Wednesday, 18 September 2019

Synth Surfers - Bega Valley Synth Festival

Looking forward to the Bega Valley Synth Festival.
Just 1 month to go.

Workshops, demonstrations and displays in the day and OSCILLATIONS with live performances from local and interstate synth artists at night

There will be demonstrations/displays during the day and performances at night.
This is an inaugural event

The day is full of workshops to learn everything from DIY synth coding to Ableton Live to learning VCV Rack a free modular software synthesiser. There are displays of a variety of instruments and synthesiser formats all set up ready for you to try and play on.

10am - 12pm: Synthesis and sound design in Ableton Live
This workshop will give you a basic introduction into subtractive synthesis using the Ableton Live and the Simpler instrument.

12.30pm - 1.30pm & 1.30-pm - 2.30pm: Lunetta Synthesis
Join Adam Buckley as he gives you an introduction to the basics of creating your own synthesiser using the Lunetta Synth Cookbook.

3pm - 4pm & 4pm - 5pm: Intro to VCV Rack
VCV Rack is a free open-source virtual modular synthesiser:

10am - 5pm  - demo of the AE Modular from tangible waves.
See the latest modules from the newest modular format with demonstrations from tangible waves representative Carsten Eckelmann/The5thVoltScott Baker/Abre Ojos.

7.30 till late - OSCILLATIONS - Live electronia performances.
Local artists playing alongside artists from further afield. Featuring The 5th Volt . Myst Mach . Abre Ojos . DJ Jon Dent . Virus Installer . Vitals . DJ Hedge Zeppelin & more to be added!

When : Sat, October 19th.
Time: 10am till late.
Location: Murrah Hall 2989 Tathra - Bermagui Road

+ Murraha Hall
+ ACT Synthesizer Group
+ Facebook

Tuesday, 17 September 2019

211 power supply

Some pics of the Buchla Format 211 PSU

Perfect for a small system.
These are personal pics to help trouble shooting the build.
They are not official build notes.

The build however looks pretty straight forward except for one surface mount component (IC3).

Get those ICs on first.
There are 3 ICs
LM2575 IC1 1 926-LM2575SX-5.0NOPB
LM27313 IC2 1 926-LM27313XMF/NOPB
LM25575 IC3 1 926-LM25575MHX/NOPB

Some closeups:

IC 1: LM2575
 The LM 2575 is a switching, step down voltage regulator
The LM2575 and L3  inductor are used for the +5V supply.


IC2 (LM27313) and the inductor L2 are used for the +15V supply.


IC 3 

This IC is a voltage regulator. LM25575
It supplies -15V (along with the L4 inductor)


Quite tricky to solder by hand.



Noise, LC Filters, Inductors, etc

noise, Noise, and MORE NOISE.

Filtering noise is really important when building your synth.
Lots of ways to do this and the method may vary depending on the scale ... does the noise effect the whole synth (the PSU) or a small part of a circuit.
Decoupling capacitors, Ferrite beads, Inductors, LC Filters ??

I guess before you do this, you need to ask the questions;
  1. Are you better off filtering the noise, or preventing noise in the first place?
  2. Is there actually much noise to begin with?
  3. Is any LC filter you might install making more noise than it is removing?

On the macro level, a common method is to use something like a LC filter.  This often is found in the psu (the main power supply). An LC filter consists of inductors ( represented by the letter L) connected in series with the power flow and capacitors (represented by the letter C) from the filtered voltage to ground.

Ferrite Beads
A ferrite bead and capacitor is another form of LC Filter. It is often used to filter power for specific power pins on an IC.  They are frequently used on sensitive parts of a circuit like PLL’s & analog sections.

 LC filters are used to keep noise in one section of the circuit from getting to another section.

Decouplig Caps.
A decoupling capacitor is a capacitor used to decouple one part of an electrical network (circuit) from another. Noise caused by other circuit elements is shunted through the capacitor, reducing the effect it has on the rest of the circuit. (Wikipedia)

Also known as bypass capacitors.
They act as energy reservoirs ... you will often see them close to ICs ... they help to smooth out any voltage fluctuations.

You can also use decoupling caps on your main power distrobution board.
Here is an example for eurorack:
NLC power distro board

Below is a LM7805 voltage regulator.
Notice the two decoupling capacitors:
The capacitors are placed between the power line & ground.
The 0.33uF helps to smooth out any low-frequency changes in an input voltage. 
The 0.1uF helps to smooth out any of the high-frequency noise at the output.
Combining these two caps helps to deliver a smooth uninterrupted voltage to your circuits.

As mentioned earlier, decoupling are often used with ICs. Logic circuits tend to do lots of sudden switching ... between on & off with not much in between..So decoupling caps help to smooth  and stabilize the input voltage..... absorbing excess voltage if the voltage spikes suddenly, and providing more power to the IC should the voltage suddenly drop.   

The decoupling capacitors are connected between your power source, whether that’s 5V or 3.3V, and ground. (Generally it's recommend to use a 100nF ceramic capacitor and a larger 0.1-10uF electrolytic capacitor for each integrated circuit).

These 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 wire, wound round a core (magnetic ... iron or ferrite).

We measure inductance in units of Henry (H).
1Henry = 1 volt of EMF across the inductor with 1 Amp of current.
The larger the number, the higher the inductance.
The higher the inductance, the more energy we can store and provide.
It will also take longer for the magnetic field to build.

Ferrite Beads.
Also called Ferrite chokes, cores, rings, blocks, EMI filters.
These are passive components that suppress high frequency noise.
They are often wrapped around cables to  prevent the cable from acting like an antenna and receiving interference from other devices.

These are snap on ferrite beads. The upper pic shows one used at the end of a USB cable.

Ferrite beads convert Radio Frequency (RF) energy to heat. They are like a filter.
(Contrast this with inductors, which by design do not convert RF energy to heat, but rather offer a high impedance to RF.) 

 On the left is an inductor. To the right is a PCB ferrite bead.
You will probably have seen many of the PCB ferrite beads in DIY synth modules.

Saturday, 14 September 2019

ARP 2500 - modular jamming 070919

Some more jamming on the old arp.

Vitals on the keys

Just playing around with ideas for a future track.

Video is just from a mobile phone

Modular Jamming 070919 - buchla 100

My friend Mitch (Vitals) visited the other day.
Had some fun jamming with the old gear.

Nothing polished ... working with ideas... hopefully one day something from here will find its way onto an album

 Mainly Buchla 100 .. mixing vintage & new

The audio is just from a mobile phone (sorry)

Friday, 13 September 2019

1/n - NLC Build pics

Some build pics as I put together this module.
The 1/n by NonlinearCircuits is a eurorack format module.
Andrew says this circuit is straight out of the Lunetta playbook.

These pics aren't official ... just my personal notes to help with troubleshooting.

Wafer thin :-)

This is of course a reference to monty python.

 sOME  pre soldering pics

+ NLC blog
+ NLC Wiki
+ Official build notes

i LIKE to put the ICs in first.

To be continued ... waiting for some parts.

Thursday, 12 September 2019

LED Wiring

Some very basic info re LEDs
Light Emitting Diode orientation.
The earliest LEDs seem to have appeared around 1962
Before this there were incandescent lamps (you will see these used on early Buchla 100 modules... eg the 123 sequencer)

Anode - positive, long lead
Cathode - flat side, short lead

Note: If there is no flat side marked on the PCB use a multimeter to find the ground.
Usually, the ground is the round pad = .cathode (though I have seen the reverse being used).

In my experience, LEDs usually follow the same convention as used in electro caps.
Most aluminum caps come with the positive lead longer than the negative and when inserting them I aim the longer lead for the square hole.

So with LEDs, usually this holds:
The square pad represents POSITIVE
The round pad represents NEGATIVE

But, to be sure, use your multimeter to locate ground which connects with the cathode.

Multi colour LEDS

Bi-polar LEDs

These are two colour LEDs
Actually, there are two LEDs in the one case connected to the same two leads
Current flowing in one direction emits one color, and current flowing in the opposite direction emits the other color.

You will probably see these used a lot in synths.
Like regular LEDs, they have just 2 pins : Anode & Cathode
but they also allow two colours (red & green for example) .
Only one colour will appear at a time.... this is determined by the polarity of the connection.

This feature is very useful if you are trying to identify the polarity of a voltage 

I used this type of LED when building the NLC sloth.

The most common colours are red/traditional green, however, other colours include amber/green, red/green, red/blue, and blue/green.

Tri- colour LEDs


LED's that provide three or more colours can have two, three or four pins allowing for a wide range of mixed colours. Some have a common Cathode. With other types, the anode is common.
There some types with only 2 leads (anode + Cathode) ....  here, the colour is determined with a built in electronic controller.

Two LED Tri-colour
These have 3 pins but contain just 2 LEDs (red & green) in the one package.
When both the red and green LEDs are turned on, the LED appears to be yellow.

The common cathode is the centre leg, which is where the resistor should be fitted.
The outer leads are both anodes. .... allowing the LEDs to be lit separately
Green is the shorter leg.

These contain one green, one red and one blue LED in the single package.
They however have 4 Leads with a common cathode (usually).
This allows simultaneous use of all the LEDs. If you illuminate the different LEDs to different levels you can achieve almost any colour.

These are sometimes called multi-colour LEDs since more colours than just RGB can be achieved.


The LED Drive circuit

LEDs are current dependent and thus it is necessary to protect them from excessive current with a resistor. You attach the resistor in series (Rs).
To determine the required resistance use this formula:

Rs = (supply voltage - LED voltage)/LED current.

You can usually find the LED voltage from its data sheet.
Eurorack will have a supply voltage of 12V.
You just need to work out the current.

NLC nonlinearcircuits Sloth

Bahai Hanging Gardens of Haifa - Israel

These are  Terraces of the Bahá'í Faith, also known as the Hanging Gardens of Haifa.

You can see the garden terraces around the Shrine of the Báb on Mount Carmel in Haifa, Israel.

 The gardens rest in the neighborhoods of Wadi Nisnas and Hadar HaCarmel.


Personal notes & manuals

+ 222e
 + 225e
      *My notes re the 225e 
+ 250e
      * My notes on the 250e
       *  My notes on the 251e
+ 252e
      * Notes on the 252e
+ 261e
       * Notes on the 261e VCO
+ 266e
       * Notes on the 266e
 + 200e Firmware upgrade 

+ 1010 Bitbox - midi triggering

+ Xpander

Monday, 9 September 2019

Roland CR -78 CompuRhythm - Repair pics

Some repair pics of a Roland drum ..the  Cr 78

Just 4 screws need to be removed from the base if you want to open her up.

The drum has been in storage for many years ... in mint condition ... at least externally.

However, it looks like the battery has leaked.

Hopefully, the damage will be easily repaired.

tHIS  is the underside of the drum:

+ Synth Peter - replacing battery
+ Synth Peter - repairing a Cr 78