Sunday, 28 June 2015

VCS 3 - Putney

Messing around with the old Putney.
She is beautiful to behold and still sounds incredible after all these years.
Some pics of the patch:
I'm sampling during this video to see what I can come up with.
This is the unedited version.


Wednesday, 24 June 2015

555 Resonator Build Notes - NLC (NonLinearCircuits)

This is one of my favourite NLC circuits.
It's very versatile. It can be used as a filter, a VCO, a voltage controlled noise source and a voltage controlled drone module.

The module will oscillate without input (depending on the pot settings).
I like inputting a signal from a VCO which will trigger each 555 IC to create pulses.
These pulses can be manipulated with CV to create complex waveforms.

Andrew's manual for the 555 can be found here:
And his official build notes are here:

I have a version of this module in Serge/Banana format.

This build however is for a Eurorack Format module.
First, some pics of the virgin panel & PCB before we begin.

The module takes it's name from the 555 timer IC. This integrated circuit is used in a variety of timer, pulse generation, and oscillator applications. It's a very common IC and is cheap as chips.
The standard 555 package includes 25 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8) .

There are plenty of great videos on this versitile chip:

Andrew's module uses 5 of these 555s.  If I understand Andrew's schemos correctly,
each is part of an individual one shot circuit (also known as a Monostable Multivibrator).

Pin 1 is grounded.
Pin 2 - The trigger input.(connected to C5 - 1nf cap)
Pin 3 - Output.
Pin 4 - usually connected to + VCC to avoid accidental reset.
Pin 5 - grounded through a capacitor (c3 - 10nF?) to avoid noise problems. (This is the decoupling cap?).
Pin 6 - (threshold) is shorted to pin 7 - both are connected to ground via C6 (10nF cap).
Pin 7 - connected to the pin 6 & the discharge capacitor (not shown in the above schemo) - C6 
           C6's discharge time determines the pulse width.
Pin 8 - connected to the supply VCC.

The output of the 555-Monostable Multivibrator/oneshot remains low until a trigger pulse is applied to pin 2. 

It's probably a good idea to install the headers for these ICs along with the other 3 ICs and power connector first.

The other integrated circuits used in this build are two TL072s & one TL074.
The TL07x series are pretty common Op Amps that you will often find in synthesizers.
The TL 072 is a low noise JFET input Op Amp .....commonly used in filters & audio preamps.
The TL074 is a quad Op Amp.
Each of these 4 operational amplifiers incorporates well matched, high-voltage JFET and bipolar transistors. Each op amp has 1 input & 2 outputs (inverting & non-inverting). Voltage is on pins 4 & 11.

But before I install all these, I'll install the resistors, then caps & trannies

The easy ones first.
10uF electro caps (x7), 1nF (x10) & 10nF polyesters (x5).

Now it's time to install the 'cp' caps & decoupling caps.
 The cp caps & trannies form VC resistors that control the pulse width of the signal from each 555. Andrew has suggested starting with 10nF caps and then experimenting with different values.

Next the decoupling capacitors. As their name implies, they decouple or separate one part of a circuit from another. 555 ICs can be very noisy and these caps absorb some of the noise, reducing the effect one part has on another. There are 15 of these caps.

Andrew has suggested values between 47nF & 100nf. He says that the exact value won't make any difference. Use whatever fits and you have a lot of. "The main point is the 555s have plenty of decoupling, hence the 10uF as they virtually short +V to gnd as they do their thing".

Next, the transistors. These include ten BC 547 & ten BC557.
The BC 547 is a NPN transistor.
The BC 557 is a PNP. The cp capacitors and the transistors form VC resistors that control the pulse width of the signal from each 555.

Install the pots:

And the jacks.
Initial jack connections: Blue = Ground, Black = Out, Brown = In.
Test to see how it sounds as a filter by plugging in a sound source (eg: your Dual VCO).

Now connect the rest of the jacks.

Wow ... looks and sounds great !!!
     Useful Links:
1.  NLC filter panel
2. NLC notes (5 more)
Click here to return to the NLC Build Index:

Monday, 22 June 2015

Korg DDD-1 Drum Machine

The Korg DDD-1 hails back from 1986-87.
The good old days when sampling was a dirty 12-bits of zeros & ones.

This a a bargain for $100. Sure it's all beaten up but this makes it a perfect candidate for hacking into
it with my soldering iron. There are plenty on mods on the net.
CircuitBenders will modify yours.

Even without the mods there are 4 expansion slots for external ROM cards
and a RAM card too.

AngelFire produce custom pcb cards for the expansion slots.

The drum sounds include: kicks, snares, toms, rimshot, closed hi hats, open hi hats, ride, crash, claps, cowbell, tambourine and cabasa. The trigger pads are velocity sensitive and the tuning & decay of the sounds can be edited.

There are 6 individual outs plus sampled out.
Midi In/out
For more info on the history of Korg Drum Machines Click Here

Saturday, 20 June 2015

ARP 2500 - The Speed of Life

Some pics of this patch:
The 1027 Sequencer & 1050 mixer
It's patched to provide a 8 step sequence.

Just 3 modules being used here: two filters & a EG. (1047, 1006, 1046)

2 VCOs The 1004T & 1023

Friday, 19 June 2015

The White Desert - Egypt

The White Desert is located 45 km (28 mi) north of the town of Farafra. It has massive chalk rock formations ... the main reason for going there ... apart from the the great sunsets & the fun that is
camping in the desert.

An uplifting and unearthly place. Beautiful wind-carved rock formations shaped in the form of giant mushrooms ... we could be on another planet.

unearthly and beautiful wind-carved rock formations shaped in the form of giant mushrooms - See more at:
unearthly and beautiful wind-carved rock formations shaped in the form of giant mushrooms - See more at:
These deposits were formed during the Mesozoic era and are part of the ancient Tethys Ocean. They are calcium carbonate (a form of limestone). The Mesozoic Era covers a pretty broad expanse of time (262 - 66 million years ago). So this place was once under the ocean.

Great sunsets ... these pics don't do the place justiice.

We spent one night sleeping under the stars.When the camp fire went out the temp dropped and it was freezing. The water in those bottles is frozen.

A warning to all would be travelers.

Thursday, 18 June 2015

Moog-Polyevolver Jam

Sat 6th June.
Paul has new studio.
Checked out some toys.

What's not to love about the MiniMoog Voyager XL - it's got everything - ribbon controllers, touch pads, midi, CV, great filters, it's semi modular .... the list is endless.

Remix # 2
Moogerfoogers .... Mmmmmmm :-)

Dave Smith Poly Evolver & Korg Stage Piano

Video 2 - mainly samples of the Korg stage paino & DS polyevolver:

Tuesday, 16 June 2015

Serge TKB build notes - 10 - Wiring the Faceplate to PCB

***Click here for the Index of the TKB Build *** 

We are almost there.:-)

We need to make the final connections between the Faceplate and the PCB.
This is the guide:

What do these numbers & letters stand for ? (from left to right):
3 – A OUT
4 – B OUT
5 – C OUT
6 – D OUT
8 – KV
2 – ON/OFF Switch (Tab closest to panel edge)
The 4 pot boards also need to be wired to the PCB
 9 – A POTS
10 – B POTS
11 – C POTS
12 – D POTS

This is how you connected in the 1970s.
I've circled in red  connections 11 & 12 to C & D pots

I'm connecting the A,B,C,D pots from here on the modern TKB:

Almost home. 

Just need to connect # 17 ... the LED RETURN


***Click here for the Index of the TKB Build ***