These are my build notes for the Nonlinear Circuits Mobius Pill.
The MP is a chaos - noise module in Eurorack format.
So if you like chaotic noise this is for you.
The BOM looks pretty standard with no rare or hard to find parts.
You will need two 4046 ICs.
These are your PLLs (Phase Locked Loops).
(These PLLs create the chaos.)
There are also two Op-amps. These are standard 072s.
In addition to the two PLLs the circuit also has two vactrol based low pass filters
These filters are in the Buchla style... I think they are 292 inspired gate/filter combos.
The vactrols are all DIY (black box design) using LEDs and light dependent resistors.
The PLLs have a single combined voltage control input.
Each filter has it's own voltage control input.
Thanks to Andrew for supplying this diagram.
It explains what's happening in this circuit.
There are two TL072 op-amps, two VCOs, two filters , and two PLLs
The phase detectors feed into the LPFs and theirs outputs are fed into the non-inverting inputs of one and the inverting input of the other.
The outptuts of each control VCOs.
There are 4 inputs & 4 outputs.
Inputs:
Input signal, Freq CV, LPG1 CV and LPG2 CV.
Outputs
Two of the outputs are from the LPGs and two are from the PLL VCO
Some pics of the virgin PCBs.
LEDs go here. These LEDs are part of the vactrols.
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The 4046 IC -- it contains a VCO, two phase comparators & a zener diode.
The zener diode acts as a voltage regulator, setting the voltage at
5.1V. across it, for voltage input into pin 4. This is the voltage
that controls the number of oscillations for the output digital signal
of the chip
The oscillator will produce a digital square waveform .
Analog input to the VCO is at pin 9.
Digital output of a square wave is at pin 4.
This is fed into an op-amp and becomes the VCO 1 & 2 outputs.
PC (Phase comparator) 1 out (pin 2) becomes the LPG output.
Hopefully, this will help you trouble shoot, should you run into any probs.
These are mainly used for pitch bend (PITCH)
and vibrato (MOD).
The Pitch wheel is on the left. It is a spring-loaded wheel that snaps
back to its center or neutral position when released.
The Mod wheel is on the right. It is not spring loaded and must be manually
returned to its off position.
It is normally used for vibrato.
Of course, you don't have to use these two wheels as described above. Eg you can make both pitch bend , both vibrato, swap them, neither, etc.
You can assign these wheels
to modulate any parameter that is designated as a mod destination.
You can even assign the wheels to perform multiple modulations at the same
time.
The pitch wheel is usually set up so that pushing it away from you bends played
notes up in pitch and pulling bends them down. This setting can be reversed.
It can also have a different type of
modulation on either side of the center stop.
Programming the Wheels
To make changes to either wheel, press the PITCH
(“Pitch Wheel”) ASSIGN
or the MOD (“Mod Wheel”)
ASSIGN button.
The parameters for that wheel will
be displayed
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CHORDS
The CHORD button allows you to play a chord with a single key.
To define a chord,
hold down the CHORD button until the chord LED starts to blink.
Then, play the
notes of the chord and release the button.
After the chord is in memory, playing a single note on the keyboard will play the
chord relative to the note you played. To toggle chord mode on and off, simply press
the CHORD button.
Kitarō (喜多郎), born Masanori Takahashi (高橋 正則)
(February 4, 1953), is a Japanese musician noted for his electronic-instrumental music. He is really famous for using this instrument.
The music was composed mainly using a Minimoog, Minikorg 700, and Maxikorg DV800.
I'm so looking forward to this re-issue of a classic.
I've had my old miniKorg 700 since 2011 and today decided to re-explore it in preparation for
the re-issue coming out soon. My version doesn't have midi, or CV control. There isn't USB connectivity, a sequencer, memory, or even a second oscillator.
It was released in 1973, retailing for $500 USD. (I paid $500AUD for mine in 2011).
The 700 was Korg's first monosynth but was released under the UNIVOX brand in the USA.
It has 37 keys, a 2-speed phaser, and a variable pitch slide.
To put this in context, the early 1970's was an important period in the development of the synthesizer.
The ARP 2500 came out around 1970, as did the Moog MiniMoog & the Buchla 200 series.
1971 saw the ARP 2600, the EMS Synthi 100 & Synthi A.
1972 saw the Buchla Music Easel, the ARP Odyssey (Mark 1), the Moog Sonic Six, The EMS Synthi AKS & Synthi E.
1973 saw the Moog Satellite and modular 15/35/55.
The Korg company had been around since the 1960's. They mainly made drum machines.
As mentioned earlier, this was their first mass produced monosynth. They were probably trying to cash in on the craze for pre-patched performance instruments like the Minimoog and Odyssey.
It started Korg's journey to become one of the world's great synthesizer manufacturers.
The Korg700 was meant to sit on top of a larger keyboard (usually an organ). Thus most of the controls have been placed under the keyboard, not above as is usually the case.