Saturday, 20 December 2014

Friday, 19 December 2014

The Church of the Nativity - Bethlehem

In keeping with the Christmas theme, I thought I'd upload some pics of the Church of the Nativity in
Bethlehem. (PALESTINE)
The site of the Church of the Nativity is a World Heritage Site, and was the first to be listed under the name of the State of Palestine.

The site is also on UNESCO's List of World Heritage Sites in Dange

It's one of the world's oldest surviving churches and marks the spot most Christians believe to be that of Christ's birth. Jesus was most likely born in a cave (known as the Grotto)... or in a house attached to a cave that would have been used for stabling and storage - thus the manger.

 This is part of the cave under the church foundations.

 Underground chapels

In 327 AD, Constantine and his mother St. Helena commissioned a church to be built over the cave. This first basilica, dedicated on May 31, 339, had an octagonal floor plan.

The roof looks like it's rotting & threatening the whole building. There are holes in the timbers above allowing water to drip down upon the precious paintings and mosaics below.

The actual problem isn't a lack of restoration money. It seems to be jealousy over who is responsible for the Church's maintenance. Three Christian denominations (Greek  Orthodox, Armenian Orthodox and the Franciscan order of the Roman Catholic Church) are fighting for control and neither seem to be able to agree.
Portions of the floor mosaic still survive from this period. These are 1700 years old. How any of this has survived is beyond belief. It's a miracle that the church has survived at all.
It's seen invasions, fires & earthquakes. In 2002 armed Palestinians hid in the church from Israeli forces.

 These columns are a wonder. Each carved from a single piece of red limestone. They stand tall and have watched over the church's survival.

St. Jerome lived and worked in Bethlehem from 384 AD, and he was buried in a cave beneath the Church of the Nativity.

The Constantinian church was destroyed by fire during the Samaritan Revolts in the sixth century AD
So the Emperor Justinian rebuilt it in 530 AD. This much larger church is what we see today.
Justinian was a Byzantine (Eastern Roman Empire) Emperor. His capital, Constantinople is today's Istanbul. During his reign Constantine tried to revive Rome's greatness and recapture the lost Western half.

He never succeeded. The Eastern half became the Byzantine Empire. The west developed into what we now know as Western Europe.

The Persians spared it during their invasion in 614 AD because, according to legend, they
were impressed by a representation of the Magi — fellow Persians — that decorated the building.

The Crusaders took Jerusalem on 6 June 1009. Baldwin I and II were crowned there. Baldwin I was crowned the first King of Jerusalem on the 24th December 1100.

Much of the current external appearance is Crusader. Much restoration work was accomplished between 1165 & 1169.
The Crusaders were defeated by Saladin (Salah al-Din Yusuf ibn Ayyub) in 1187 at Hattin in Galilee.
This led to a Muslim occupation of Bethlehem. Most of the Christian community had to leave. They only returned in 1192..... The Muslim powers allowed this after payment of a stiff tax. Thus, the history of Bethlehem swayed this way and that over the coming centuries. Armies came and went. It always however remained a important place of pilgrimage.

Between the years 1219-1220, it was visited by none other than Francis of Assisi. He arrived in the port of Acre which was still in the hands of the Crusaders. He went to Egypt to the court of the Sultan Malek al-Kamil. It is reported that the Sultan was so struck by the personality of the saint that he granted him a safe-conduct for his journey to Palestine.

This church looks more like a fortress than a place of worship.

The four-foot-high "Door of Humility,"

This is the main entrance to The Church of the Nativity. It was once much larger & grander.

Over the centuries it's size has shrunk for defensive reasons. No longer can horses (& I guess armies)
be ridden into the church. Even a Emperor will have to dismount and stoop his head if he wishes to go inside.

There used to be a pointed arch over the doorway.

Light in the Grotto is supplied by 53 lamps, 19 of which belong to the Latins.

The entrance to the crypt & grotto below

  Star of Bethlehem and Altar

The Roman Catholics have control over this section of the church. 

Also called the Grotto of the manger, the silver star marks the spot where Christ is said to have been born. 

To illustrate the competition between the warring churches its recorded that of the 15 lamps that hang above the star, 6 are Greeks, 5 belong to the Armenians and 4 to the Latins.

Dove of Peace


Thursday, 18 December 2014

ARP 2500 - Sample & Hold (videos 1 and 2)

Experimenting with getting a clock out from the sequencer (to sync the sample & hold)
The sequencer's clock goes into the 2 sample ins.

Set the "clock in" toggle to the off setting


Video two. Using the S & H to modulate the filter

You can download some audio from this patch here:

Tuesday, 16 December 2014

ARP 2500 - SAMPLE & HOLD / RANDOM VOLTAGE (1036 module)

In electronics, a sample and hold circuit is a device that captures the voltage of a continuously varying signal. It holds onto its last sampled value until the input is sampled again
This saved voltage can then be used to control VCOs, filters, VCAs, etc.

The ARP 2500 sample + hold module is no different.

It's official name is the 1036 - S/H - Random Voltage.

A typical sample and hold circuit stores electric charge in a capacitor and contains at least one fast FET (field effect transistor) switch and at least one operational amplifier.

It looks like the 1036 uses this design.
The schematic & BOM can be found here: GuitarFool
The OpAmp seems to be a LM301
The switch - a 2n5172 ???

As the name implies it also has random triggers and more.
The 1036 is in fact a dual sample and hold.. Each S&H circuit is identical & independent.
The 1036 also contains a voltage controlled pulse generator & a white noise source.

 Each upper section of the S&H 1036 has 3 inputs and 2 outputs.

(1) External Signal input.(this is where the voltage to be sampled goes).
(2) Clock frequency modulation (VC for the pulse generator).
(3) Sample Command Input.(The pulse goes here).
(1) Clock out
(2) Out (Sample out).

The VC pulse generator can be used to re-trigger the S-H circuit there by "re-sampling the input voltage & creating a new output voltage".

When a pulse is applied to the "Sample Command Input" (SCI), the output CV is immediately (10ms) given the same value as the input CV. This Output CV will remain unchanged until a new pulse is applied to the SCI.

There are 3 ways to generate these Sample Command Pulses:
(1) Pushing the Red Sample Button.
(2) Applying an pulse from an external source (eg a keyboard trigger, sequencer or an oscillator) to the SCI
(3) Use the Internal Clock Pulse Generator.

The frequency of the clock pulse generators are determined by the two silver knobs & the slide switches.
The pic is pretty self explanatory.

The clock frequency can also be modulated by applying a voltage to the "Clock Frequency Mod" inputs.

Here is a pic of the upper inputs/outs:

The lower in/out section of this module is more flexible than the upper since we have some attenuation pots.

These CLOCK PULSE outputs can be used to provide COMMAND PULSES. for the SAMPLE inputs.
CLOCK PULSES are +10V. Their duration lasts as long as the sample period.

Between the two red sample buttons are 3 toggle switches.
The toggle on the left connects Clock (a) with Sample & hold (a).
The toggle on the right connects Clock (b) with Sample & Hold (b).
The middle toggle connects Clock (a) with sample & hold (b).
So Clock (a) can be used to control both S&H circuits, and Clock (b) is restricted to its namesake S&H.

It can be a bit confusing, but any voltage which you wish to sample must be applied to the Ext Sig input (Not the Sample input).

For each Dual S&H module there are two Ext Sig Inputs at the top & two at the bottom on the module.
The bottom ones are really cool as the signal has attenuation potentiometers .. The top inputs are un-attenuated.

In addition to sampling external signals the 1036 can produce random signals

The control for this are these two silver knobs called the Int Random Sig. (Internal Random Signal Generators).
Advancing these knobs will introduce noise into the inputs of the sample & hold circuit.
If we sample only the random signal then you will hear a series of stepped random voltages.
The fun begins when you start to sample external voltages.

You can mix the external signal (EXT SIG) with the internal random signal (INT RANDOM SIG) before they get to the sampler.

One last point to discuss is the Trig/Gate switch.

When a pulse enters the sample input two different results can be selected depending of whether the switch is in the Trig or Gate position.

So what's the difference between a trigger and a gate?
Trigger =   short duration
Gate =      longer duration 

In the trig position, the +ve edge of the pulse will trigger the sampler for about 10ms
In the GATE position the output of the sample and hold remains 'Open' for the whole time that the command pulse is positive.

The choice that you have between using a trigger or a gate in the ARP 2500 is absent in the later ARP 2600. The model 2600 uses the 4015 sub-module and works only with sharply rising waveforms or triggers.

Sydney Seige

This is a tribute to Katrina Dawson & Tori  Johnson.
Two young people whose lives were taken away too soon.

Everyone I know is devastated and we are all thinking of their families, friends.
This horrible act was meant to divide us. Instead it will make us stronger
#Illridewithyou #prayforsydney

Friday, 12 December 2014

NonLinearCircuits - panel 7 & 8 installation (Vox & Drum)

Finally getting these puppies installed. The NLC synth is close to finished.
(One panel to go).

These are pics of the VOX panel:

The Veena module is based on a circuit that simulates Indian Instruments.
It takes its name from the family of Indian plucked string instruments bearing the Veena title.
Their origin can be traced back to the ancient yazh, a stringed instrument, similar to the Grecian harp.
There are many manufacturers of Indian electronic instruments. Probably the largest is Radel

Veena build MANUAL includes schematic (27/2/13)

Initial installation tests. Fits perfectly. :-)

These are pics of the Drum Panel (8):

Andrew has based the Dr GoGo drum on the old Roland Dr 55

The dual drum module named 'Die Blechtrommeln' is based on some old Japanese circuits.
It takes it's name from the 1979 German film 'The Tin Drum.
(the added 'n' is the plural form)
For more info check out Andrew's Blog

The Envelope follower can also be used as a attack-release envelope Gen.
+ 2 LFOs (triangle / square)

The QUO = Quadrature Oscillator.
There is also a low pass filter with chaotic feedback in this section.

The 2 VCAs are also ring modulators. These are based off an EMS Synthi E circuit.