Wednesday, 12 July 2017

NLC Plague of Demons

Plague of Diamonds Eurorack module build notes.

Checkout electronotes EN #75.

It's a thru zero VCO that uses analogue switches (DG202) rather than FW rectifiers.
Should be easy to use; LEDs indicate when it crosses zero. 

My understanding of the through-zero concept is that with a regular VCO, if the frequency modulation reaches or goes below 0, you won't hear anything. With a thru zero VCO, you'll hear "negative" frequencies.  

"The negative-frequency version of a waveform is simply a time-reversed replica of the original waveform". (Ian Fritz. 2009)
Check out Dave Brown's scope shots on his site (
of the Ian Fritz "teezer" Thru-Zero VCO
They explain the concept so well.
The BOM requires:
a S1JL rectifier
Mouser No: 821-S1JL

and a JFET
Mouser No: 512-MMBFJ108

Both have a long backorder wait at mouser.
So possible replacements are:
mouser no: 771-PMBFJ108-T/R for the JFET
Mouser Part No: 583-FM4005-T for the recitfier.
The rectifier is polarized. The cathode end is marked with a band. 

This replacement is slightly too big for the PCB. so i had to solder it on its side.
On the PCB, I think Andrew has marked the cathode with a dot.

NLC words of wisdom

I like to get the ICs on first.

I'm using PCB version 2, so some mods are needed.
Had to cut one trace and add two resistors (10k & 2.2M).
Be careful not to short anything ... its a bit tricky

* NLC Blog
* Build notes
* Electro-music (Ian Fritz)
* mUFFwiggler

To be continued

Tuesday, 11 July 2017

NLC 32:1 - build notes

This is a Driscoll/Warren Burt inspired Eurorack module.

I am lucky to have the original Driscoll module on which this is based
so am keen to compare the two.

 The 32:1 can split 1 input into 32 outputs or vice versa.

This uses two CMOS analog multiplexers.
Mouser Part No:
A multiplexer is a device that can select from several different input signals
and transmit either one or more output signals
The DG506B is a 16-channel single-ended analog multiplexer designed to
connect one of sixteen inputs to a common output as
determined by a 4-bit binary address (A0, A1, A2, A3).

It also uses two CMOS up/down counters.
Mouser Part No:

 The CD4029 is a presettable up/down counter which counts in either binary or decade mode depending on the voltage level applied at binary/decade input.
When binary/decade is at logical ``1'', the counter counts in binary, otherwise it counts in decade. Similarly, the counter counts up when the up/down input is at logical ``1'' and vice versa.

The inputs consist of a clock (15), Carry In (5), Binary Decade (9), UpDown(10), Preset Enable(1)
and 4 individual jam signals.
The outputs : Q1,Q2,Q3,Q4 and a Carry Out (7).

* Build notes & BOM
* NLC Blog
* Youtube

Thursday, 6 July 2017

Serge Positive Slew - Paperface - restoration

Some pics of the Positive Slew.
This is from panel 2.1 (Warren Burt paperface).

 The red IC socket holds a LM3900 opamp which I swapped.
No improvement though. :-(
The module is powered by -12V (bottom blue), +6V (Green), +12V (Red), 0V (Blue top)

Connecting the lower pulse output to START or SUSTAIN should cause the Positive Slew to operate as a VCO or LFO..

The module uses two OpAmp ICs:
a  LM3900 & a MC 3401

The above pin out is for the MC 3401 operational amplifier.
The Motorolar MC3401, is out of production.
It seems to be responsible for providing both pulse outputs .
The lower pulse output exits pin 9.
The upper exits via pin 10
It seems that the Opamp is being used as a Schmitt trigger circuit with positive feedback.
The Schmitt trigger will convert any regular or irregular waveform into a pulse or square wave.
The LM 3900 is used extensively throughout the serge modules... in this circuit its used in a negative feedback config. 
It's interesting that both Quad op amps have identical pinouts.
I wonder if we can swap the MC3401 for LM3900s . My next question is why Serge chose
to use the MC3401s in the first place.
Another possible substitute for the MC3401 could be the CA3401 ???

This style of banana socket are I think impossible to remove without breaking them.
A post shared by jono (@dj_jondent) on

To be continued.

1. Ken Stones CGS - Positive Slew
2. DUSG - CGS 
4. Tim Stinchcombe

Serge Restoration Paperface 2.1

This is the upper panel from box 2

This contains:
  • Dual Positive Slew
  • Dual Negative Slew
  • 2 Smooth and Stepped Function Generators
  • 1 Dual VC Slew Generator
  • 1 Peak and Trough 




 The lower module is the negative slew


NLC PSU build 2

This is a smaller version of a Nonlinearcircuit PSU I built earlier.

I'm putting together this PSU for an old Serge modular but its actually for Eurorack.
The serge uses +12, -12, +6 and ground so I will have to add a 6V regulator to this later.

Some pics:

The PCB receives 12VAC from a plugpack/ wallwart
. The 1N4004 diodes split this into positive and negative waveforms.

The 4700uF capacitors then smooth out these waves
. The 7812 and 7912 regulators then convert the rectified & smoothed
signals to +12V DC and -12V DC and these are fed to the connectors to be distributed to your lovely modules.
I'm using 250v TDK film caps for the four small 100nf caps

 Poor Grandma.
Let's Eat Grandma is a British musical group formed in 2013 by childhood friends Rosa Walton and Jenny Hollingworth. 

I decided to use 1K resistors for the LEDs

 Some pics of the additional 6V regulator circuit.
 Using a LM7806
 330nf on the left. 100nf on the right.

Red +12V, Black 0V, White -12V, Green +6V

Wednesday, 5 July 2017

Hsinbyume Pagoda - Myanmar (Burma)

This beautiful all white structure on the banks of the Irrawaddy river just North of Mandalay.

 The pagoda that is also known as the Mya Theindan Pagoda.It is located in the Northern part of Mingun town near the massive Mingun Pagoda.

 The all white pagoda was built in 1816 by Prince Bagyidaw.

The structure was dedicated to his first wife, Princess Hsinbyume, which literally translates to White Elephant Princess, who died during child birth. During the large earthquake of 1838 the Hsinbyume Pagoda was severely damaged.