
So the purpose of this submission is to explore Ray Wilsons Weird Sound Generator a bit and figure a way to put in a sequencer of sorts.
There was a question on the electro-music board if anybody had been able to connect the WSG to say a step sequencer. This could be done, but not exactly directly. Most modular synth circuits operate on a Control voltage of 1 volt/decade - octave or whatever your controlling. This is usually a 10 volt range. The WSG operates on 9 volts (although you could do a wide swing of that if you wanted), so a CV might even get you a little higher than you want. Im sure you could just tap in something like the Baby 10 Sequencer and it would tweak the circuit just fine. Still, the spirit of the WSG is a “your first synth” kinda thing and really is a fun platform if you will for smaller scale experiments.
The experiment I did was just to have a simple 4022 running as a simple 8 step sequencer. I will not have 8 knobs…maybe 3-4 at most or some hard-wired (as hardwired as a breadboard gets).
First, lets look at what makes the WSG tick and see what we can then tweak. The basic building block of the WSG is the schmitt trigger inverting gate.
So, its a simple invertor, oscillating frequency is based on the RC constant AND the Vcc voltage.
This is because the frequency is based of the threshold voltages, which are directly correlated to the source voltage.
Here is a audio sample of the circuit with me changing the values of the resistor (its a pot).
Exploring the “Wacky” component
The Wacky component of the WSG is an oscillator gated by a diode. When the “Wackiness” is turned on, “Wacky” generator (a squarewave generator) applies a voltage to a diode that in the RC loop of the main oscillator. For simplicity I removed the transitor….that will be explained later.
As is explained in the diagram. When the voltage is high on the diode, the circuit acts normally. When the voltage is low, the current grounds out and capacitor never really charges.
Diagrams here explain it best. Pretty neat stuff.
Here is an example of the gating effect taken to the extreme. Three gates in Series to emulate a phone ringing.
An example is here.
Sorry that it takes a bit to get to the part…but at at 17 seconds into the sample, the wacky is turned on. The main oscillator and the wacky oscillator both have a .022 uf capacitor which makes both oscillators ring at the same frequencyish. When the first one gates the second, it kinda has a ring modulation sound to it. At about 28 seconds in to the sample, the zany is turned on.
Zany experiments.
The Zany component is basically a switching transistor in the loop of the main oscillator.
When the voltage is high on Vin, the transistor shorts across R2 and the effective resistance in the loop is R1.
When the voltage is low, the transistor is off and the effective resistance is R1+R2.
When the voltage is somewhere in between, the current is partially drawn and a frequency somewhere inbetween is found.
The Zany oscillator is acting as an LFO that is sent through a voltage divider. That is the “Zaniness” amount. With a very low voltage swing, the transistor is not switched on. For a small range, the frequency will change until you reach the voltage that turns on the transistor. Increasing the Zany after will have no further effect.
Some sound examples are here
Example 1 - The Zany frequency is changed only.
Example 2 - The Zany amount is changed. Note that the frequency of just one of the tones changes.
4022
http://www.datasheetcatalog.com/datasheets_pdf/M/C/1/4/MC14022.shtml
Here is a good link pointing to another sequencer.
links
http://www.experimentalistsanonymous.com/board/viewtopic.php?t=233
http://www.talkingelectronics.com/FreeProjects/555/555-P3.html