Saturday, 8 October 2022

Thermin- part 3 build - completion

This is part 3 of the Thermin build.
The earlier parts are  here:
Part 1
Part 2:
 
This is the build so far.
Resistors, caps, IC headers, trimmers are in.



There are two types of Diodes:
1n4004 x 4
1n4148 x 2
.

The 1n4004 form a bridge rectifier.
 
 The power supply is a 12V AC  job.
These rectify the AC to DC.
 
 It can also be powered with a DC battery.
But don't use a 12DC switchmode power supply
 
 
 
 
 
 
 
 
 
 
 
 
 
These are replacements for the inductors used in the original schematics.

IF oscillator Coil.
Its commonly used in radio receivers.
These coils can be bought to different specs.
Usually colour coded

In this project a black and 3 white are used.
..
The IF coil  is also known as an inter-frequency transformer.
The basic characteristic of every coil is inductance.
Their inductance can be adjusted by stretching or squeezing the coil turns.
 
The metal casing contains two coils. 
The first coil on the left is connected to a capacitor forming an oscillator circuit. 
The second coil transfers the signal to the next stage.

Install the voltage regulator.

Its a 7809 delivering 9V to the circuit.
final components... volume pot, power jack, switch, etc
 
 
 .... first tests
 

 

The antenna.Volume plate.
Its made from 1mm gauge aluminium.
 
                                                                                          Pitch antenna

connect speaker.


..
Tuning
The T1 reference coil doesn't need much adjustment.

 

NLC Mult - build pics

 It's a mult ... non buffered.
 

 
Just 2HP

















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Elk Elektroniks - meeting 08/10/22

 Some pics from yesterday's synth meeting.
Thanks Ed for hosting.
 

..


Thanks Robert.
 


One interesting bit I learnt was the art of starving a module (on purpose) of power.
Eg reducing the current on a +12v rail to push certain parts of the circuit and create new noise.
Flight of harmony -- famine 250 & 500

 
"What is Famine?
Famine is a voltage-controlled power starvation module, a teasing taste of electronic death – with the ever-present threat of the real thing. Your system will squeal, stutter, fuzz, and shriek, in new ways as you torture it while discovering the sublime joys of Schadenfreude".(FOH)
(Schadenfreude = pleasure derived by someone from another person's misfortune.)

 

The visuals were all done using a rasberry pi and some midi controllers.

Looks like a cool project for the future. Thanks Paul G.

https://andreijaycreativecoding.com/




A performance on the digitak - Elektron. Demo and discussion of the new firmware with song mode.







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A new term:
Stochastic Sequencer
Stochastic meaning “having a random probability distribution”
It makes melodies based on your input of how much you want of each note... So you can, for example, make a melody in E minor by cranking up the E, a bit of B, a dash of G and F#,etc.
Then set it to do its thing.
 
This is the Si Sig (Stochastic Inspiration Generator)
 
Other examples are:
Reaper’s Stochasticizer
Vermona Melodicer
Stochastic Sequencer module for VCV Rack
  
TEIA  also made a Stochastic Function Generator Eurorack Module.
I think its out of production but it  generaterated random values between two settings. 
Can loop like an LFO or fire on a gate in either AD or AHD modes. 
It had a Toggle switch  which selected 3 speed ranges.
 
 



 
The next meeting is scheduled for November in Wollongong.
Check the Elk Elektroniks facebook page for details and updates.
 

Friday, 7 October 2022

Herbs and stone Liquid foam

This is a quirky groove box.
Very acid sounding -- like a TB 303
 
Here’s a pdf of the official manual.
Mine was built from a kit ... just the PCB and panel were supplied.
All parts were easy to find.
 
The synth is a easy and cheap way to enter the world of Banana Synths.
If you have a Serge system, this is a perfect addition.
The important thing to remember is that any jack with a circle around it is an input.
All other jacks are outputs.

I'm powering mine from a old 6V adapter, so I like to keep any voltages that I'm inputting
from external synths in that range... 5V is safe.
 
The Liquid Foam is monophonic.
Its made up of 2 sequencers, a DAC, an analog VCO, one 2 pole 12dB/oct LP filter, one EG, 
a CMOS based overdrive and a wave mixer/shaper.
 
The sequencers
It has two square shaped sequencers ... left and right .
They are unusual in that you can't see any of the usual note info, etc that you would normally
see with a sequencer.
Both are linked to the master clock ( but they are slightly differently from each other).
The 8 jacks in these sequencers are outputs.
(It's ok to stack outputs)

 
 
The Left sequencer
The left one  rotates in a clock wise direction.
It's controlled by the main clock.

The right is influenced by the LFO & the clock.
It seems to bounce up and down

Note that both sequencers output gates  .... on/off 5V pulses.
They don't output any specific pitch info.
 
X & Y are modifiers for the left sequencer .
They change the rotational direction of this sequencer.
The X/Y jacks are only inputs.  

 
If we start to stack cables into these inputs you will see
the usual clockwise direction of this sequencer 
start to change





The right sequencer & LFO


The right sequencer is linked to the LFO (and clock)
It's a rectangle wave LFO.
 
You can change its width & rate 
So you can set how long the pulse width is.
 
By tweaking the LFO rate & width you can send the 
sequencer into a counter clockwise direction.
 
Use this sequencer to add randomness and stop 
your patterns going stale. I like to plug these outputs 
into the X/Y inputs for the right sequencer


 
 
So if these sequencers are only outputting 5V gates how does the synth produce CVs for pitch?
The answer lies with a DAC ... a digital to analog converter.
 
The DAC (and VCO Pitch)


A, B & C inputs are connected to a (3-bit ??)  DAC which converts any 5V gates into
control voltages for pitch. I think these CVs must pass through a quantiser before 
reaching the pitch input of the VCO.
There is a max of 7 different pitches which can be created.
The pitch you will finally hear depends on the gate combination.
The combination (from low to high pitch) are:
A, B, AB, C, AC, BC, ABC,
 
The simple combination  of gates converted into CVs with a basic DAC produces really 
interesting patterns which I don't think would be easy to replicate with a standard sequencer.
 
 
The Envelope Generator
 
I addition to the LFO, the liquid Foam has a single
envelope generator. 
The envelope is triggered every time a gate is received 
at inputs A, B or C. 
 
It's primary route is to the filter cut-off frequency
I like to use this as kind of an accent.
 
 
Note that the EG doesn't have an attack. Its decay only, but there is an offset.
The decay will control the length of the envelope.

The envelope has two inputs. 
The upper input will invert the envelope. (that influences the filter cutoff) 
The invert knob will then set how much that inverted signal will effect the filter.
This means that the same sequence can have different envelope slopes on different steps.

However, if you connect a gate onto the "eg->VCO", the EG will now influence the VCO pitch.
This will also bypass any gates received at inputs A,B or C. 
When combined with an inverted envelope, this can be used to produce glides between notes.


Wave mixer
 
There are two sets of wave mixers with two knobs
for the upper & lower mixers.
The mixer combines triangle / saw & rectangle
waves with variable pulsewidth. 

 
 
The top knob controls the shape of the waveform.
Extreme anti-clock (left)= triangle
Extreme right = saw
In between  = will combine both waves
 
The lower knob works really well if the upper knob is in the triangle stage (extreme left).
But it mixes whatever is in the top stage (tri/saw or their combination) with a rectangle wave 

Playing around with these two knobs give a really interesting transition between different waves.

 

Wednesday, 5 October 2022

The suppository of All Wisdom - NLC - Build notes - part 2 - completion

This is part 2 of my build notes for the Suppository of all Wisdom module.
It's supposed to be a phase shifter.



Part one of the build is here:

Links

It's a vactrol controller phaser by NLC ( Nonlinear circuits).
The module combines ideas from the Steiner Phaser with the Lovetone Doppelganger.
It uses lots of LEDs and LDRs (Light dependent resistors).

The PCB so far.
I like to solder the ICs first.
 

The two phaser sections are in series and Andrew decided to drop
the stepped capacitors and use a 10nF thru-out instead.

I understand, there are 8 stages to this phaser.
There are 2 outputs named:
1. Stage 8
2. Mix out (this is a combination of stage 4 & stage 8)

There are 2 (audio) inputs:
AC in
DC in

There are 2 CV inputs/pots
Phase 1 and CV1 control stages 1-2, 
Phase 2 and CV2 control stages 3-4.

I think the Colour Pots 1 & 2 are feedback pots.
One sends the signal from stage 4 back to stage 1 or into stage 5 (which totally 
overloads stage 5 as it is already getting the same signal from stage 4….oh dear). 
The other feedback pot sends the signal from stage 8 back to stage 1 or stage 4. 




You'll be building a single light-tight box.  with headers.... essentially make a big vactrol.
Made up of 4 LDRs surrounded by lots of LEDs.... everything effects everything else ...so results
might be a tad unpredictable.
 

Resistors & caps.
I'm using stepped caps
C1 = 4n7, C2 = 10n, C3 = 22n and C4 = 47n.


Schottky diodes

Headers to build the box



Andrew recommends :
"GL5506 or GL5516 or whatever"
I'm using GL5549 s only because I have a packet of them which I've hardly used .



LEDs:
Andrew recommends:
"red/yellow/green very bright ones"
I'm going multi coloured.

 Pretty !!!
Almost there

Pots
100k linear taper

ok ... you're done
 
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You can find more NLC builds here.
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