Saturday, 17 September 2022

Infinity Worm - 2022

 Some pics and videos from Infinity Worm, Canberra 2022 (Australia).
 


Elk Elektroniks had a display stall at the gig.
\

There were two stages ... This was the second stage .. mainly DJs
Called the Worm Stage
 

I have a new appreciation for Drum & Bass

\




The Main Stage was under a large tent.
 Called the Infinity Stage.

 

Low Flung



..


Laces ???


...

u-zig









Thursday, 15 September 2022

Ring Mod - nlc build notes

 These are some build notes for the Ring Mod module by Nonlinear circuits

 
This is a really easy module to build.
Great for a beginner.

Links
+ BOM


This module was developed from a paper by Tom Oberheim, presented at the 
Audio Engineering Society 1970 convention – A “Ring Modulator” 
Device for the Performing Musician.

The paper discusses the various types of ring modulators and states the transformers 
in the well-known diode ring modulator
 can be replaced with transistors. From pg.2 – The transistors serve as phase inverters 
for driving opposite sides of the ring. 
The differential amplifier amplifies the sum and difference frequencies while 
rejecting the signal and the carrier.


schottky


opamps
transistors

resistors
 caps - just 2















Such a simple circuit !!!


four LL 4148


100k pots
all linear

kobiconn style sockets







You're done


---------------------------------------------------------------------------------------------------
Click here to return to the NLC Build Index:
http://djjondent.blogspot.com.au/2015/03/non-linear-circuits-ncl-index.html 

Tuesday, 13 September 2022

Synton Fenix III - sequencer companion notes - 2

 This is part 2 of my companion notes for the fenix III sequencer.
 
 
Part 1 is here:

Note that the patch points are colour coded.
+ Inputs = Black
+ CV out = blue
+ Bus in/out = yellow
+ CV step input = grey
 
+ It is NOT OK to interconnect the blue outputs
+ It is OK to interconnect black inputs
+ It is OK to interconnect any number of yellow outputs
       These yellow outputs are binary (gates ... >7V or <1V)
       If one or more of the interconnected yellow sockets is HIGH, then all will be HIGH.
------------------------------------------------------------------------
Buffer Modules.
This module operates only for Logic signals ... eg those from the Yellow Bus outputs .
A Buffer is a special Logic gate. It's a non-inverting amplifier.
 
It is recommended to use a buffer module when connecting the yellow Bus to a normal gate source or an input (such as the clock input) which has internal patching.

A buffer will turn a non-buffered output (yellow jacks) into a buffered output.
When in doubt it doesn't hurt to use a buffer. Its a safety module.


--------------------------------------------------------

----------------------------
 
The Master clock module controls the speed of the sequencer
 
The Clock frequency can be set by the frequency knob
and modulated with an external voltage at the FM1 and
FM2 input or by external Midi
 
There are 5 clock outputs:
Clk out, 
Out x 4
Out/4
Out/16
Out/32
 
 
The Clock outputs are I understand to be same voltage range as Gates .. that is ... 0 to +8V
 (need to confirm with a multimeter) 

If you want to connect the Fénix with an instrument based on S-Trigger (Vintage Moog 
or Korg MS 20 etc), you need an S-Trigger converter. 
If you want to use an S-trigger to control the Fénix, you can connect the S-trigger to
 the (-) input of the comparator and the output of comparator
can be used as gate. You'll have to look for a correct setting with the control knob.

The CV out is the CV of the Frequency knob. 
You can use this as an additional control voltage. 

The R/S and Reset inputs need Gates to work.
Anything larger than +5V is high
Anything under +1V is low
 ------------------------------------------------------
 
The 3 main sequencers (C1/B1/A1) have some unique input controls:
 
To clock the sequencers using an external sequencer you'll need
a +5 gate (or larger).
A signal larger than 5 volts is considered
high, and a signal that lower than one volt, low. 
The gate and trigger outputs produce such a signal.






Triplet & Duplet









To be continued...

Friday, 9 September 2022

Thermin - Silicon Chip - build pics 2

Some build pics of the Silicon Chip Thermin.
 
This kit has been sitting in the bottom of a draw for about a decade and I only dug it out
after a friend asked for advice re building a thermin from the old Moog designs.
Though this kit isn't the same I thought I'd finally put it together to learn about thermins in general.
I think this old Jaycar kit is discontinued.
 
This looks like a very easy project that

is great for beginners.
All through hole components.
This is part 2 of my Thermin notes.
The first part of the build notes are here:
 
I'll discuss the circuit as I build the synth.
All Thermins start with this same basic circuit.
 
The basic circuit comprises 3 oscillators (reference, pitch & volume).
In this case they all operate at 455kHz.
Each oscillator is essentially identical.
They comprise a JEFT (junction field effect transistor) and a pre-wound IF (Intermediate Frequency) transformer. 
The JFETs are all 2N5485.
In this case the Reference oscillator = Q1 & T1 
The Pitch Osc = Q2 & T2
Vol Osc = Q3 & T3
 
The original Moog circuit used 2N 168 & 2N1086 transistors.
These are old GE  intermediate- and high-frequency transistors intended for use in radio receiver circuits.
I reckon these would be difficult to find today. 
 
 
T1,T2 & T3 are the pre-wound IF (Intermediate Frequency) transformers.
These are a modern substitute for the inductors used in the vintage circuits.
Looks like you can buy these on Aliexpress, etc
 

The Tone Oscillators (ref & pitch)

The Reference & Pitch Oscillators are mixed in IC1 (called the product detector) to produce a audible tone.
IC1 = MC1496
It's a balanced modulator/mixer.
You won't find this in the original Moog circuit where the two oscillators are mixed through two capacitors and rectified through a diode.
 
Its a pretty common chip .
Pretty old ... dates I think from the 1970s. Easy to find on Ebay.
The MC1496 is used here as a mixer.
The signal inputs are on pins 1 & 4 .
Carrier inputs are pins 8 & 10.
Outputs are pins 6 & 12.
 
The deeper I compare this circuit with the original Moog circuit, the more I realise
how components have changed over the last 70 years.
I guess this is to be expected.
I wonder if its practical finding all those old vintage parts if you wished to stay true
to the original schematics.

Anyway, back to the build.
The VR2 trimmer looks like an new addition to the original circuit..
I think this is a basic wave shaper ???
It varies the coupling between the pitch & reference oscillators that produces the final voicing
& adds some waveform distortion. 

The addition of this shaper circuit changes the final timbre.
It can now be varied from a pure sinewave (which is not characteristic of a Thermin) to  a much deeper sounding square/ramp tone, which I think has a lot more harmonic content.
 


The output from IC1 is fed into IC2.
IC2 is a LM358 op amp.
It acts like a low pass filter.
Again, you won't find this in the vintage Moog Thermin. 
That circuit has no ICs. Its all transistor based.
 

The output from the filter is applied to the power amp (IC3, LM386)
 and this drives the speaker.
 
IC 3 = LM 386
IC 2 = Lm 358
IC 1= MC 1496



The Volume Oscillator.
This is made up of  T3 & Q3
The secondary winding of T3  is connected to the base of Q4 (BC548)

The collector of Q4 is  attached to T4 (and its capacitor).
T4 is another IF coil.

To be continued ......

Thermin- part 3 build - completion

 PS: do let me know if there are any mistakes or omissions. Cheers Jono

Sunday, 4 September 2022

Synton Fenix III - sequencer companion notes - 1

 Some personal notes to help with the official manual

The Fenix III is a wonderful sequencer. 
One of the most flexible Ive every had the good pleasure to own.
It is totally modular.
 
You can view it as three main CV/Gate sequencers
with a 4th expander sequencer
The sequencers are a bit confusing at first.
I'll divide them into CV & Gate parts, then see how they work together.
 

The CV sequencers

From top the CV sequencers are labeled: C1, B1, A1 (blue knobs)
The 4th (expander) sequencer, named A2, has red knobs.
The sequencers produce CV voltages between 0 & 8 volt.
These are the CV outputs of the sequencers:


They can be clocked via the master clock, external MIDI or external CV.
By default, the master clock is connected to all 4, but can be overridden 
with a signal at the clock input or CV-step input

Sequencers B1, C1 and A1 are pretty standard 16 step.
Forward, ping-pong, random modes.
A2 is an expander of A1
The A1 expander can be 16 steps, 2 x 8 steps, or in Inverse Mute mode.
 

The Gate sequencers

 

There are 4 of these: C4, B3, A4 & A3
It is important to understand the difference between gate and clock signals
A gate is a continuous high signal.
A clock has a high & low state for every step.
The clock can be standard (50% high / 50% low) or variable (called a PW clock) .
The PW (pulse width) clock can be changed ... eg (10% high/90%low or 30% high / 70% low , etc  etc).
We can even apply a CV to modulate this pulse width.
 --------------------------------------
C4-C1
The C4 Gate sequencer is linked to the C1 CV sequencer
 

 The C4 gate sequencer uses 3 position toggle switches (as do all the other gate sequencers).
In the manual, C4 is called Gate expander 1 (page 17).
The extreme left toggle with the yellow cap switches between Gate/clk/PWM.clock.
 
The PWM clock is always the master clock and not any external clock.
Thus the Clk setting can be any external CV used to clock this sequencer
(such as an LFO)
or the master clock if that is what is timing this sequencer.

The 16 toggles (above the rotary encoders) select between Yellow switch/off/clock patterns.
Up = Yellow switch pattern; Middle = off; bottom = clock pattern.

This means that if the switch is in the bottom position, the output will have a clock signal,
and if it is in the top position, it will have whatever the yellow toggle is displaying.
...........................................................................
 B3-B1
The B3 Gate sequencer is linked to the B1 CV sequencer.
 
Slight difference to c4-c1.
In the manual, it's called Gate expander 2 (page 18). 
This gate expander has 2 outputs (row 1 & 2) and runs in sync with the CV sequencer B1 .
 
The extreme left toggle with the yellow cap switches between Clock/skip/PWM.clock.
The extreme right toggle switches between rows 1 & rows 2
The 16 toggles (above the rotary encoders) select between Row 1/ off / row 2.
 Up = row 1 pattern; Middle = off; bottom = row 2 pattern.
 
 
 -----------------------------------------------------------------------
The A3 & A4 gate sequencers
 

The A3 gate sequencer has two rows of outputs -- row 1 (top), row 2 (bottom).
You select which row using each of the 16 switches above the pots.

The A3 gate sequencer exits from Gate output A.
Its outputs are PW/ Row 1/ Row 2
It is identical in function to the B3 gate sequencer

The A4 sequencer outputs via "Gate C4".
(I wonder if this was a mistake in the panel design ???
was it supposed to be A4??)
Its outputs are PW/Mute/Out/Trigger
It functions much like Gate sequencer C4



I'll add to this page over time.
please let me know if there are any mistakes.

Thermin - Silicon Chip

 Some pics of a build... the Silicon Chip Thermin.

https://www.siliconchip.com.au/Issue/2018/January/Make+your+own+Theremin+%E2%80%93+then+make+music%21

This kit has been stuck in a draw for over 10 years ??


This design is from 2009.

A friend recently asked for some help in building a thermin  using Bob Moog's design.

In the 1960s Moog had 4 designs :
The Vangard, (Vacuum tubes)
The Professional (Transistors)
The Melodia (Kit & built vesions)
The Troubador


The Melodia could be purchased as a kit.

I though before I embark on that project I'll build this and see what I can learn.






This is the inside of a Melodia.

This old instrument seems to be made up of transistors, oscillators, coils and wires which create electromagnetic fields around the instrument's two antennae. 
Thermin's rely on the human body's capacitance. When you move your body in and out of that electromagnetic field, you change the frequency of the oscillating circuit.
You are actually making a variable capacitor with your hand being one plate, and the antenna, the other.


What a thermin contains are basically two primary circuits:
1) a pitch circuit.
2) volume circuit.

These two circuits are connected to individual antennas.
Vol antenna is on the left. pitch on the right.
The antennas need to be separated by at least 20 inches & be about 3.5 feet from the ground.
According to the build guide these antenna coils are machine wound by a special method called
"progressive universal" and cannot be duplicated by hand wiring. 
 
It looks like though the original circuit is quite simple, its full of hard to find parts.
The most difficult to obtain being the inductors.
More about inductors are here:
 
Inductors are also called coils or chokes.
They are passive two terminal components.
Like capacitors, they store energy.
However, in this case, energy is stored as a magnetic field.
They are usually made up of a insulated (copper) wire, wound round a core (magnetic ... iron or ferrite).
 
 
The schematics indicate (L4) 10mH volume and (L1) 75mH pitch antenna inductors.
These are wound coils that I think were only available only from Moog.
I can't find any manufacturer’s part number.  
They might be custom-made for Moog ???? 
 

According to the vintage DIY manual:
"satisfactory substitues for the antenna coils can be made by connecting
three 25mhy ferrite chokes in series
and
for the volume: connect two 10mhy chokes in series. 

It seems like the rest of the inductors (the 4 within the metal case) can be hand wound.

The pitch circuit used two oscillators:
A variable oscillator and a fixed oscillator.
The variable oscillator produces a range of frequencies and is connected to the vertical antenna.
The fixed oscillator generates waves at a static frequency.
 
Signals from the fixed and variable oscillators were mixed together
and then amplified and output as sound.

The second circuit (the volume circuit) controls the volume of the pitch circuit.
To do this it uses an oscillator connected to an antenna.
Disrupting the electromagnetic field around this antenna changes the volume of the tones from
the pitch circuit.

---------------------------------------------------------------------

Some Links:

how to make your own inductors
 
 
 This webpage is really useful:
 
 
--------------------------------------------------------------------------
I'll start the silicon chip thermin build in another post
 


Saturday, 3 September 2022

Kate Bush and the Fairlight CMI

..

Very cool video lecture. Thanks Dori & Cliff.

Hounds of love:

Running Up that Hill

Cloudbusting
 Look for Kate Bush pulling out the book "Book of dreams" by Peter Reich from the pocket
of Donald Sutherland in the video. Kate is playing the role of Peter.
The hill on which the video is shot is Dragon Hill, This is immediately below the Uffington White Horse, a prehistoric hill carving (which  if you look carefully can be seen).
 
 
Under ice